阅读说明：本技术 丙烯酸酯聚合物微球聚集体及其制备方法 (Acrylate polymer microsphere aggregate and preparation method thereof ) 是由 陈忠 项炜 于 2019-10-10 设计创作，主要内容包括：本发明提供一种具有毛细管作用的丙烯酸酯聚合物微球,所述丙烯酸酯聚合物微球具有核壳结构,其核层的亲水性强于壳层的亲水性。本发明还提供制备本发明的丙烯酸酯聚合物微球的方法,通过调节核层与壳层的单体组成与比例,使之具有不同的亲水性能；通过调节pH值,使核层线型聚合物舒展开,并与壳层交联聚合物形成互穿网络结构；添加交联剂与核层线型聚合物反应使之交联形成稳定的聚合物互穿网络结构；经过干燥,微球内部的水分流失留下的微孔通道由于交联网络的存在得到支撑而稳定。本发明的丙烯酸酯聚合物微球聚集体可用作敷料。(The invention provides an acrylate polymer microsphere with capillary action, which has a core-shell structure, wherein the hydrophilicity of a core layer is stronger than that of a shell layer. The invention also provides a method for preparing the acrylate polymer microsphere, which has different hydrophilic properties by adjusting the monomer composition and the proportion of the core layer and the shell layer; by adjusting the pH value, the core-layer linear polymer is spread and forms an interpenetrating network structure with the shell-layer cross-linked polymer; adding a cross-linking agent to react with the core layer linear polymer to form a stable polymer interpenetrating network structure through cross-linking; upon drying, the microporous channels left by the water loss from the interior of the microspheres are stabilized by the presence of the crosslinked network. The acrylate polymer microsphere aggregate of the invention can be used as a dressing.)

1. The acrylate polymer microsphere is characterized by having a core-shell structure, wherein a polymer contained in a core layer has stronger hydrophilicity than a polymer contained in a shell layer, and the polymer contained in the core layer and the polymer contained in the shell layer of the acrylate polymer microsphere have cross-linking structures respectively; preferably, the polymer contained in the core layer of the acrylate polymer microsphere and the polymer contained in the shell layer are intertwined to form an interpenetrating network structure; preferably, the mass ratio of the polymer contained in the core layer to the polymer contained in the shell layer of the acrylic polymer microsphere is in the range of 1.5:1 to 1:1.5, preferably in the range of 1.2:1 to 1:1.2, and more preferably in the range of 1.1:1 to 1: 1.1; optionally, the acrylate polymer microspheres are adsorbed with an auxiliary agent.

2. The acrylate polymer microspheres of claim 1,

the core layer of the acrylate polymer microsphere contains a polymer obtained by copolymerizing a first crosslinkable monomer and one or more of methacrylic acid, acrylic acid, methacrylate monomers and acrylate monomers; preferably, the core layer of the acrylate polymer microsphere contains a polymer obtained by copolymerizing a first cross-linkable monomer, one or two monomers selected from methacrylic acid and acrylic acid and one or any more monomers selected from methacrylate monomers and acrylate monomers; preferably, the first crosslinkable monomer comprises 0.5% -5%, preferably 0.5% -3% of the total weight of the polymers contained in the core layer of acrylate polymer microspheres; preferably, the polymer contained in the core layer of the acrylate polymer microspheres is crosslinked via a crosslinking agent; preferably, the first crosslinkable monomer is diacetone acrylamide; preferably, the crosslinking agent is adipic dihydrazide; and/or

The shell layer of the acrylate polymer microsphere contains a polymer obtained by copolymerizing a second cross-linkable monomer and one or more of methacrylic acid, acrylic acid, methacrylate monomers and acrylate monomers; preferably, the shell layer of the acrylate polymer microsphere contains a polymer obtained by copolymerizing a second crosslinkable monomer and one or more of methacrylate monomers and acrylate monomers; preferably, the second cross-linkable monomer accounts for 0.5 to 5 percent of the total weight of the polymers contained in the shell layer of the acrylate polymer microsphere, and preferably accounts for 1 to 5 percent; preferably, the second crosslinkable monomer is ethylene glycol dimethacrylate;

preferably, the total content of methacrylic acid and acrylic acid in the polymer contained in the core layer of the acrylate polymer microsphere is higher than the total content of methacrylic acid and acrylic acid in the polymer contained in the shell layer.

3. The acrylate polymer microsphere of claim 2, wherein the core layer of the acrylate polymer microsphere comprises a polymer obtained by copolymerizing diacetone acrylamide, one or two monomers selected from the group consisting of methacrylic acid and acrylic acid, and one or more monomers selected from the group consisting of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, methyl methacrylate and methyl acrylate;

preferably, the core layer of the acrylate polymer microsphere contains a polymer obtained by copolymerizing diacetone acrylamide, methacrylic acid, hydroxyethyl methacrylate and hydroxypropyl methacrylate;

preferably, the total content of the methacrylic acid and the acrylic acid accounts for 2-15%, preferably 4-10% of the total weight of the polymers contained in the core layer of the acrylate polymer microsphere.

4. The acrylate polymer microsphere of claim 2, wherein the shell layer of the acrylate polymer microsphere comprises a polymer obtained by copolymerizing ethylene glycol dimethacrylate, one or two monomers selected from methyl methacrylate and methyl acrylate, and one or more monomers selected from methacrylate monomers other than methyl methacrylate and acrylate monomers other than methyl acrylate;

preferably, the shell layer of the acrylate polymer microsphere contains a polymer obtained by copolymerizing ethylene glycol dimethacrylate, methyl methacrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate;

preferably, the total content of the methyl methacrylate and the methyl acrylate accounts for 4-30%, preferably 8-20% of the total weight of the polymers contained in the core layer of the acrylate polymer microsphere.

5. An aqueous dispersion or aggregate of acrylate polymer microspheres containing the acrylate polymer microspheres of any one of claims 1-4; preferably, the aggregate of the acrylate polymer microspheres is obtained by drying an aqueous dispersion of acrylate polymer microspheres; preferably, the drying is freeze drying.

6. A method of making acrylate polymer microspheres, the method comprising:

(A) preparing an acrylate polymer microsphere core layer through first-step emulsion polymerization, wherein a polymer contained in the acrylate polymer microsphere core layer prepared through the first-step emulsion polymerization is a linear polymer and contains a crosslinkable group;

preferably, the monomers used in the first emulsion polymerization step include a first crosslinkable monomer and one or more monomers selected from the group consisting of methacrylic acid, acrylic acid, methacrylate monomers and acrylate monomers, preferably include a first crosslinkable monomer, one or two monomers selected from the group consisting of methacrylic acid and acrylic acid, and one or more monomers selected from the group consisting of methacrylate monomers and acrylate monomers, more preferably include a first crosslinkable monomer, one or two monomers selected from the group consisting of methacrylic acid and acrylic acid, and one or more monomers selected from the group consisting of hydroxyethyl methacrylate and hydroxypropyl methacrylate, one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, methyl methacrylate and methyl acrylate, more preferably including a first crosslinkable monomer, methacrylic acid, hydroxyethyl methacrylate and hydroxypropyl methacrylate; preferably, the first crosslinkable monomer is diacetone acrylamide; preferably, the total amount of methacrylic acid and acrylic acid used is from 2% to 15%, preferably from 4% to 10%, of the total weight of the monomers used in the first emulsion polymerization;

(B) preparing an acrylate polymer microsphere shell layer on the surface of the acrylate polymer microsphere core layer prepared by the first-step emulsion polymerization through the second-step emulsion polymerization to obtain a core-shell emulsion, wherein a polymer contained in the acrylate polymer microsphere shell layer has a cross-linked structure;

preferably, the monomers used in the second emulsion polymerization step include a second crosslinkable monomer and one or any more monomers selected from the group consisting of methacrylic acid, acrylic acid, methacrylate monomers and acrylate monomers, preferably include a second crosslinkable monomer and one or any more monomers selected from the group consisting of methacrylate monomers and acrylate monomers, more preferably include a second crosslinkable monomer, one or two monomers selected from the group consisting of methyl methacrylate and methyl acrylate and one or any more monomers selected from the group consisting of methacrylate monomers other than methyl methacrylate and acrylate monomers other than methyl acrylate, more preferably include a second crosslinkable monomer, methyl methacrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate; preferably, the second crosslinkable monomer is ethylene glycol dimethacrylate; preferably, the total content of methyl methacrylate and methyl acrylate is from 4% to 30%, preferably from 8% to 20%, of the total weight of the monomers used in the emulsion polymerization of the second stage; and

(C) adjusting the pH value of the core-shell emulsion prepared by the emulsion polymerization in the second step to be more than 7, preferably between 7 and 9, and then adding a cross-linking agent for reaction to obtain the acrylate polymer microspheres; preferably, the crosslinking agent is adipic dihydrazide;

preferably, the total amount of methacrylic acid and acrylic acid used in the first emulsion polymerization step is higher than the total amount of methacrylic acid and acrylic acid used in the second emulsion polymerization step.

7. The method of claim 5, wherein the method further comprises: adding an auxiliary agent to the core-shell emulsion or the aqueous dispersion of acrylate polymeric microspheres after step (B), before step (C), or after step (C), such that the auxiliary agent is adsorbed by the acrylate polymeric microspheres.

