阅读说明：本技术 一种利用木质素磺酸盐制备的纳米胶束及其制备方法 (Nano micelle prepared by using lignosulfonate and preparation method thereof ) 是由 钱晨 方红霞 崔朋 郑娜 郑益燕 于 2019-11-18 设计创作，主要内容包括：本发明提供了一种利用木质素磺酸盐制备的纳米胶束及其制备方法,属于纳米胶束制备技术领域。本发明的方法包括以下步骤：(1)采用温和酸催化法对木质素磺酸盐进行解聚,得到解聚产物；(2)将所述解聚产物进行分离,对分离所得解聚液进行水洗和干燥,得到水不溶物；(3)将所述水不溶物溶解到有机溶剂中,然后加入水,得到纳米胶束；所述水的加入量为有机溶剂体积的20～100倍。本发明通过温和酸催化法解聚木质素磺酸盐,获得除去磺酸盐基团且分子量大幅减小的木质素解聚产物,采用自组装方法制备了木质素磺酸盐解聚产物的纳米胶束,通过控制水的加入量使得到的纳米胶束具有较好的耐酸碱盐的能力,且具有较好的储存稳定性。(The invention provides a nano micelle prepared by using lignosulfonate and a preparation method thereof, belonging to the technical field of nano micelle preparation. The method of the invention comprises the following steps: (1) depolymerizing the lignosulfonate by adopting a mild acid catalysis method to obtain a depolymerized product; (2) separating the depolymerized product, and washing and drying depolymerized liquid obtained by separation to obtain a water-insoluble substance; (3) dissolving the water-insoluble substance into an organic solvent, and then adding water to obtain a nano micelle; the addition amount of the water is 20-100 times of the volume of the organic solvent. The invention depolymerizes the lignosulfonate by a mild acid catalysis method to obtain a lignin depolymerization product with a greatly reduced molecular weight and a removed sulfonate group, prepares the nano micelle of the lignin depolymerization product by a self-assembly method, and controls the addition of water to ensure that the obtained nano micelle has better acid-base salt resistance and better storage stability.)

1. A method for preparing nano-micelle by using lignosulfonate is characterized by comprising the following steps:

(1) depolymerizing the lignosulfonate by adopting a mild acid catalysis method to obtain a depolymerized product;

(2) separating the depolymerized product, and washing and drying depolymerized liquid obtained by separation to obtain a water-insoluble substance;

(3) dissolving the water-insoluble substance into an organic solvent, and then adding water to obtain a nano micelle;

the addition amount of the water is 20-100 times of the volume of the organic solvent.

2. The method of claim 1, wherein the organic solvent comprises acetone, ethanol, methanol, acetonitrile, or tetrahydrofuran.

3. The method according to claim 1 or 2, wherein the concentration of the water-insoluble substance in the organic solvent is 1 to 10 mg/mL.

4. The method according to claim 1, wherein the separation is performed by centrifugation at 5000-10000 rpm.

5. The method of claim 1, further comprising allowing the resulting system to stand and separate after the addition of water.

6. The method of claim 5, wherein the time of resting is below 30 min.

7. A nanomicelle prepared by the method of any one of claims 1 to 6.

8. The nanomicelle according to claim 7, wherein the nanomicelle has a molecular weight of less than 1000Da and an average particle size of 70 to 90 nm.

Technical Field

The invention relates to the technical field of preparation of nano-micelles, in particular to a nano-micelle prepared by lignosulfonate and a preparation method thereof.

