阅读说明：本技术 一种表面离子液体功能化聚合物微球的制备方法 (Preparation method of surface ionic liquid functionalized polymer microspheres ) 是由 陈冬 梁灏 罗天净 马育红 杨万泰 张先宏 于 2020-06-05 设计创作，主要内容包括：本发明公开了一种表面离子液体功能化聚合物微球的制备方法,属于聚合物微球技术领域。本发明采用分散聚合的方法,使用离子液体单体作为可聚合型稳定剂,成功制备了表面离子液体功能化的单分散聚合物微球,将离子液体独特的物化性能和单分散聚合物微球的优点结合起来,拓宽了离子液体的应用范围,提供了一种成本低廉,操作简便的功能性聚合物微球制备新方法,为离子液体的工业化应用提供了新思路。(The invention discloses a preparation method of surface ionic liquid functionalized polymer microspheres, belonging to the technical field of polymer microspheres. The invention adopts a dispersion polymerization method, uses ionic liquid monomer as a polymerizable stabilizer, successfully prepares monodisperse polymer microspheres with functionalized surface ionic liquid, combines the unique physical and chemical properties of the ionic liquid with the advantages of the monodisperse polymer microspheres, widens the application range of the ionic liquid, provides a novel method for preparing the functional polymer microspheres with low cost and simple and convenient operation, and provides a novel idea for the industrial application of the ionic liquid.)

1. A preparation method of surface ionic liquid functionalized polymer microspheres is characterized by comprising the following steps: the method adopts a dispersion polymerization technology, takes an ionic liquid monomer as a polymerizable stabilizer to prepare the surface ionic liquid functionalized polymer microsphere, and a dispersion polymerization system consists of the monomer, the ionic liquid monomer, an initiator and a solvent, and comprises the following specific steps:

(1) firstly, dissolving and dispersing an ionic liquid monomer and an oil-soluble monomer in a polar organic solvent, and adding a proper amount of water under the stirring condition to form a dispersion polymerization system;

(2) secondly, adding an initiator under the protection of inert gas, heating the reaction system to 60-90 ℃, and polymerizing for 3-6 hours under the conditions of constant temperature and proper stirring;

(3) and after the reaction is finished, separating the polymer microspheres from the reaction system through centrifugal separation, washing and drying to obtain the surface ionic liquid functionalized polymer microspheres.

2. The method according to claim 1, wherein the surface ionic liquid functionalized polymer microspheres are prepared by dispersion polymerization, wherein the monomers in the dispersion polymerization system are common oil-soluble monomers and are composed of one or more of styrene monomers, acrylate monomers and methacrylate monomers, and the volume percentage concentration of the monomers in the reaction system is 5-30 vol%.

3. The method according to claim 1, wherein the surface ionic liquid functionalized polymer microspheres are prepared by dispersion polymerization, wherein ionic liquid monomers in the dispersion polymerization system comprise one or more of 2-acrylamido-2-methyl (triethylamine) propanesulfonate (AMPS-TEA), 1-vinyl-3-butylimidazole bistrifluoromethanesulfonylimide, 1-vinyl-3-butylimidazole bromide, 1-vinyl-3-ethylimidazole nitrate and 1-vinyl-3-butylimidazole hexafluorophosphate, and the amount of the ionic liquid monomers in the reaction system is 0.1-7 wt% of the mass of the monomers.

4. The method according to claim 1, wherein the surface ionic liquid functionalized polymer microspheres are prepared by dispersion polymerization, wherein an initiator in a dispersion polymerization system is composed of one or more of azo-type and peroxide-type free radical initiators, and the amount of the initiator in the system is 0.3-5 wt% of the mass of the monomer.

5. The method according to claim 1, wherein the surface ionic liquid functionalized polymer microspheres are prepared by dispersion polymerization, a solvent in a dispersion polymerization system consists of a polar organic solvent and water, the organic solvent consists of one or more of methanol, ethanol, ethylene glycol, glycerol, acetone, butanone, tetrahydrofuran and dioxane, and the water content in the system is 5-35 vol%.