8. The method of claim 5, wherein the method has one or more of the following features:

(1) the reaction temperature of the first step of emulsion polymerization is 50-90 ℃, preferably 65-75 ℃;

(2) the first cross-linkable monomer is used in an amount of 0.5 to 5%, preferably 0.5 to 3% by weight based on the total weight of the monomers used in the first emulsion polymerization step;

(3) the first step of emulsion polymerization uses sodium dodecyl sulfate as an emulsifier and potassium persulfate as an initiator;

(4) the reaction temperature of the second step of emulsion polymerization is 50-90 ℃, preferably 65-75 ℃;

(5) the amount of the second crosslinkable monomer is 0.5 to 5 percent, preferably 1 to 5 percent, of the total weight of the monomers used in the second emulsion polymerization step;

(6) the second step of emulsion polymerization uses potassium persulfate as an initiator; and

(7) the mass ratio of the monomers used in the first emulsion polymerization step to the monomers used in the second emulsion polymerization step is in the range of 1.5:1 to 1:1.5, preferably in the range of 1.2:1 to 1:1.2, and more preferably in the range of 1.1:1 to 1: 1.1.

9. Acrylate polymer microspheres, aqueous dispersions or aggregates thereof, obtainable by a process according to any one of claims 6 to 8; preferably, the aggregate of the acrylate polymer microspheres is obtained by drying an aqueous dispersion of acrylate microspheres; preferably, the drying is freeze drying.

10. A dressing comprising the acrylate polymer microsphere aggregate of claim 5 or 9.

Technical Field

The invention belongs to the field of medical materials, and particularly relates to an acrylate polymer microsphere aggregate powder dressing with a capillary effect.

Background

Medical dressings are medical materials used to cover sores, wounds, or other lesions. With the intensive research on the pathophysiology of the wound healing process, people understand the wound healing process more and more deeply, thereby leading to the continuous improvement and development of medical wound dressings.

Natural gauze is the earliest and most widely used type of dressing. But it has too high permeability, and is easy to dehydrate the wound surface; the wound surface is adhered, and the secondary mechanical injury can be caused during replacement; the microorganisms in the external environment can easily pass through the biological agent, and the chance of cross infection is higher; the dosage is large, the replacement is frequent and time-consuming, and the patients suffer from pain.

Synthetic fiber dressings have the same advantages as gauze, such as economy, good absorption properties and the like, and some products are self-adhesive, so that the use is convenient. However, these products also have the same disadvantages as gauze, such as high permeability, no barrier to particulate contaminants in the external environment, etc.

The polymeric film dressing is a relatively advanced dressing and has the characteristics that gases such as oxygen, water vapor and the like can be freely and thoroughly passed, and granular foreign matters such as dust, microorganisms and the like in the environment cannot pass through. However, it has the disadvantages of poor capability of absorbing seepage, relatively high cost, large chance of skin impregnation around the wound surface and the like, so the dressing is mainly applied to the wound surface which is not exuded after operation or used as an auxiliary dressing of other dressings.

The foamed polymer dressing is a dressing formed by foaming a high polymer material (PU), a layer of polymeric semipermeable membrane is usually covered on the surface of the dressing, and some dressings have self-adhesion. But the wound surface with low exudation may affect the self-debridement process due to the strong absorption performance; the cost is relatively high; the wound surface is not convenient to observe due to the opacity.

The main component of hydrocolloid dressing is a hydrocolloid with very strong hydrophilic ability-carboxymethylcellulose sodium (CMC), which is combined with hypoallergenic medical viscose, elastomer, plasticizer and the like to form the main body of dressing. The surface of the hydrocolloid dressing is a layer of semi-permeable polymeric film structure. The dressing can absorb exudate after contacting with wound exudate, and form a gel to prevent the dressing from adhering to the wound; meanwhile, the semi-permeable membrane structure on the surface can allow oxygen and water vapor to exchange, but has barrier property to external granular foreign matters such as dust and bacteria. But it has not very strong absorption capacity, so for high exudation wound surface, other auxiliary dressing is often needed to enhance the absorption performance; the product cost is high; individual patients may have disadvantages such as allergy to the ingredients.

Alginate dressings are one of the most advanced medical dressings at present. The main component of the alginate dressing is alginate, which is natural polysaccharide carbohydrate extracted from seaweed and is a natural cellulose. Alginate medical dressing is a functional wound dressing with high absorption performance and consists of alginate. The medical film can form soft gel after contacting wound exudate, provide an ideal moist environment for wound healing, promote wound healing and relieve wound pain.

All of the above-mentioned natural or synthetic dressings have some inevitable disadvantages. Therefore, there remains a need in the art for a medical dressing that has an excellent combination of properties.

Disclosure of Invention

Aiming at the defects of the existing dressing, the invention designs a synthetic path by adopting the principles of molecular design and molecular engineering, so that the final product has stronger absorption performance, can form soft gel, provides an ideal moist environment for wound healing, promotes wound healing, relieves wound pain, is not adhered to a wound surface, is permeable to water and air, and can well block granular pollutants in the external environment.

Specifically, the invention provides an acrylate polymer microsphere which has a core-shell structure, and the polymer contained in the core layer has stronger hydrophilicity than the polymer contained in the shell layer.

In one or more embodiments, the polymer contained in the core layer of the acrylate polymer microspheres is intertwined with the polymer contained in the shell layer to form an interpenetrating network structure.

In one or more embodiments, the polymer contained in the core layer and the polymer contained in the shell layer of the acrylate polymer microsphere have a cross-linked structure.

In one or more embodiments, the mass ratio of the polymer contained in the core layer to the polymer contained in the shell layer of the acrylic polymer microsphere is in the range of 1.5:1 to 1:1.5, preferably in the range of 1.2:1 to 1:1.2, and more preferably in the range of 1.1:1 to 1: 1.1.

In one or more embodiments, the acrylate polymer microspheres are optionally adsorbed with an adjuvant.

In one or more embodiments, the core layer of the acrylate polymer microspheres contains a polymer obtained by copolymerizing a first crosslinkable monomer and one or any more monomers selected from the group consisting of methacrylic acid, acrylic acid, methacrylate monomers, and acrylate monomers.

In one or more embodiments, the first crosslinkable monomer is diacetone acrylamide.

In one or more embodiments, the methacrylate-based monomer is selected from the group consisting of hydroxyethyl methacrylate, hydroxypropyl methacrylate, and methyl methacrylate.

In one or more embodiments, the acrylate monomer is selected from the group consisting of hydroxyethyl acrylate, hydroxypropyl acrylate, and methyl acrylate.

In one or more embodiments, the core layer of the acrylate polymeric microspheres comprises a polymer obtained by copolymerizing a first crosslinkable monomer, one or two monomers selected from methacrylic acid and acrylic acid, and one or any more monomers selected from methacrylate monomers and acrylate monomers.

In one or more embodiments, the first crosslinkable monomer comprises from 0.5% to 5%, preferably from 0.5% to 3%, of the total weight of the polymers comprising the acrylate polymeric microsphere core layer.

In one or more embodiments, the polymer contained in the core layer of the acrylate polymeric microspheres is crosslinked via a crosslinking agent.

In one or more embodiments, the crosslinking agent is adipic dihydrazide.

In one or more embodiments, the shell layer of the acrylate polymer microsphere contains a polymer obtained by copolymerizing a second crosslinkable monomer and one or more of methacrylic acid, acrylic acid, methacrylate monomers and acrylate monomers.

In one or more embodiments, the second crosslinkable monomer is ethylene glycol dimethacrylate.

In one or more embodiments, the shell layer of the acrylate polymer microsphere contains a polymer obtained by copolymerizing a second crosslinkable monomer and one or any more monomers selected from methacrylate monomers and acrylate monomers.

In one or more embodiments, the second crosslinkable monomer comprises from 0.5% to 5%, preferably from 1% to 5%, of the total weight of the polymers contained in the shell layer of the acrylate polymeric microspheres.

In one or more embodiments, the core layer of the acrylate polymer microspheres contains a polymer having a higher total methacrylic acid and acrylic acid content than the polymer contained in the shell layer.

In one or more embodiments, the polymer contained in the core layer of the acrylate polymeric microspheres contains methacrylic acid and/or acrylic acid, and the polymer contained in the shell layer of the acrylate polymeric microspheres does not contain methacrylic acid and acrylic acid.

In one or more embodiments, the core layer of the acrylate polymer microspheres comprises a polymer derived from the copolymerization of a first crosslinkable monomer, one or both monomers selected from methacrylic acid and acrylic acid, and one or any more monomers selected from hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, methyl methacrylate, and methyl acrylate.

In one or more embodiments, the core layer of the acrylate polymeric microspheres comprises a polymer derived from the copolymerization of a first crosslinkable monomer, one or both monomers selected from the group consisting of methacrylic acid and acrylic acid, and one or any more monomers selected from the group consisting of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate.

In one or more embodiments, the core layer of the acrylate polymeric microspheres comprises a polymer derived from the copolymerization of a first crosslinkable monomer, methacrylic acid, and one or two monomers selected from the group consisting of hydroxyethyl methacrylate and hydroxypropyl methacrylate.

In one or more embodiments, the core layer of the acrylate polymeric microspheres comprises a polymer derived from the copolymerization of a first crosslinkable monomer, methacrylic acid, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

In one or more embodiments, the total amount of methacrylic acid and acrylic acid present is from 2% to 15%, preferably from 4% to 10% by weight of the total weight of the polymers present in the acrylate polymeric microsphere core layer.

In one or more embodiments, the shell layer of the acrylate polymer microsphere contains a polymer obtained by copolymerizing a second crosslinkable monomer, one or two monomers selected from methyl methacrylate and methyl acrylate, and one or any more monomers selected from methacrylate monomers other than methyl methacrylate and acrylate monomers other than methyl acrylate.