Background

Lignin is the most abundant renewable and biodegradable natural resource in the world following cellulose. It is an amorphous polymer formed from phenylpropane units connected by ester and carbon-carbon bonds. The lignin is used as the pulping and papermaking residue, the yield of the lignin is 7000 ten thousand tons every year all over the world, 95 percent of the lignin is used as fuel or discharged along with the black liquor of paper pulp, and only 5 percent of the lignin is used for producing high value-added products, mainly comprising additives, dispersants, adhesives and surfactants. The development of the nano lignin can provide a new way for utilizing the lignin-based products with high added value. Compared with lignin particles of micron and larger scale, the nano lignin particles have larger specific surface area. When mixed with different polymers, the nanoparticles can interact intimately with the polymer matrix, being uniformly distributed in the polymer matrix. The lignin nanoparticles can improve the mechanical property, the thermal stability and the barrier property of the composite material. In addition, research shows that the nano lignin has the characteristics of antibiosis and no cytotoxicity, so that the nano lignin can be used as a substitute product of potential inorganic nano particles and applied to the fields of tissue engineering and regenerative medicine. The common preparation methods of nano lignin are broadly divided into two main categories: the "bottom-up approach" and the "top-down approach". The "bottom-up method" refers to a method of structuring from the bottom, forming a nano-scale material by gradual stacking of atoms, molecules, and clusters. The "top-down method" is to obtain the nano-scale material by conventional grinding and pulverization methods. The production of nano lignin can be roughly classified into a physical method, a chemical method and a comprehensive method according to the type of reaction. The physical method comprises the following steps: sputtering, plasma heating, evaporation-condensation, ball milling, and the like; the chemical method comprises the following steps: sol-gel method, precipitation method, hydrothermal method, self-assembly method, chemical vapor method, and the like; the comprehensive law comprises: supercritical fluid technology and ultrasonic precipitation. Among the most common methods of preparation are sol-gel, supercritical and self-assembly. The lignin with an amphiphilic structure is easy to form nano micelles in a selective solvent, so that the nano-scale lignin is prepared by a self-assembly method. The self-assembly method is to form colloidal spheres by hydrophilic groups such as hydroxyl and carboxyl contained in lignin itself and hydrophobic groups such as benzene rings. Usually, the lignin is completely dissolved in the organic solution, and then water is slowly dripped into the organic solution, so that hydrophobic molecules contained in the lignin slowly self-assemble to form nano colloidal spheres. The self-assembly technology is simple, easy to operate, does not need complex and special devices, and is more environment-friendly by taking water as a solvent. The lignin nanoparticles in the formed solution are uniformly distributed, and the required experimental equipment and raw materials are simple and cheap, so that the method is more suitable for laboratory operation.

However, the lignin nano-micelles prepared by the method require lignin to have an amphiphilic structure, and thus most of the raw materials are lignin with amphiphilicity or strong hydrophobicity, such as alkali lignin and kraft paper lignin. Lignosulfonate, which is a large-content lignin, has strong hydrophilicity due to a large number of sulfonic acid groups, and is hardly applied to the formation of nano micelles.

Disclosure of Invention

The invention aims to provide a nano micelle prepared by using lignosulfonate and a preparation method thereof.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a method for preparing a nano micelle by using lignosulfonate, which comprises the following steps:

(1) depolymerizing the lignosulfonate by adopting a mild acid catalysis method to obtain a depolymerized product;

(2) separating the depolymerized product, and washing and drying depolymerized liquid obtained by separation to obtain a water-insoluble substance;

(3) dissolving the water-insoluble substance into an organic solvent, and then adding water to obtain a nano micelle;

the addition amount of the water is 20-100 times of the volume of the organic solvent.

Preferably, the organic solvent comprises acetone, ethanol, methanol, acetonitrile or tetrahydrofuran.

Preferably, the concentration of the water-insoluble substance in the organic solvent is 1 to 10 mg/mL.

Preferably, the separation mode is centrifugation, and the rotation speed of the centrifugation is 5000-10000 rpm.

Preferably, after the water is added, the obtained system is still placed and separated.

Preferably, the time for the standing is 30min or less.

The invention also provides the nano micelle prepared by the method in the scheme.

Preferably, the molecular weight of the nano micelle is less than 1000Da, and the average particle size is 70-90 nm.

The invention provides a method for preparing a nano micelle by using lignosulfonate, which comprises the following steps: (1) depolymerizing the lignosulfonate by adopting a mild acid catalysis method to obtain a depolymerized product; (2) separating the depolymerized product, and washing and drying depolymerized liquid obtained by separation to obtain a water-insoluble substance; (3) dissolving the water-insoluble substance into an organic solvent, and then adding water to obtain a nano micelle; the addition amount of the water is 20-100 times of the volume of the organic solvent. The invention depolymerizes the lignosulfonate by a mild acid catalysis method to obtain a lignin depolymerization product with a greatly reduced molecular weight and a removed sulfonate group, prepares the nano-micelle of the lignosulfonate depolymerization product by a self-assembly method, controls the addition of water to ensure that the obtained nano-micelle has better acid-base salt resistance and better storage stability, and widens the thought for high-valued application of the lignosulfonate.

Drawings

FIG. 1 is a graph showing the molecular weight and distribution of depolymerization products of example 1;

FIG. 2 is an SEM photograph of the nanomicelle prepared in example 1;

fig. 3 is a TEM photograph of the nanomicelle prepared in example 1.

Detailed Description

The invention provides a method for preparing a nano micelle by using lignosulfonate, which comprises the following steps:

(1) depolymerizing the lignosulfonate by adopting a mild acid catalysis method to obtain a depolymerized product;

(2) separating the depolymerized product, and washing and drying depolymerized liquid obtained by separation to obtain a water-insoluble substance;

(3) dissolving the water-insoluble substance into an organic solvent, and then adding water to obtain a nano micelle;

the addition amount of the water is 20-100 times of the volume of the organic solvent.