6. The method as claimed in claim 1, wherein the surface ionic liquid functionalized polymer microspheres are prepared by dispersion polymerization, and a cross-linking agent can be further introduced into the dispersion polymerization system, wherein the cross-linking agent is a bifunctional or polyfunctional monomer and is composed of one or more of aromatic divinyl compounds, bifunctional or polyfunctional (meth) acrylate, allyl (meth) acrylate and conjugated diene; the dosage of the cross-linking agent is 1-20 wt% of the mass of the monomer.

7. The method of claim 1, wherein the surface ionic liquid functionalized polymer microspheres are prepared by dispersion polymerization, and the particle size of the prepared polymer microspheres is 0.1-2.8 μm.

Technical Field

The invention relates to a preparation method of polymer microspheres, in particular to a preparation method of surface ionic liquid functionalized polymer microspheres.

Background

The ionic liquid is an ionic compound composed of an organic cation and an inorganic or organic anion, and is also called a room-temperature ionic liquid, a room-temperature molten salt, an ionic melt, or an organic ionic liquid because it is in a liquid state at or near room temperature. However, since it exists in a liquid state over a wide temperature range, the processability is poor, and practical application of the ionic liquid is greatly limited.

The ionic liquid polymer can combine the unique physical and chemical properties of the ionic liquid with the advantages of the polymer, and broadens the application range of the ionic liquid, such as Hejun Gao and the like (Hejun Gao, Yun Wang, Liqiangzheng, hydroxyl-functionalized ionic liquid-based cross-linked polymers, ashighly effective absorbent for establishing azo dyes removal [ J ] chemical engineering journal.2002,234:372 and 379) by adopting hydroxyl-functionalized ionic liquid monomer 1-hydroxyethyl-3-vinyl imidazole hydrochloride to perform cross-linking polymerization reaction with multi-functional monomer divinylbenzene, and successfully prepare the functional ionic liquid polymer PDVB-IL-OH which can be used as a high-efficiency adsorption material for adsorption and removal of anionic azo dyes. However, the cost of ionic liquid monomer is expensive, which greatly limits the practical application of polyionic liquid, and the related research at present is limited, on the other hand, for polyionic liquid material, most of ionic liquid groups are embedded in the polymer body, and the excellent performance of the ionic liquid groups cannot be effectively exerted, so that the development of a low-cost surface ionic liquid functionalized polymer microsphere, especially a preparation method of the surface ionic liquid functionalized polymer microsphere with uniform and controllable appearance and size, is urgently needed.

Because of the unique physicochemical properties of small size, large specific surface area, uniform particle size distribution, good chemical stability and the like, the monodisperse polymer microspheres, in particular the functional monodisperse polymer microspheres have wide application prospects in the fields of chromatographic separation, drug controlled release, biological detection, enzyme immobilization, photonic crystals, electronic information materials and other leading-edge materials. Such as: the polystyrene fluorescent microspheres with the particle size of about 1-100 mu m are widely applied to the fields of protein, gene and other biomolecule carriers, high-efficiency chromatographic column packing, functional coating, cosmetic whitening packing and the like. In view of important academic value and wide application prospect, the synthesis and preparation of the monodisperse polymer microsphere is always a research hotspot in the field of polymer science.

At present, the preparation of monodisperse polymer microspheres mainly adopts methods such as common emulsion polymerization, microemulsion polymerization, miniemulsion polymerization, dispersion polymerization and the like, and for emulsion and dispersion polymerization, a certain amount of surfactant (emulsifier or stabilizer) needs to be added into a reaction system in order to maintain the stability of the polymerization process and prevent the microspheres from aggregating and settling. The introduction of the surfactant not only affects the purity and performance of the microsphere product, but also causes environmental pollution to a certain extent, and greatly restricts the application of the polymer microsphere, especially the application in the fields of chromatographic separation, biomedicine and the like. Considering that the ionic liquid monomer is composed of hydrophobic organic cations and inorganic or organic anions with certain hydrophilicity, has excellent surface activity, and can be used as a surface active monomer to be applied to a dispersion polymerization system so as to overcome the defects of the conventional surfactant. And as a surface active substance, the ionic liquid monomer can be enriched on the surface of the polymer microsphere, so that the ionic liquid monomer can be 'fixed' on the surface of the polymer microsphere through polymerization, and the prepared ionic liquid functionalized polymer microsphere can greatly improve the utilization efficiency of the ionic liquid and reduce the cost. Therefore, the preparation method of the surface ionic liquid functionalized polymer microspheres based on ionic liquid monomers and dispersion polymerization is simple and convenient to develop and operate, mild in process conditions and uniform and controllable in size and appearance of the microspheres, and has important theoretical and practical values.