In one or more embodiments, the shell layer of the acrylate polymer microsphere comprises a polymer obtained by copolymerizing a second crosslinkable monomer, one or two monomers selected from the group consisting of methyl methacrylate and methyl acrylate, and one or any more monomers selected from the group consisting of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, methacrylic acid, and acrylic acid.

In one or more embodiments, the shell layer of the acrylate polymer microsphere comprises a polymer obtained by copolymerizing a second crosslinkable monomer, one or two selected from the group consisting of methyl methacrylate and methyl acrylate, and one or any more selected from the group consisting of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate.

In one or more embodiments, the shell layer of the acrylate polymer microsphere comprises a polymer obtained by copolymerizing a second crosslinkable monomer, methyl methacrylate and one or two monomers selected from hydroxyethyl methacrylate and hydroxypropyl methacrylate.

In one or more embodiments, the shell layer of the acrylate polymer microspheres contains a polymer resulting from the copolymerization of a second crosslinkable monomer, methyl methacrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

In one or more embodiments, the total amount of methyl methacrylate and methyl acrylate present is from 4% to 30%, preferably from 8% to 20%, of the total weight of the polymers present in the core layer of acrylate polymer microspheres.

The present invention also provides an aggregate or aqueous dispersion of acrylate polymer microspheres comprising the acrylate polymer microspheres described in any one of the embodiments of the present invention.

In one or more embodiments, the aggregates of acrylate polymer microspheres are obtained from an aqueous dispersion of acrylate microspheres by drying.

In one or more embodiments, the drying is freeze-drying.

The invention also provides a method for preparing the acrylate polymer microspheres, which is characterized by comprising the following steps:

(A) preparing an acrylate polymer microsphere core layer through first-step emulsion polymerization to obtain a core emulsion, wherein a polymer contained in the acrylate polymer microsphere core layer prepared through the first-step emulsion polymerization is a linear polymer and contains a crosslinkable group;

preferably, the monomers used in the first emulsion polymerization step include a first crosslinkable monomer and one or more monomers selected from the group consisting of methacrylic acid, acrylic acid, methacrylate monomers and acrylate monomers, preferably include a first crosslinkable monomer, one or two monomers selected from the group consisting of methacrylic acid and acrylic acid, and one or more monomers selected from the group consisting of methacrylate monomers and acrylate monomers, more preferably include a first crosslinkable monomer, one or two monomers selected from the group consisting of methacrylic acid and acrylic acid, and one or more monomers selected from the group consisting of hydroxyethyl methacrylate and hydroxypropyl methacrylate, one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, methyl methacrylate and methyl acrylate, more preferably including a first crosslinkable monomer, methacrylic acid, hydroxyethyl methacrylate and hydroxypropyl methacrylate; preferably, the first crosslinkable monomer is diacetone acrylamide; preferably, the total amount of methacrylic acid and acrylic acid used is from 2% to 15%, preferably from 4% to 10%, of the total weight of the monomers used in the first emulsion polymerization;

(B) preparing an acrylate polymer microsphere shell layer on the surface of the acrylate polymer microsphere core layer prepared by the first-step emulsion polymerization through the second-step emulsion polymerization to obtain a core-shell emulsion, wherein a polymer contained in the acrylate polymer microsphere shell layer has a cross-linked structure;

preferably, the monomers used in the second emulsion polymerization step include a second crosslinkable monomer and one or any more monomers selected from the group consisting of methacrylic acid, acrylic acid, methacrylate monomers and acrylate monomers, preferably include a second crosslinkable monomer and one or any more monomers selected from the group consisting of methacrylate monomers and acrylate monomers, more preferably include a second crosslinkable monomer, one or two monomers selected from the group consisting of methyl methacrylate and methyl acrylate and one or any more monomers selected from the group consisting of methacrylate monomers other than methyl methacrylate and acrylate monomers other than methyl acrylate, more preferably include a second crosslinkable monomer, methyl methacrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate; preferably, the second crosslinkable monomer is ethylene glycol dimethacrylate; preferably, the total content of methyl methacrylate and methyl acrylate is from 4% to 30%, preferably from 8% to 20%, of the total weight of the monomers used in the emulsion polymerization of the second stage; and

(C) adjusting the pH value of the core-shell emulsion prepared by the emulsion polymerization in the second step to be more than 7, preferably between 7 and 9, and then adding a cross-linking agent for reaction to obtain the acrylate polymer microspheres; preferably, the crosslinking agent is adipic dihydrazide;

preferably, the total amount of methacrylic acid and acrylic acid used in the first emulsion polymerization step is higher than the total amount of methacrylic acid and acrylic acid used in the second emulsion polymerization step.

In one or more embodiments, the method further comprises: adding an auxiliary agent to the core-shell emulsion or the aqueous dispersion of acrylate polymeric microspheres after step (B), before step (C), or after step (C), such that the auxiliary agent is adsorbed by the acrylate polymeric microspheres.

In one or more embodiments, the method has one or more of the following features:

(1) the reaction temperature of the first step of emulsion polymerization is 50-90 ℃, preferably 65-75 ℃;

(2) the first cross-linkable monomer is used in an amount of 0.5 to 5%, preferably 0.5 to 3% by weight based on the total weight of the monomers used in the first emulsion polymerization step;

(3) the first step of emulsion polymerization uses sodium dodecyl sulfate as an emulsifier and potassium persulfate as an initiator;

(4) the reaction temperature of the second step of emulsion polymerization is 50-90 ℃, preferably 65-75 ℃;

(5) the amount of the second crosslinkable monomer is 0.5 to 5 percent, preferably 1 to 5 percent, of the total weight of the monomers used in the second emulsion polymerization step;

(6) the second step of emulsion polymerization uses potassium persulfate as an initiator; and

(7) the mass ratio of the monomers used in the first emulsion polymerization step to the monomers used in the second emulsion polymerization step is in the range of 1.5:1 to 1:1.5, preferably in the range of 1.2:1 to 1:1.2, and more preferably in the range of 1.1:1 to 1: 1.1.

In one or more embodiments, the acrylate polymer microspheres produced by the method are the acrylate polymer microspheres described in any one of the embodiments of the present invention.

The invention also provides acrylate polymer microspheres, aqueous dispersions or aggregates thereof prepared by the method described in any of the embodiments of the invention.

In one or more embodiments, the aggregates of acrylate polymer microspheres are obtained from an aqueous dispersion of acrylate polymer microspheres by drying; preferably, the drying is freeze drying.

The invention also provides a dressing comprising an acrylate polymer microsphere aggregate as described in any of the embodiments of the invention.

Drawings

Fig. 1 to 6 are electron micrographs of the acrylate polymer microsphere aggregate prepared in example 1, wherein the magnification of fig. 1 and 2 is × 50, the magnification of the method of fig. 3 and 4 is × 100, and the magnification of fig. 5 and 6 is × 500.

FIG. 7 is a graph showing the weight loss ratio of water in the acrylate polymer microsphere aggregate prepared in example 1 after absorbing water to form a film, as a function of time.

FIG. 8 is an infrared spectrum of an acrylate polymer microsphere aggregate prepared in example 1.

FIG. 9 is a heat flow curve of the acrylate polymer microsphere aggregate prepared in example 1.

FIG. 10 is a plot of the particle size distribution of the acrylate polymer microsphere aggregates prepared in example 1.

Detailed Description

To make the features and effects of the present invention comprehensible to those skilled in the art, general description and definitions are made below with reference to terms and expressions mentioned in the specification and claims. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

The theory or mechanism described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, i.e., the present disclosure may be practiced without limitation to any particular theory or mechanism.

All features defined herein as numerical ranges or percentage ranges, such as values, amounts, levels and concentrations, are for brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to cover and specifically disclose all possible subranges and individual numerical values (including integers and fractions) within the range.

Herein, unless otherwise specified, the ratio refers to a mass ratio, and the percentage refers to a mass percentage.

In this context, for the sake of brevity, not all possible combinations of features in the various embodiments or examples are described. Therefore, the respective features in the respective embodiments or examples may be arbitrarily combined as long as there is no contradiction between the combinations of the features, and all the possible combinations should be considered as the scope of the present specification.

According to the invention, a new technical means is introduced in the preparation process of the acrylate polymer microspheres, so that microporous channels are formed in the synthesized polymer microspheres, a new capillary channel is formed when the polymer microspheres are gathered in the drying process, and the interaction of the two channels enables the acrylate polymer powder to be quickly fused together to form a polymer film with good water and air permeability when encountering a substance containing moisture, thereby promoting the wet healing of wounds.

The invention adopts a core-shell emulsion polymerization method to prepare polymer microspheres with microphase separation, firstly synthesizes a polymer core containing more hydrophilic monomers, then adopts a continuous dropwise adding process to prepare a polymer shell containing more lipophilic monomers, and controls the crosslinking density and the ionization degree of the core and the shell, so that the polymer of the core and the shell generates microphase migration in the post-treatment process to form an interpenetrating network structure. Due to the existence of the hydrophilic monomer, a large amount of bound water is contained in the particles, and in the later drying process, the space occupied by the original water forms a micropore channel due to the support of the interpenetrating network crosslinking structure. During the drying process, the fusion between the particles can form a certain capillary channel, and the interaction of the particles and the capillary channel enables the acrylate polymer microsphere aggregate to be quickly fused together to form a polymer film with microscopic channels when contacting with a substance containing moisture. The core-shell structure of the polymer microsphere enables the microsphere aggregate to have a microphase separation structure. Therefore, the acrylate polymer microsphere aggregate has an interpenetrating network cross-linking structure and a microphase separation structure, so that a polymer film formed after meeting water has high strength and high elasticity.