In the present invention, the starting materials used are all commercially available products well known in the art, unless otherwise specified.

The invention adopts a mild acid catalysis method to depolymerize the lignosulfonate, so as to obtain a depolymerized product. In the present invention, the mild acid catalysis process is preferably carried out according to step (1) described in the patent application No. 201610643766.0 entitled "process for the isolation of a mild acid catalyzed lignin depolymerization product and its quench extraction product". Wherein, the lignin mild acid catalytic depolymerization product obtained in the step (1) is the depolymerization product of the invention. The invention depolymerizes the lignosulfonate by a mild acid catalysis method, can remove hydrophilic sulfonic acid groups, and changes the depolymerization product from strong hydrophilicity into strong hydrophobicity and weak hydrophilicity; meanwhile, high polymers can be depolymerized into low polymers, and macromolecules are converted into small molecules, so that the nano-micelle can be formed through self-assembly in the follow-up process.

After obtaining the depolymerization product, the invention separates the depolymerization product, and washes and dries the depolymerization liquid obtained by separation to obtain the water-insoluble substance. In the invention, the separation mode is preferably centrifugation, and the rotation speed of the centrifugation is preferably 5000-10000 rpm, and more preferably 6000-7000 rpm. In the present invention, the centrifugation removes residues from the depolymerization reaction product, which are mainly sulfonate salts removed in situ, and which affect the formation of nanomicelles. The invention has no special requirement on the centrifugation time, and can ensure that the residue of depolymerization reaction is removed. The depolymerization product is a thick black solution with good fluidity, and black depolymerization liquid is obtained after separation and residue removal. After the separation, the depolymerization liquid obtained by the separation is washed and dried to obtain the water-insoluble substance. The invention removes water-soluble substances in the depolymerization product by water washing, including phenol, catalyst and non-depolymerized lignosulfonate. In the present invention, the degree of washing with water is preferably such that the pH of the washing solution is neutral. In the present invention, the drying is preferably vacuum drying, and the present invention does not require any special temperature or time for the vacuum drying and can ensure drying of the water-insoluble substance.

After the water-insoluble substance is obtained, the water-insoluble substance is dissolved in an organic solvent, and then water is added to obtain the nano micelle. The invention has no special requirements on the type of the organic solvent, and can completely dissolve the water-insoluble substance. In the present invention, the organic solvent preferably includes acetone, ethanol, methanol, acetonitrile or tetrahydrofuran. In the present invention, the concentration of the water-insoluble substance in the organic solvent is preferably 1 to 10 mg/mL. The present invention does not require any particular means for dissolution, and any means of dissolution known in the art may be used. In the invention, the addition amount of the water is 20-100 times of the volume of the organic solvent, and preferably 20-50 times. The nano micelle obtained by controlling the addition amount of water has better acid-base salt resistance and better storage stability. When the amount of water added is too small, formation of nano-micelles by hydrophobic self-assembly is not facilitated. The invention has no special requirements on the adding mode of the water, and only needs to ensure the water adding amount. Because the depolymerization product is strong hydrophobic and weak hydrophilic, after water is added, hydrophobic molecules contained in the depolymerization product self slowly self-assemble to form nano micelle. Compared with the self-assembly in the prior art, the method has no special requirements on the adding speed and the stirring speed of water, does not need dialysis after the water is added, and is simpler to prepare compared with the existing self-assembly method.

After the addition of water, the present invention preferably further comprises allowing the resulting system to stand and separate. In the present invention, the time for the standing is preferably 30min or less. In the standing process, the depolymerization product is further subjected to self-assembly to form the nano micelle. In the present invention, the separation mode is preferably centrifugation, the rotation speed of the centrifugation is preferably 10000rpm, and the supernatant obtained after the centrifugation comprises the nano micelle of the present invention.

The invention provides the nano micelle prepared by the method in the scheme. In the present invention, the molecular weight of the nanomicelle is preferably less than 1000 Da; the average particle size is preferably 70-90 nm, and more preferably 80 nm; the surface Zeta potential is preferably-41 mV, and the nano-micelle solution can stably exist in a solution with the pH value of 3-13 and the ionic strength of less than 100mM, and the particle size of the nano-micelle solution is not obviously changed after the nano-micelle solution is placed for 1 year.

The present invention will be described in detail with reference to examples, but they should not be construed as limiting the scope of the present invention.