Disclosure of Invention

The invention aims to provide a preparation method of surface ionic liquid functionalized polymer microspheres based on ionic liquid monomers, so as to solve the problems and the defects in the background technology.

Based on the analysis of ionic liquid monomers and the reaction mechanism of a dispersion polymerization system in the background technology, the specific thought of the invention is as follows: by adopting a dispersion polymerization method, an ionic liquid monomer is taken as a polymerizable surface active substance, aggregation and sedimentation of the formed polymer microspheres are prevented under the action of electrostatic repulsion, and the stability of the polymerization process is maintained, so that the preparation of the surface ionic liquid functionalized polymer microspheres is realized.

Specifically, an ionic liquid monomer is taken as a polymerizable stabilizer, and a dispersion polymerization technology is adopted to prepare the surface ionic liquid functionalized polymer microsphere, and the method specifically comprises the following steps:

(1) first, an ionic liquid monomer and an oil-soluble monomer are dissolved and dispersed in a polar organic solvent, and an appropriate amount of water is added under stirring to form a dispersion polymerization system.

The monomer in the dispersion polymerization system is a conventional oil-soluble monomer and consists of one or more of styrene monomers (styrene, alpha-methyl styrene, p-methyl styrene, ethyl styrene, p-methoxy styrene and the like), acrylate monomers (methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate and the like) and methacrylate monomers (methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, tert-butyl methacrylate, hexyl methacrylate and the like), wherein the volume percentage concentration of the monomer in the reaction system is 5-30 vol%, and the preferred volume percentage concentration of the monomer is 5-15 vol%.

The surface ionic liquid functionalized polymer microspheres are prepared by adopting dispersion polymerization, wherein a surface active monomer in a dispersion polymerization system is an ionic liquid monomer, the selected ionic liquid monomer is one or more of 2-acrylamido-2-methyl (triethylamine) propanesulfonate (AMPS-TEA), 1-vinyl-3-butylimidazole bistrifluoromethanesulfonylimide salt, 1-vinyl-3-butylimidazole bromide salt, 1-vinyl-3-ethylimidazole nitrate and 1-vinyl-3-butylimidazole hexafluorophosphate, and the dosage of the ionic liquid monomer in a reaction system is 0.1-7 wt% of the mass of an oil-soluble monomer, preferably 0.5-6 wt% of the mass of the oil-soluble monomer.

The solvent of the dispersion polymerization system consists of a polar organic solvent and water, wherein the polar organic solvent consists of one or more of methanol, ethanol, ethylene glycol, glycerol, acetone, butanone, tetrahydrofuran, dioxane and acetic acid, and the amount of water in the system is 5-35 vol% of the total volume of the solvent, preferably 15-30 vol%.

(2) Secondly, adding an initiator under the protection of inert gas, heating the reaction system to 50-90 ℃ to initiate polymerization, preferably 65-80 ℃ to carry out polymerization, and reacting for 3-6 hours under the conditions of constant temperature and proper stirring.