Herein, the microsphere refers to a microspherical particle having a particle size in the nanometer and micrometer scale range; the polymer microspheres refer to microspheres with a polymer as a main component. The acrylate polymer microsphere is a polymer microsphere with a polymer forming monomer mainly selected from one or more of acrylic acid, acrylate monomers, methacrylic acid and methacrylate monomers. Herein, the acrylate polymer refers to a polymer in which monomers are mainly (e.g., 90% or more, preferably 95% or more) one or more monomers selected from acrylic acid, acrylate monomers, methacrylic acid, and methacrylate monomers.

Herein, the acrylate monomer may be various acrylate monomers known in the art, preferably one or more selected from the group consisting of hydroxyethyl acrylate, hydroxypropyl acrylate and methyl acrylate; the methacrylate-based monomer may be various methacrylate-based monomers known in the art, and is preferably one or more selected from the group consisting of hydroxyethyl methacrylate, hydroxypropyl methacrylate and methyl methacrylate.

Herein, when referring to the monomer containing or including one or both of acrylic acid and methacrylic acid, it is preferable to contain or include methacrylic acid and optionally acrylic acid because methacrylic acid has better polymerization stability in the present invention, and when acrylic acid is used alone, the polymerization process may be unstable to cause reaction failure in some cases.

Herein, when referring to the one or more monomers comprising the acrylate-based monomer and the methacrylate-based monomer, it is preferable to comprise or include the one or more monomers comprising the methacrylate-based monomer and optionally the acrylate-based monomer, because the polymer obtained by polymerizing the acrylate-based monomer has a low glass transition temperature, and in some cases, is too soft after being plasticized by absorbing water, and the α hydrogen of the acrylate-based monomer is easily attacked by radicals during the polymerization to cause the degree of crosslinking of the final polymer to be inconsistent with the intended degree.

Herein, the aqueous dispersion of the acrylate polymer microspheres refers to a substance in which the acrylate polymer microspheres are dispersed in water, and may be, for example, an emulsion.

Herein, the acrylate polymer microsphere aggregate refers to a small amount of microparticles formed by aggregating acrylate polymer microspheres, and is in a powder shape, so the acrylate polymer microsphere aggregate is also called acrylate polymer powder, acrylate polymer microsphere powder and acrylate polymer microsphere aggregate powder, and can be obtained by drying aqueous dispersion of acrylate polymer microspheres.

Herein, the core-shell structure refers to a structure in which one material is coated with another material having different physical or chemical properties by chemical bonds or other forces. The core layer (core) material and the shell layer material of the core-shell structure may be different in chemical composition or the same in chemical composition, but different in physical structure (such as density, pore size, microphase structure, etc.). The core layer material and the shell layer material of the core-shell structure can partially mutually permeate, namely, a transition layer can exist between the core layer and the shell layer of the core-shell structure. Therefore, in the case of the polymer microsphere, if there are two inner and outer layer structures having different physical or chemical properties as a whole, even if a part of polymers between the two layer structures are intertwined to form an interpenetrating network structure, the polymer microsphere is considered to have a core-shell structure.

Herein, the polymer (core layer polymer) contained in the core layer of the acrylate polymer microsphere is a polymer obtained by polymerizing a monomer used in the preparation of the core layer of the microsphere, and the polymer (shell layer polymer) contained in the shell layer of the acrylate polymer microsphere is a polymer obtained by polymerizing a monomer used in the preparation of the shell layer of the microsphere. Herein, even if the core layer polymer undergoes microphase migration during the subsequent preparation process and intertwines with the shell layer polymer to form an interpenetrating network structure, the polymer polymerized from the monomers used in preparing the core layer of the microsphere and the polymer polymerized from the monomers used in preparing the shell layer of the microsphere in the interpenetrating network structure are still considered as the core layer polymer and the shell layer polymer, respectively.

Herein, the polymer contained in the core layer (or shell layer) of the acrylate polymer microsphere contains a certain monomer (e.g., hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, methacrylic acid, acrylic acid, methyl acrylate, methyl methacrylate, ethylene glycol dimethacrylate, diacetone acrylamide, etc.) means that the polymer contained in the core layer (or shell layer) is polymerized from a monomer composition including the monomer.

The acrylate polymer microsphere has a core-shell structure, and both a core layer and a shell layer of the acrylate polymer microsphere contain acrylate polymers or consist of the acrylate polymers.

In certain embodiments, the mass ratio of the polymer contained in the core layer to the polymer contained in the shell layer of the acrylic polymer microsphere of the present invention is in the range of 1.5:1 to 1:1.5, preferably in the range of 1.2:1 to 1:1.2, and more preferably in the range of 1.1:1 to 1: 1.1.

In a preferred embodiment, the core layer and/or the shell layer of the polyacrylate polymeric microspheres of the present invention has a crosslinked structure, i.e. the core layer and/or the shell layer of the polyacrylate polymeric microspheres of the present invention contains or consists of a crosslinked acrylate polymer.

In certain embodiments, the core layer and/or the shell layer of the acrylate polymer microspheres of the present invention comprise a polymer obtained by polymerizing a monomer selected from one or more of methacrylic acid, acrylic acid, methacrylate-based monomers (e.g., hydroxyethyl methacrylate, hydroxypropyl methacrylate, and methyl methacrylate) and acrylate-based monomers (e.g., hydroxyethyl acrylate, hydroxypropyl acrylate, and methyl acrylate) and a crosslinkable monomer (hereinafter referred to as an acrylate polymer comprising a crosslinkable monomer). In the present invention, the crosslinkable monomer means a monomer having two or more functional groups available for polymerization or crosslinking, and may be, for example, Ethylene Glycol Dimethacrylate (EGDMA), diacetone acrylamide (DAAM), or the like. The amount of crosslinkable monomer may be an amount conventionally used in the art for crosslinking acrylate polymers, and is generally 0.5% to 5% by weight based on the total weight of the acrylate polymer.

In certain embodiments, the core layer of the polyacrylate polymeric microspheres of the present invention comprises a first crosslinkable monomer. Herein, the first crosslinkable monomer contained in the core layer is preferably a monomer having one carbon-carbon double bond available for polymerization and also having one or more functional groups (e.g., ketocarbonyl group) other than the carbon-carbon double bond available for crosslinking, and may be, for example, diacetone acrylamide or the like. In certain embodiments, the core layer of the acrylate polymer microspheres of the present invention comprises a polymer resulting from the copolymerization of a first crosslinkable monomer (e.g., diacetone acrylamide) and one or any number of monomers selected from the group consisting of methacrylic acid, acrylic acid, acrylate monomers, and methacrylate monomers. In certain embodiments, the core layer polymer is crosslinked via a crosslinking agent. The crosslinking agent suitable for the core layer polymer is not particularly limited as long as it matches the first crosslinkable monomer contained in the core layer, i.e., the crosslinking agent of the core layer polymer contains two or more functional groups (e.g., hydrazide groups) capable of reacting with the functional groups available for crosslinking other than the carbon-carbon double bond contained in the first crosslinkable monomer contained in the core layer, and for example, in the embodiment where the first crosslinkable monomer contained in the core layer is diacetone acrylamide, the crosslinking agent is preferably adipic acid dihydrazide (adipimide, ADH). The amount of crosslinking agent used can be routinely determined based on the amount of the corresponding first crosslinkable monomer, for example, adipic dihydrazide is used in an amount generally half the diacetone acrylamide content.

In certain embodiments, the core layer of the polyacrylate polymeric microspheres of the present invention comprises a polymer that is a polymer resulting from crosslinking of a linear acrylate polymer comprising a first crosslinkable monomer via a crosslinking agent; the first cross-linkable monomer is preferably diacetone acrylamide and the cross-linking agent is preferably adipic acid dihydrazide (adipic dihydrazide, ADH). In certain embodiments, the first crosslinkable monomer (e.g., diacetone acrylamide) comprises from 0.5% to 5%, preferably from 0.5% to 3%, of the total weight of the polymers comprising the core layer of acrylate polymer microspheres. In certain embodiments, the crosslinking agent (e.g., adipic dihydrazide) comprises from 0.25% to 2.5%, preferably from 0.25% to 1.5%, of the total weight of the polymers contained in the core layer of the acrylate polymer microspheres.

In certain embodiments, the shell layer of the polyacrylate polymeric microspheres of the present invention comprises a second crosslinkable monomer. Herein, the second crosslinkable monomer contained in the shell layer is preferably an acrylate or methacrylate monomer having two or more carbon-carbon double bonds available for polymerization, and may be, for example, ethylene glycol dimethacrylate, etc. In certain embodiments, the shell layer of the acrylate polymer microspheres of the present invention comprises a crosslinked polymer obtained by copolymerizing a second crosslinkable monomer (e.g., ethylene glycol dimethacrylate) and one or any more monomers selected from the group consisting of methacrylic acid, acrylic acid, acrylate monomers and methacrylate monomers. In certain embodiments, the second crosslinkable monomer (e.g., ethylene glycol dimethacrylate) comprises from 0.5% to 5%, preferably from 1% to 5%, of the total weight of the polymers contained in the shell layer of the acrylate polymer microspheres.

In some embodiments, the shell layer of the polyacrylate polymer microsphere of the present invention contains a second crosslinkable monomer (e.g., ethylene glycol dimethacrylate) having two or more carbon-carbon double bonds available for polymerization, and the second crosslinkable monomer is copolymerized with other monomers to form a polymer having a crosslinked structure without adding a crosslinking agent.

The hydrophilicity of the core layer of the acrylate polymer microsphere is stronger than that of the shell layer.

Herein, the hydrophilic monomer refers to a monomer having a hydrophilic group (e.g., carboxyl group, hydroxyl group, etc.), such as hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, methacrylic acid, acrylic acid, and the like. In general, hydrophilic monomers (e.g., methacrylic acid and acrylic acid) in which the hydrophilic group is a carboxyl group are more hydrophilic than hydrophilic monomers (e.g., hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate and hydroxypropyl acrylate) in which the hydrophilic group is a hydroxyl group, because the hydrophilicity and water absorption are greatly enhanced when the carboxyl group is neutralized by hydroxyl group to form carboxylate.

The method for realizing that the hydrophilicity of the core layer of the acrylate polymer microsphere is stronger than that of the shell layer is not particularly limited, for example, the core layer polymer may contain more hydrophilic monomers with equivalent hydrophilicity than that of the shell layer polymer, or the core layer polymer may contain hydrophilic monomers with stronger hydrophilicity, and the shell layer polymer may contain hydrophilic monomers with weaker hydrophilicity. In certain embodiments, the present invention makes the core layer of the acrylate polymer microsphere more hydrophilic than the shell layer by making the total content of methacrylic acid and acrylic acid in the polymer contained in the core layer of the acrylate polymer microsphere higher than the total content of methacrylic acid and acrylic acid in the polymer contained in the shell layer. In certain embodiments, the acrylate polymeric microsphere core layer contains 2% to 15%, preferably 4% to 10%, methacrylic acid and/or acrylic acid (preferably methacrylic acid) based on the total weight of the polymers it contains. In certain embodiments, the acrylate polymer microsphere shell is free of methacrylic acid and acrylic acid.

In certain embodiments, the core layer of the acrylate polymer microspheres comprises a polymer derived from the copolymerization of a first crosslinkable monomer (e.g., diacetone acrylamide), one or both selected from methacrylic acid and acrylic acid (preferably methacrylic acid), and one or any more selected from methacrylate monomers and acrylate monomers (preferably methacrylate monomers).

In certain embodiments, the core layer of the acrylate polymer microspheres comprises a polymer resulting from the copolymerization of a first crosslinkable monomer (e.g., diacetone acrylamide), one or both selected from methacrylic acid and acrylic acid (preferably methacrylic acid), and one or any more selected from the group consisting of other methacrylate monomers other than methyl methacrylate and methyl acrylate and acrylate monomers (e.g., hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate and hydroxypropyl acrylate, preferably hydroxyethyl methacrylate and hydroxypropyl methacrylate).

In certain embodiments, the core layer of the acrylate polymer microspheres comprises a polymer derived from the copolymerization of diacetone acrylamide, methacrylic acid, hydroxyethyl methacrylate, and hydroxypropyl methacrylate; preferably, the polymer contained in the core layer of the acrylate polymeric microspheres is crosslinked via adipic dihydrazide.

In embodiments where the microsphere core layer comprises methacrylic acid and/or acrylic acid, the acrylate polymeric microsphere core layer preferably comprises from 2% to 15%, preferably from 4% to 10%, methacrylic acid and/or acrylic acid (preferably methacrylic acid) by weight of the total weight of the polymers it comprises.

In embodiments where the microsphere core layer comprises a plurality of methacrylate monomers and/or acrylate monomers, the ratio of the methacrylate monomers and/or acrylate monomers is not particularly limited, for example, when the microsphere core layer comprises hydroxyethyl methacrylate and hydroxypropyl methacrylate, the mass ratio of hydroxyethyl methacrylate to hydroxypropyl methacrylate may be 10:1 to 1:10, such as 6:4, 8:2, 9:1, and the like.

In certain embodiments, the shell layer of the acrylate polymer microspheres comprises a polymer obtained by copolymerizing a second crosslinkable monomer (e.g., ethylene glycol dimethacrylate) and one or more monomers selected from the group consisting of methacrylate monomers and acrylate monomers (preferably methacrylate monomers).

In certain embodiments, the shell layer of the acrylate polymer microspheres comprises a polymer resulting from the copolymerization of a second crosslinkable monomer (e.g., ethylene glycol dimethacrylate), one or both of methyl methacrylate and methyl acrylate (preferably methyl methacrylate), and one or any more of methacrylic acid, acrylic acid, methacrylate monomers other than methyl methacrylate and methyl acrylate, and acrylate monomers (e.g., hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate, preferably hydroxyethyl methacrylate and hydroxypropyl methacrylate).

In certain embodiments, the shell layer of the acrylate polymer microspheres comprises a polymer obtained by copolymerizing a second crosslinkable monomer (e.g., ethylene glycol dimethacrylate), one or both selected from methyl methacrylate and methyl acrylate (preferably methyl methacrylate), and one or any more selected from methacrylate monomers other than methyl methacrylate and methyl acrylate and acrylate monomers (e.g., hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate and hydroxypropyl acrylate, preferably hydroxyethyl methacrylate and hydroxypropyl methacrylate).

In certain embodiments, the shell of the acrylate polymer microspheres comprises a polymer derived from the copolymerization of ethylene glycol dimethacrylate, methyl methacrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

In the embodiment where the shell layer of the microsphere contains a plurality of monomers selected from acrylic acid, methacrylic acid, methacrylate monomers and acrylate monomers, the ratio of the monomers selected from acrylic acid, methacrylic acid, methacrylate monomers and acrylate monomers in the shell layer is not particularly limited, as long as the total content of methacrylic acid and acrylic acid in the polymer contained in the shell layer is generally lower than the total content of methacrylic acid and acrylic acid in the polymer contained in the shell layer (for example, the polymer in the shell layer may not contain methacrylic acid and acrylic acid).

In embodiments where the shell layer of the microsphere comprises methyl methacrylate and/or methyl acrylate, the acrylate polymeric microsphere core layer preferably comprises 4% to 30%, preferably 8% to 20%, by weight of the total weight of the polymers it comprises, of methyl methacrylate and/or methyl acrylate (preferably methyl methacrylate); in such embodiments, the ratio of the methacrylate-based monomer and the acrylate-based monomer other than methyl methacrylate and methyl acrylate is not particularly limited, for example, when the shell layer of the microsphere contains hydroxyethyl methacrylate and hydroxypropyl methacrylate, the mass ratio of hydroxyethyl methacrylate to hydroxypropyl methacrylate may be 10:1 to 1:10, such as 5:4, 4:5, 3:6, etc.

In certain embodiments, the core layer polymer and the shell layer polymer of the acrylate polymer microspheres of the present invention are intertwined to form an interpenetrating network structure.

The acrylate polymer microspheres of the invention contain microporous channels.

The acrylate polymer microspheres of the present invention may be adsorbed with adjuvants, including, but not limited to, sodium deoxycholate, growth factors, and the like.

The invention provides a method for preparing acrylate polymer microspheres, which comprises the following steps:

(A) preparing an acrylate polymer microsphere core layer through emulsion polymerization in the first step to obtain a core emulsion;

(B) taking the acrylate polymer microsphere core layer prepared by the emulsion polymerization in the first step as a core, and preparing an acrylate polymer microsphere shell layer by the emulsion polymerization in the second step to obtain a core-shell emulsion; and

(C) adjusting the pH value of the core-shell emulsion prepared by the emulsion polymerization in the second step to be more than 7, preferably 7-9, more preferably 7.5-9, and then adding a cross-linking agent for reaction to obtain the acrylate polymer microspheres.

In the present invention, the monomers used in the first emulsion polymerization step may be monomers contained in the acrylate polymer microsphere core layer polymer described in any embodiment herein, and the monomers used in the second emulsion polymerization step may be monomers contained in the acrylate polymer microsphere shell layer polymer described in any embodiment herein, and the amount and ratio of the monomers may be as described in any embodiment herein.

In certain embodiments, the polymer contained in the core layer of the acrylate polymer microsphere prepared in step (a) is a linear polymer and contains crosslinkable groups.

In certain embodiments, the acrylate polymer microsphere shell prepared in step (B) has a crosslinked structure.

The first and second emulsion polymerizations of the present invention may be carried out using emulsion polymerization conditions conventional in the art. In certain embodiments, the reaction system of the first emulsion polymerization comprises a solvent (water), an emulsifier (e.g., sodium lauryl sulfate), a monomer, and an initiator (e.g., potassium persulfate), the reaction temperature can be 50 ℃ to 90 ℃ (preferably 65 ℃ to 75 ℃), the reaction can be carried out in a nitrogen atmosphere, and generally, after the monomer and the emulsifier are uniformly mixed in the solvent, the pre-dissolved initiator is added for the reaction, and the reaction time can be 3 to 12 hours (e.g., 6 hours). In certain embodiments, the reaction system of the second emulsion polymerization comprises the core emulsion obtained in the first emulsion polymerization, a monomer and an initiator (e.g., potassium persulfate), the reaction temperature may be from 50 ℃ to 90 ℃ (preferably from 65 ℃ to 75 ℃), the reaction may be carried out under a nitrogen atmosphere, the previously dissolved initiator may generally be added to the core emulsion, the monomer may be added dropwise slowly (e.g., at a rate of 2.5 g/h), and the reaction time may be from 1 to 4h (e.g., 2 h).