The initiator used in the dispersion polymerization system is a radical initiator known to those skilled in the art, and may be composed of one or more of azo type initiators, peroxide initiators, redox initiation systems. The azo initiator comprises: azobisisobutyronitrile (AIBN), azobisisopentylcyanide, Azobisisoheptylcyanide (ABVN), dimethyl azobisisobutyrate, and the like; the peroxide initiator comprises: dibenzoyl peroxide (BPO), diisobutyryl peroxide, t-butyl peroxyacetate, dicumyl peroxide, bis (2, 4-dichlorobenzoyl) peroxide, di-t-butyl peroxide, lauroyl peroxide, t-butyl peroxyneoheptanoate, t-butyl peroxypivalate, cumyl peroxyneodecanoate, t-butyl peroxyneodecanoate, and the like; the redox initiator includes: benzoyl Peroxide (BPO)/N, N-dimethyl-p-toluidine (DMT), Benzoyl Peroxide (BPO)/N, N-bis (2-hydroxyethyl) -p-toluidine (DHET), and the like. The amount of the initiator in the polymerization system is 0.3-5 wt% of the mass of the monomer, preferably 0.5-3 wt%.

(3) And after the reaction is finished, centrifugally separating the polymerization product, separating the prepared polymer microspheres from the reaction system, washing and drying to obtain the surface ionic liquid functionalized polymer microspheres.

The dispersion polymerization system can be further added with a cross-linking agent to prepare surface ionic liquid functionalized cross-linked polymer microspheres, wherein the cross-linking agent can be a bifunctional or polyfunctional monomer and consists of one or more of aromatic divinyl compounds, bifunctional or polyfunctional (methyl) acrylate, allyl (methyl) acrylate and conjugated diene; the aromatic divinyl compound is a meta-divinylbenzene, para-divinylbenzene mixture (DVB), wherein DVB may be DVB-55 with a divinylbenzene content of 55% or DVB-80 with a divinylbenzene content of 80%; the bifunctional or polyfunctional (meth) acrylate includes, for example, a product obtained by esterifying both terminal hydroxyl groups of ethylene glycol or an oligomer thereof such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate with acrylic acid or methacrylic acid, a product obtained by esterifying both terminal hydroxyl groups of propylene glycol or an oligomer thereof with acrylic acid or methacrylic acid, a product obtained by esterifying the hydroxyl groups of a diol such as neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, butanediol di (meth) acrylate with acrylic acid or methacrylic acid, an ethylene oxide or epichlorohydrin adduct of bisphenol A, or a halogen-substituted product thereof, acrylic acid or methacrylic acid esterification products of polyhydric alcohols such as trimethylolpropane, pentaerythritol, and the like, addition products (epoxy ring-opening addition products) of 2 or more hydroxyl groups or amine groups of amino compounds with glycidyl acrylate or glycidyl methacrylate, reaction products of glycidyl acrylate or glycidyl methacrylate with succinic acid, adipic acid, terephthalic acid, phthalic acid, ethylene glycol addition products of the above dibasic acids or halogen substitutes by epoxy ring-opening addition; the conjugated diene comprises 1, 4-butadiene, isoprene, C5 fraction, dicyclopentadiene and the like; among them, DVB-55, DVB-80, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate and neopentyl glycol dimethacrylate are preferably used. In order to ensure the crosslinking degree of the particles and prevent the widening of the particle size distribution caused by the generation of secondary particles in the system, the amount of the crosslinking agent is 1-20 wt%, preferably 1-5 wt% of the mass of the monomer.

The reason for preparing the surface ionic liquid functionalized polymer microspheres by adopting the dispersion polymerization process is that compared with a common polymerization system, the dispersion polymerization system can obtain polymer particles with the particle size distribution of monodispersion, the polymerization reaction speed is high, the yield is high, the product is easy to separate, and the particle size of the prepared polymer microspheres can be conveniently controlled (the particle size range is 100-1500 nm) through an initiation system, the reaction temperature and the monomer concentration adjustment.

Specifically, the reaction system formula and the operation steps for preparing the surface ionic liquid functionalized polymer microspheres by using styrene as a monomer, AMPS-TEA as an ionic liquid monomer and AIBN as an initiator are as follows (taking the monomer concentration of 10 vol% as an example).

Monomer (b): styrene (St)5.0 mL; AMPS-TEA0.0453g;

initiator: 0.0906g of Azobisisobutyronitrile (AIBN);

solvent: 31.5mL of ethanol and 13.5mL of deionized water.