In step (C), the pH of the core-shell emulsion may be adjusted by means conventional in the art, for example, an alkaline substance, such as sodium hydroxide, may be added to the core-shell emulsion.

The core layer and the shell layer of the acrylate polymer microsphere have different hydrophilic performance differences, particularly when the pH value of the core-shell emulsion is adjusted to be more than 7 by using an alkaline substance, carboxyl contained in the core layer polymer is neutralized into carboxylate, molecular chains of the carboxylate are spread and can penetrate through the polymer layer of the shell layer, and a large amount of bound water can be contained in the polymer microsphere while an interpenetrating network structure is formed, so that a foundation for forming capillary micropores is provided for dried polymer powder.

The conditions for the crosslinking reaction in step (C) may be conventional crosslinking reaction conditions. In certain embodiments, the crosslinking agent used in step (C) is adipic dihydrazide, and the crosslinking reaction time may be 24 hours. The amount of cross-linking agent may be as described in any embodiment herein.

The core layer and the shell layer of the microsphere treated by the alkaline substance form an interpenetrating network structure, at the moment, a core layer polymer does not form a cross-linked network through chemical bonding, a cross-linking agent is required to be introduced to form chemical bonding, and the interpenetrating network structure through chemical bonding is obtained, so that a capillary micropore channel formed in the drying process is stabilized.

In certain embodiments, the method of making acrylate polymer microspheres of the present disclosure further comprises: and adding an auxiliary agent into the core-shell emulsion or the water dispersion of the acrylate polymer microspheres, so that the auxiliary agent is adsorbed by the acrylate polymer microspheres. The timing of addition of the auxiliary is not particularly limited, and may be, for example, after step (B), before step (C) or after step (C).

The present invention also includes aqueous dispersions of the acrylate polymer microspheres of the present invention.

The invention also provides an aggregate of the acrylate polymer microsphere of the invention, namely acrylate polymer microsphere powder. The acrylate polymer microsphere aggregate of the present invention may be obtained by drying an aqueous dispersion of acrylate polymer microspheres as described in any of the embodiments of the present invention.

The acrylate polymer microsphere aggregate contains micropore channels and capillary channels. The specific gravity of the acrylate microsphere aggregate of the present invention is usually 0.05g/cm³-0.06g/cm³。

In a preferred embodiment, the manner of drying is freeze-drying; the conditions for freeze-drying may be those conventional in the art, and may be, for example, the following conditions:

the vacuum degree is lower than 10 Pa;

the freezing procedure is as follows: 3 hours at-50 ℃; -40 ℃, 2 hours; 1 hour at-30 ℃; -20 ℃ for 1 hour; -10 ℃, 1 hour; 3 hours at 0 ℃; 1 hour at 10 ℃; 20 ℃ for 2 hours.

Before drying, some auxiliary agent can be added into the acrylate polymer microsphere aqueous dispersion, so that the auxiliary agent can be adsorbed by the polymer microspheres, and after drying, the auxiliary agent can be uniformly dispersed in the acrylate polymer powder.

The acrylate polymer microsphere with a core-shell structure is prepared by an emulsion polymerization method, the core of the polymer microsphere contains a linear polymer with potential crosslinking capacity, the linear polymer contains crosslinkable groups, and the shell of the polymer microsphere contains a spatial reticular crosslinked polymer and has a crosslinking structure; the core layer and the shell layer have different hydrophilic properties by adjusting the monomer composition and proportion of the core layer and the shell layer; adjusting the pH value of the core-shell emulsion by alkaline substances to spread the linear polymer of the core layer and form an interpenetrating network structure with the shell layer crosslinked polymer; crosslinking the core layer linear polymer by adding a crosslinking agent to react with the core layer linear polymer, and forming a stable polymer interpenetrating network structure of the core layer and the shell layer, thereby obtaining the capacity of forming a capillary micropore channel in the drying process; by drying, the microporous channels left by the water loss inside the polymer microspheres are stabilized by the presence of the cross-linked network, so that the acrylate polymer microsphere aggregate powder is obtained and can be used as a dressing.

The invention therefore also provides the use of the acrylate polymer microspheres of the invention, an aqueous dispersion thereof or aggregates thereof in the manufacture of a dressing. The invention also includes dressings, particularly medical dressings, comprising the acrylate polymeric microsphere aggregates of the invention.

The dressing of the present invention may be the acrylate polymer microsphere aggregate of the present invention itself, optionally further comprising various additives, adjuvants, pharmaceutical ingredients and active ingredients known in the art to be suitable for use in dressings, including, for example, but not limited to, antibacterial agents, hemostatic agents, anti-inflammatory agents, pH adjusting agents, nutritional agents, and the like. When the dressing of the invention is used, the dressing can be evenly shaken on skin or wound, a small amount of normal saline is sprayed on the dressing, and the dressing can form a high-water-absorption film with high elasticity and high strength after contacting moisture.

The dressing containing the acrylate polymer microsphere aggregate has the following advantages: after contacting with moisture, the film forming speed is high (generally, the film can be formed within five minutes), the formed film has good air permeability, transparency, water absorbability and adhesiveness and enough strength and elasticity, the wound healing condition can be observed conveniently, wound exudate can be absorbed, the film is tightly and firmly attached to a wound in the initial use stage, the film is not easy to damage under the action of external force, the tissue fluid exudation is reduced along with the prolonging of time or the healing of the wound, the high-water-absorption film is gradually dried and separated from the skin or the healed wound gradually, the skin or the wound cannot be adhered, the wound cannot be damaged when the dressing is removed, the film is easy to remove, and light pain is brought to a patient.

The present invention will be described in detail with reference to examples. The embodiments in the present description are only for illustrating the present invention, and do not limit the scope of the present invention. The scope of the present invention is defined only by the appended claims, and any omissions, substitutions, and changes in the form of the embodiments disclosed herein that may be made by those skilled in the art are intended to be included within the scope of the present invention.

The following examples use instrumentation conventional in the art. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out under conventional conditions or conditions recommended by the manufacturers. In the following examples, various starting materials were used, and unless otherwise specified, conventional commercially available products were used.

Example 1

Preparing an acrylate polymer microsphere aggregate by the following steps:

(1) the preparation process of the core comprises the following steps: 1.0g of emulsifier Sodium Dodecyl Sulfate (SDS) and 380g of deionized water are weighed into a 500mL four-neck flask, a stirrer, a nitrogen guide pipe, a thermometer and a condenser are installed, the water bath temperature is maintained at 73 ℃, nitrogen is continuously introduced, stirring is started, a weighed monomer mixture containing 12g of hydroxyethyl methacrylate (HEMA), 8g of hydroxypropyl methacrylate (HPMA), 1g of methacrylic acid (MAA) and 0.4g of diacetone acrylamide (DAAM) is added when the emulsifier is completely dissolved and the internal temperature reaches 70 +/-1 ℃, a dissolved potassium persulfate (KPS) solution containing 0.1g of KPS and 20g of deionized water is added after the temperature is stabilized, and the timing is started. After about 5min, the reactants are blue, the monomers begin to polymerize to form polymer particles, and after about 6h, the nuclear preparation reaction is completed to prepare the nuclear emulsion.

(2) The preparation process of the shell comprises the following steps: respectively weighing 210g of nuclear emulsion and 180g of deionized water into a 500mL four-neck flask, then installing a stirrer, a nitrogen guide pipe, a thermometer and a condenser pipe, keeping the water bath temperature at 73 ℃, continuously introducing nitrogen and starting stirring, adding a pre-dissolved KPS solution containing 0.1g of KPS and 20g of deionized water when the internal temperature reaches 70 +/-1 ℃, simultaneously beginning to dropwise add an acrylate mixed monomer containing 5g of HEMA, 4g of HPMA, 1g of Methyl Methacrylate (MMA) and 0.2g of Ethylene Glycol Dimethacrylate (EGDMA) at the speed of 2.5g/h, and continuously reacting for 2h after the monomer is dropwise added, thereby preparing the acrylate core-shell emulsion.

(3) The preparation process of the microporous structure comprises the following steps: and (3) adding sodium hydroxide into the acrylate core-shell emulsion prepared in the step (2) to enable the pH value to reach 7.5, then adding 0.1g of Adipic Dihydrazide (ADH), reacting for 24 hours to obtain an aqueous dispersion of the acrylate polymer microsphere with the core cross-linked, and freeze-drying to obtain the acrylate polymer microsphere aggregate.

The polymer particles prepared by adopting the core-shell emulsion polymerization means have the advantages that the core contains a large amount of hydrophilic monomers, the EGDMA in the shell realizes crosslinking, when sodium hydroxide is adopted to neutralize the polymer emulsion, carboxyl in the core is converted into sodium carboxylate, the hydrophilicity is greatly improved, as the difference between the hydrophilicity of the core and the hydrophilicity of the shell is large, the core material and the shell material are intertwined to form an interpenetrating network structure, ADH with equivalent amount to DAAM is added into the system after neutralization is finished, the two react to form a stable interpenetrating network structure, and as the existence of the hydrophilic materials such as the sodium carboxylate, the inside of the polymer particles contains a large amount of moisture. During the subsequent drying process, the micropore channels left by the water loss are retained due to the support of the crosslinking structure, so that the acrylate polymer microsphere aggregate containing a large number of micropore structures is finally formed.

FIGS. 1 to 6 show electron micrographs of the acrylate polymer microsphere aggregate prepared in example 1. As can be seen from the figure, after drying, aggregation and fusion occur between the acrylate polymer microspheres, the surfaces of the microspheres are provided with micropore channels, capillary channels are formed between the microspheres, and the interaction of the micropore channels and the capillary channels enables the acrylate polymer microsphere aggregate to quickly form a high water absorption film after contacting with a substance containing moisture.

The acrylate polymer microsphere aggregate prepared in example 1 was allowed to absorb water to form a film, and then the weight reduction ratio of water in the film was measured as a function of time, and the results are shown in fig. 7. The specific experimental method for determining the weight loss proportion comprises the following steps: weighing 200mg of acrylate polymer powder, placing the acrylate polymer powder in a circular ring with the diameter of 2cm, uniformly spreading, placing the circular ring on qualitative filter paper, spraying water by using a small spraying device to wet the powder to saturation, forming a complete elastic film by the powder under the action of the water after about 2-3 minutes, sucking the water on the surface by using the qualitative filter paper, weighing, and calculating the water absorption rate. And (3) placing the film full of moisture on a clean plastic film, naturally drying, controlling the ambient temperature to be about 25 ℃ and the air humidity to be 30-50%, and periodically weighing and calculating the weight loss rate of the film.

An infrared spectrum of the acrylate polymer microsphere aggregate prepared in example 1 was measured using a Thermo Scientific Nicolet iS10 infrared spectrometer, and the result iS shown in fig. 8, which shows a typical polymethacrylate.

Differential scanning calorimetry was performed on the acrylate polymer microsphere aggregates prepared in example 1 using a PerkinElmer DSC 8000. And (3) testing conditions are as follows: keeping the temperature at-20 ℃ for 2min, heating from-20 ℃ to 150 ℃ at the speed of 20 ℃/min, keeping the temperature at 150 ℃ for 2min, cooling from 150 ℃ to-20 ℃ at the speed of 50 ℃/min, keeping the temperature at-20 ℃ for 3min, and heating from-20 ℃ to 150 ℃ at the speed of 20 ℃/min. The data processing is performed for the two temperature-rising scanning processes, and the result is shown in fig. 9. The first heating scanning process has an obvious endothermic peak, which is caused by vaporization of moisture in air absorbed by the acrylate polymer powder in the heating process, vaporization enthalpy is changed to 113J/g, the second heating scanning process can see obvious glass transition temperature of the acrylate polymer, and Tg is 110.7 ℃.

The particle size distribution and the average particle size of the acrylate polymer microspheres in the aqueous dispersion of step (3) of example 1 were measured using a Malvern Nano ZS ZEN 3600 particle size analyzer, the particle size distribution curve is shown in fig. 10, and the average particle size of the acrylate polymer microspheres was measured to be 93 nm.

Example 2

Preparing an acrylate polymer microsphere aggregate by the following steps:

(1) the preparation process of the core comprises the following steps: 1.5g of SDS emulsifier and 380g of deionized water are weighed into a 500mL four-neck flask respectively, then a stirrer, a nitrogen guide pipe, a thermometer and a condenser are installed, the water bath temperature is maintained at 73 ℃, nitrogen is continuously introduced, stirring is started, a monomer mixture which is weighed in advance and contains 16g of HEMA, 4g of HPMA, 1.5g of MAA and 0.2g of DAAM is added when the emulsifier is completely dissolved and the internal temperature reaches 70 +/-1 ℃, a KPS solution which is dissolved in advance and contains 0.15g of KPS and 20g of deionized water is added after the temperature is stabilized, and the timing is started. After about 5min, the reactants appeared blue, the monomers started to polymerize to form polymer particles, and after about 6h the core preparation reaction was complete.

(2) Respectively weighing 200g of nuclear emulsion and 190g of deionized water into a 500mL four-neck flask, then installing a stirrer, a nitrogen guide pipe, a thermometer and a condenser pipe, maintaining the water bath temperature at 73 ℃, continuously introducing nitrogen and starting stirring, adding a pre-dissolved KPS solution containing 0.15g of KPS and 20g of deionized water when the internal temperature reaches 70 +/-1 ℃, simultaneously beginning to dropwise add an acrylate mixed monomer containing 4g of HEMA, 5g of HPMA, 1.5g of MMA and 0.4g of EGDMA at the speed of 2g/h, and continuing to react for 2h after the monomer is dropwise added, thereby preparing the acrylate nuclear shell emulsion.

(3) The preparation process of the microporous structure comprises the following steps: and (3) adding sodium hydroxide into the acrylate core-shell emulsion prepared in the step (2) to enable the pH value to reach 8, then adding 0.05g of ADH, reacting for 24 hours to obtain water dispersion of the acrylate polymer microsphere with the crosslinked core, and freeze-drying to obtain the acrylate polymer microsphere aggregate.

The polymer particles prepared by adopting the core-shell emulsion polymerization means have the advantages that the core contains a large amount of hydrophilic monomers, the EGDMA in the shell realizes crosslinking, when sodium hydroxide is adopted to neutralize the polymer emulsion, carboxyl in the core is converted into sodium carboxylate, the hydrophilicity is greatly improved, as the difference between the hydrophilicity of the core and the hydrophilicity of the shell is large, the core material and the shell material are intertwined to form an interpenetrating network structure, ADH with equivalent amount to DAAM is added into the system after neutralization is finished, the two react to form a stable interpenetrating network structure, and as the existence of the hydrophilic materials such as the sodium carboxylate, the inside of the polymer particles contains a large amount of moisture. During the subsequent drying process, the micropore channels left by the water loss are retained due to the support of the crosslinking structure, so that the acrylate polymer microsphere aggregate containing a large number of micropore structures is finally formed.

Example 3

Preparing an acrylate polymer microsphere aggregate by the following steps:

(1) the preparation process of the core comprises the following steps: 0.5g of SDS emulsifier and 380g of deionized water are weighed into a 500mL four-neck flask respectively, then a stirrer, a nitrogen guide pipe, a thermometer and a condenser are installed, the water bath temperature is maintained at 73 ℃, nitrogen is continuously introduced, stirring is started, a pre-weighed monomer mixture containing 18g of HEMA, 2g of HPMA, 2.0g of MAA and 0.6g of DAAM is added when the emulsifier is completely dissolved and the internal temperature reaches 70 +/-1 ℃, a pre-dissolved KPS solution containing 0.2g of KPS and 20g of deionized water is added after the temperature is stabilized, and the timing is started. After about 5min, the reactants appeared blue, the monomers started to polymerize to form polymer particles, and after about 6h the core preparation reaction was complete.

(2) The preparation process of the shell comprises the following steps: respectively weighing 180g of nuclear emulsion and 210g of deionized water in a 500mL four-neck flask, then installing a stirrer, a nitrogen guide pipe, a thermometer and a condenser pipe, keeping the water bath temperature at 73 ℃, continuously introducing nitrogen and starting stirring, adding a pre-dissolved KPS solution containing 0.2g of KPS and 20g of deionized water when the internal temperature reaches 70 +/-1 ℃, simultaneously beginning to dropwise add an acrylate mixed monomer containing 3g of HEMA, 6g of HPMA, 2g of MMA and 0.3g of EGDMA at the speed of 1.5g/h, and continuing to react for 2h after the monomer is dropwise added, thereby preparing the acrylate nuclear shell emulsion.

(3) The preparation process of the microporous structure comprises the following steps: and (3) adding sodium hydroxide into the acrylate core-shell emulsion prepared in the step (2) to enable the pH value to reach 8.5, then adding 0.15g of ADH, reacting for 12 hours to obtain an aqueous dispersion of the acrylate polymer microsphere with the crosslinked core, and freeze-drying to obtain the acrylate polymer microsphere aggregate.

The polymer particles prepared by the core-shell emulsion polymerization method of examples 1-3, wherein the core contains a large amount of hydrophilic monomers, and the shell is crosslinked due to the presence of EGDMA, when the polymer emulsion is neutralized by sodium hydroxide, the carboxyl groups in the core are converted into sodium carboxylates, so that the hydrophilicity is greatly improved, the core material and the shell material are intertwined to form an interpenetrating network structure due to the large difference between the hydrophilicity of the core and the hydrophilicity of the shell, after neutralization is completed, ADH equivalent to DAAM is added into the system, and the two react to form a stable interpenetrating network structure, and due to the presence of hydrophilic materials such as sodium carboxylate, the interior of the polymer particles contains a large amount of moisture. During the subsequent drying process, the micropore channels left by the water loss are retained due to the support of the crosslinking structure, so that the acrylate polymer microsphere aggregate containing a large number of micropore structures is finally formed.

Comparative example 1

Preparing an acrylate polymer microsphere aggregate by the following steps:

(1) the preparation process of the core comprises the following steps: respectively weighing 1.0g of SDS emulsifier and 380g of deionized water into a 500mL four-neck flask, then installing a stirrer, a nitrogen guide pipe, a thermometer and a condenser, maintaining the water bath temperature at 73 ℃, continuously introducing nitrogen and starting stirring, adding a pre-weighed monomer mixture containing 12g of HEMA, 8g of HPMA and 1g of MAA when the emulsifier is completely dissolved and the internal temperature reaches 70 +/-1 ℃, adding a pre-dissolved KPS solution containing 0.1g of KPS and 20g of deionized water after the temperature is stabilized, and starting timing. After about 5min, the reactants appeared blue, the monomers started to polymerize to form polymer particles, and after about 6h the core preparation reaction was complete.