The operation steps are as follows:

dissolving the mixed monomer in 31.5mL of ethanol and 13.5mL of deionized water to prepare a mixed solution with the monomer concentration of 10 vol%, dissolving 0.0906g of initiator AIBN in the mixed solution, introducing nitrogen for 15min to remove oxygen in the system, and then heating the solution to 65-90 ℃ for reaction for 8 h. After the reaction is finished, centrifuging the reaction product for 10min at the rotating speed of 4000r/min, washing the reaction product by using methanol, centrifuging the reaction product for three times, and drying the reaction product in vacuum at room temperature to constant weight to obtain the surface ionic liquid functionalized polymer microsphere.

The conversion rate of the product is measured by gravimetric calculation; the morphology of the microspheres was observed by a Scanning Electron Microscope (SEM), the particle diameters of at least 100 microspheres were measured using software from SEM photographs of the obtained samples, and the average particle diameter (D) of the microspheres was calculated via the following formula_n) And the Coefficient of Variation (CV) of the particle size distribution, the formula is as follows:

wherein D_iIs the diameter of the ith microsphereN is the total number of microspheres, D_nIs a defined number average particle size.

The surface ionic liquid functional polymer microsphere prepared by the invention has the average particle size of 670-2880nm and the particle size variation coefficient of 1-10%, is a monodisperse or nearly monodisperse polymer microsphere, can effectively control the size of the polymer microsphere through changing the conditions such as monomer concentration, temperature and the like, and can simply control the content of the functional ionic liquid in the polymer microsphere through changing the composition of a polymerization system.

Compared with the prior art, the invention has the beneficial effects and advantages that:

(1) the preparation method of the surface ionic liquid functionalized polymer microspheres combines the unique physical and chemical properties of ionic liquid and the advantages of the polymer microspheres, and widens the application field of the ionic liquid.

(2) The invention adopts a dispersion polymerization method, uses ionic liquid monomer as a polymerizable stabilizer to prepare the monodisperse surface ionic liquid functionalized polymer microspheres with the particle size of micron grade, and has mild reaction conditions and simple operation process.

(3) The surface ionic liquid functionalized polymer microspheres prepared by the method have uniform regular shape and size and good monodispersity, and can realize effective regulation and control of the shape and size through changing conditions such as monomer concentration, temperature and the like.

Drawings

FIG. 1 is an infrared spectrum of a surface ionic liquid functionalized polymer microsphere (PS-AMPS-TEA).

FIG. 2 is a scanning electron micrograph of surface ionic liquid functionalized polymer microspheres prepared under different AMPS-TEA concentrations: (a)0.1 wt%; (b)0.25 wt%; (c)0.5 wt%; (d)2 wt%; (e)3 wt%; (f)4 wt%; (g)5 wt%; (h)6 wt%; (i)7 wt%. Other reaction parameters: the concentration of the monomer St is 10 vol%, the dosage of the initiator AIBN is 2 wt% of the mass of the monomer, and the dispersion medium is ethanol solution with the water content of 30 vol%.

FIG. 3 is a scanning electron micrograph of surface ionic liquid functionalized polymer microspheres prepared with different St monomer concentrations; (a)5 vol%; (b)15 vol%; (c)20 vol%; (d)25 vol%. Other reaction parameters: the amount of AMPS-TEA used was 2 wt% based on the mass of the monomer, the amount of AIBN used was 2 wt% based on the mass of the monomer, and the dispersion medium was an ethanol solution having a water content of 30 vol%.

FIG. 4 is an SEM photograph of surface ionic liquid functionalized polymer microspheres prepared in dispersion media with different water contents: (a)5 vol%; (b)10 vol%; (c)15 vol%; (d)20 vol%; (e)25 vol%; (f)35 vol%. Other reaction parameters: AMPS-TEA was used in an amount of 2% by weight based on the mass of the monomer, AIBN was used in an amount of 2% by weight based on the mass of the monomer, and the concentration of St as a monomer was 10 vol%.

Detailed Description

The technical solution of the present invention will be clearly and completely described below with reference to the following examples, which, however, do not limit the present invention. All other results, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.