(2) The preparation process of the shell comprises the following steps: respectively weighing 210g of nuclear emulsion and 180g of deionized water in a 500mL four-neck flask, then installing a stirrer, a nitrogen guide pipe, a thermometer and a condenser pipe, maintaining the water bath temperature at 73 ℃, continuously introducing nitrogen and starting stirring, adding a pre-dissolved KPS solution containing 0.1g of KPS and 20g of deionized water when the internal temperature reaches 70 +/-1 ℃, simultaneously beginning to dropwise add an acrylate mixed monomer containing 5g of HEMA, 4g of HPMA and 1g of MMA at the speed of 2.5g/h, and continuing to react for 2h after the monomer dropwise addition is finished, thereby preparing the acrylate core-shell emulsion.

(3) The preparation process of the microporous structure comprises the following steps: and (3) adding sodium hydroxide into the acrylate core-shell emulsion prepared in the step (2) to enable the pH value to reach 7.5, obtaining an aqueous dispersion of acrylate polymer microspheres, and freeze-drying to obtain an acrylate polymer microsphere aggregate.

The polymer particles prepared by adopting the core-shell emulsion polymerization means have the advantages that the core contains a large amount of hydrophilic monomers, when sodium hydroxide is adopted to neutralize the polymer emulsion, carboxyl in the core is converted into sodium carboxylate, the hydrophilicity is greatly improved, as the difference between the hydrophilicity of the core and the hydrophilicity of the shell is large, the core substance and the shell substance are intertwined to form an interpenetrating network structure, but as the core layer and the shell layer of the polymer do not contain crosslinkable monomers, a crosslinked structure cannot be formed, in the subsequent drying process, a microporous channel left by water loss is collapsed because the microporous channel is not supported by the crosslinked structure, and finally an acrylate polymer microsphere aggregate containing the microporous structure cannot be formed.

Comparative example 2

Preparing an acrylate polymer microsphere aggregate by the following steps:

(1) the preparation process of the core comprises the following steps: 1.5g of SDS emulsifier and 380g of deionized water are weighed into a 500mL four-neck flask respectively, then a stirrer, a nitrogen guide pipe, a thermometer and a condenser are installed, the water bath temperature is maintained at 73 ℃, nitrogen is continuously introduced, stirring is started, a pre-weighed monomer mixture containing 16g of HEMA, 4g of HPMA, 1.5g of MAA and 0.2g of DAAM is added when the emulsifier is completely dissolved and the internal temperature reaches 70 +/-1 ℃, a pre-dissolved KPS solution containing 0.15g of KPS and 20g of deionized water is added after the temperature is stabilized, and the timing is started. After about 5min, the reactants appeared blue, the monomers started to polymerize to form polymer particles, and after about 6h the core preparation reaction was complete.

(2) The preparation process of the shell comprises the following steps: respectively weighing 200g of nuclear emulsion and 180g of deionized water in a 500mL four-neck flask, then installing a stirrer, a nitrogen guide pipe, a thermometer and a condenser pipe, maintaining the water bath temperature at 73 ℃, continuously introducing nitrogen and starting stirring, adding a pre-dissolved KPS solution containing 0.1g of KPS and 20g of deionized water when the internal temperature reaches 70 +/-1 ℃, simultaneously beginning to dropwise add an acrylate mixed monomer containing 5g of HEMA, 4g of HPMA and 1g of MMA at the speed of 2.5g/h, and continuing to react for 2h after the monomer dropwise addition is finished, thereby preparing the acrylate core-shell emulsion.

(3) The preparation process of the microporous structure comprises the following steps: and (3) adding sodium hydroxide into the acrylate core-shell emulsion prepared in the step (2) to enable the pH value to reach 8, then adding 0.05g of ADH, reacting for 24 hours to obtain water dispersion of the acrylate polymer microsphere with the crosslinked core, and freeze-drying to obtain the acrylate polymer microsphere aggregate.

The polymer particles prepared by adopting the core-shell emulsion polymerization method have the advantages that the core contains a large amount of hydrophilic monomers, when the polymer emulsion is neutralized by adopting sodium hydroxide, carboxyl in the core is converted into sodium carboxylate, the hydrophilicity is greatly improved, as the difference between the hydrophilicity of the core and the hydrophilicity of the shell is larger, the core material and the shell material are intertwined to form an interpenetrating network structure, and after the neutralization is finished, the ADH which is equal to that in the embodiment 2 is added into the system. The DAAM and the ADH react to form a space network structure, but as the shell layer does not form a cross-linked structure, in the subsequent drying process, the micropore channels left by water loss collapse because the micropore channels are not effectively supported by the cross-linked structure of the shell layer, and finally the acrylate polymer microsphere aggregate containing the micropore structure cannot be formed.

Comparative example 3

Preparing an acrylate polymer microsphere aggregate by the following steps:

(1) the preparation process of the core comprises the following steps: weighing 1.5g of SDS emulsifier and 380g of deionized water in a 500mL four-neck flask respectively, then installing a stirrer, a nitrogen guide pipe, a thermometer and a condenser pipe, maintaining the water bath temperature at 73 ℃, continuously introducing nitrogen and starting stirring, adding a pre-weighed monomer mixture containing 16g of HEMA, 4g of HPMA and 1.5g of MAA when the emulsifier is completely dissolved and the internal temperature reaches 70 +/-1 ℃, adding a pre-dissolved KPS solution containing 0.15g of KPS and 20g of deionized water after the temperature is stabilized, and starting timing. After about 5min, the reactants appeared blue, the monomers started to polymerize to form polymer particles, and after about 6h the core preparation reaction was complete.

(2) The preparation process of the shell comprises the following steps: respectively weighing 200g of nuclear emulsion and 180g of deionized water in a 500mL four-neck flask, then installing a stirrer, a nitrogen guide pipe, a thermometer and a condenser pipe, maintaining the water bath temperature at 73 ℃, continuously introducing nitrogen and starting stirring, adding a pre-dissolved KPS solution containing 0.2g of KPS and 20g of deionized water when the internal temperature reaches 70 +/-1 ℃, simultaneously beginning to dropwise add an acrylate mixed monomer containing 5g of HEMA, 4g of HPMA, 1g of MMA and 0.2g of EGDMA at the speed of 1.5g/h, and continuing to react for 2h after the monomer is dropwise added, thereby preparing the acrylate nuclear shell emulsion.

(3) The preparation process of the microporous structure comprises the following steps: and (3) adding sodium hydroxide into the acrylate core-shell emulsion prepared in the step (2) to enable the pH value to reach 8.5 to obtain an aqueous dispersion of acrylate polymer microspheres, and freeze-drying to obtain an acrylate polymer microsphere aggregate.

The polymer particles prepared by adopting the core-shell emulsion polymerization means have the advantages that the core contains a large amount of hydrophilic monomers, when sodium hydroxide is adopted to neutralize the polymer emulsion, carboxyl in the core is converted into sodium carboxylate, the hydrophilicity is greatly improved, as the difference between the hydrophilicity of the core and the hydrophilicity of the shell is large, the core substance and the shell substance are mutually wound to form an interpenetrating network structure, and after neutralization is completed, polymer macromolecules in the core layer can slowly migrate outwards under the help of a water phase because the core layer is not crosslinked, and finally, the core layer and the shell layer generate macroscopic phase separation, so that a high water absorption film with elasticity cannot be formed in the final application process.

Comparative example 4

Preparing an acrylate polymer microsphere aggregate by the following steps:

(1) the preparation process of the emulsion comprises the following steps: 1.5g of SDS emulsifier and 380g of deionized water are weighed into a 500mL four-neck flask respectively, then a stirrer, a nitrogen guide pipe, a thermometer and a condenser are installed, the water bath temperature is maintained at 73 ℃, nitrogen is continuously introduced, stirring is started, a pre-weighed monomer mixture containing 15g of HEMA, 4.5g of HPMA, 1.3g of MAA, 0.2g of DAAM and 0.2g of EGDMA is added when the emulsifier is completely dissolved and the internal temperature reaches 70 +/-1 ℃, a pre-dissolved KPS solution containing 0.15g of KPS and 20g of deionized water is added after the temperature is stabilized, and the timing is started. After about 5min, the reactants appeared blue and the monomers began to polymerize to form polymer particles, after about 6h the reaction was complete.

(2) The preparation process of the microporous structure comprises the following steps: and (2) adding sodium hydroxide into the acrylate emulsion prepared in the step (1) to enable the pH value to reach 8.0, then adding 0.1g of ADH, reacting for 12 hours to obtain an acrylate polymer microsphere dispersion, and freeze-drying to obtain an acrylate polymer microsphere aggregate.

The polymer microsphere aggregate prepared by the steps has a good cross-linking structure, but does not have a microphase separation structure, so that the water-absorbing film formed after meeting water has insufficient elasticity.

Application examples

The acrylic ester polymer microsphere powders prepared in examples 1 to 3 were uniformly shaken on the skin or wound, and a small amount of physiological saline was sprayed thereon to form a highly absorbent film having high elasticity and high strength within about five minutes, so that the transudation of interstitial fluid was reduced with the lapse of time or the healing of the wound, and the highly absorbent film was gradually dried and gradually separated from the skin or the healing wound without adhesion to the skin or the wound.

The acrylate polymer microsphere powders prepared in comparative examples 1 to 4 were uniformly shaken on the skin or wound, and a small amount of physiological saline was sprayed thereon, so that a high water-absorbent film having sufficient elasticity and strength could not be formed, and the formed film was easily broken by external force.