CN110305232B

CN110305232B - Water-absorbing material based on modified gel polysaccharide and preparation method thereof

Info

Publication number: CN110305232B
Application number: CN201910562172.0A
Authority: CN
Inventors: 韩景芬; 孙英剑; 魏帅; 李青凤; 潘艺文
Original assignee: Inner Mongolia University
Current assignee: Inner Mongolia University
Priority date: 2019-06-26
Filing date: 2019-06-26
Publication date: 2022-05-13
Anticipated expiration: 2039-06-26
Also published as: CN110305232A

Abstract

The invention discloses a water absorbing material based on modified curdlan and a preparation method thereof, which comprises a modification method of curdlan grafting carboxyl compound, wherein the grafted polycarboxylic compound comprises Ethylene Diamine Tetraacetic Acid (EDTA), nitrilotriacetic acid (NTA), Citric Acid (CA), Succinic Acid (SA), Malonic Acid (MA), Oxalic Acid (OA), diethylenetriamine pentaacetic acid (DTPA) and polyglutamic acid (PGLU). The product of the invention has excellent water absorption performance, and the preparation process is green and environment-friendly.

Description

Water-absorbing material based on modified gel polysaccharide and preparation method thereof

Technical Field

The invention belongs to the field of polysaccharide strong water-absorbing materials, relates to a water-absorbing material taking natural polysaccharide as a raw material and a preparation method thereof, and particularly relates to a gel water-absorbing material based on modified gel polysaccharide carboxylation and a preparation method thereof.

Background

The gel water absorption material is a high polymer material with strong water absorption and water locking functions, and strong hydrophilic groups exist in the interior and on the surface of the gel water absorption material. The material has different water absorption performance from common sponge, paper fiber, cotton cloth and the like, the water absorption capacity of the gel material can be hundreds of times or even thousands of times of the self weight, and the self structure expands to form hydrogel with water locking shape.

The water absorbent has wide application prospect in the industrial and agricultural fields of medical treatment and health, agriculture and forestry, gardening, civil construction, daily chemical industry, environmental protection and the like. The traditional water absorption materials, such as absorbent cotton, sponge, napkin, towel and the like used in medical health and daily life, have the problems of small water absorption capacity, poor water retention capacity and the like.

In recent years, polymer materials having good water absorption and moisture retention have attracted much attention as novel water absorbing materials. The high-molecular water-absorbing material is a cross-linked polymer containing carboxyl, hydroxyl and other strong hydrophilic groups, has strong water-absorbing capacity which can reach hundreds to thousands of times of the self-weight, excellent water-retaining property and good processing property and use performance. Before water absorption, the polymer chains are mutually close and twined together and are mutually crosslinked into a net structure, so that the integral fastening is realized. When contacting with water, the water absorbing material contains several hydrophilic groups (such as carboxyl group), so that it is first wetted with water, and then water molecules permeate into the material via capillary action and diffusion action, so that the ionized groups on the chain are ionized in water and the electrostatic repulsion between the same ions makes the polymer chain expand and swell. Due to the requirement of electric neutrality, the counter ions can not migrate to the outside of the polymer, the ion concentration difference between the internal solution and the external solution forms reverse osmosis pressure, and water further enters the water absorbing material under the action of the reverse osmosis pressure to form hydrogel.

However, petroleum-based polymer materials are often non-environment-friendly and have poor biocompatibility, which limits research and application of the petroleum-based polymer materials as water-absorbing materials, especially application of the petroleum-based polymer materials in the field of medical health. Therefore, natural environment-friendly polymer materials are sought to replace synthetic polymers in the petrochemical industry chain, and the development of environment-friendly water-absorbing materials with good biocompatibility is increasingly paid attention. Curdlan is a typical member of the glucan family, is formed by connecting D-glucoses through beta-1, 3 glycosidic bonds, has a unique three-dimensional spiral structure in a main chain, and is an extracellular polysaccharide produced by microbial metabolism. The gel polysaccharide was determined by chemical and enzymatic analysis to be glucose in C₁And C₃An unbranched polysaccharide polymer in which the positions are linked by β -1, 3-glycosidic linkages, the polymer consisting of 300 to 500 glucose residues, having an average degree of polymerization of 450 and a relative molecular weight of about 74000. The polysaccharide backbone can form a more complex three-dimensional structure due to the interaction of the hydroxyl groups within the molecule and the hydrogen bonding between the molecules. In general, curdlan exists in the form of small annular particles, similar to the form of starch. Curdlan is insoluble in water, which greatly limits its application. The gel polysaccharide has a large number of hydroxyl groups in the molecule, so that different groups can be introduced into the repeating unit through chemical modification, and the introduction of the groups can not only improve the solubility of the gel polysaccharide, but also endow the gel polysaccharide with new properties and functionsCan be used. The current water-soluble derivatives of curdlan are reported, which lays a sufficient foundation for research and preparation of curdlan water-absorbing materials.

In conclusion, the traditional water absorbing material has the problems of small water absorbing capacity, poor water retention capacity and the like, the curdlan can be used as a substitute of the traditional synthetic polymer material, the environmental protection and biocompatibility of the water absorbing material are improved, and the application range and the research field of the water absorbing material are further improved.

Disclosure of Invention

The invention discloses a gel polysaccharide water-absorbing material with strong water absorption and provides a preparation method suitable for the water-absorbing material. The preparation method takes curdlan as a framework, grafts substances with multi-carboxyl such as Ethylene Diamine Tetraacetic Acid (EDTA) and the like through amidation reaction, and prepares the curdlan derivative suitable for the water absorbing material through a certain production process.

The technical problem to be solved by the invention is solved by the following scheme: a method for preparing water-absorbing material with curdlan as raw material, reduce curdlan with sodium borohydride to make amino curdlan after nitridizing at first, reuse DIPEA (N, N-diisopropyl ethylamine) to activate and graft polycarboxylic compounds such as Ethylene Diamine Tetraacetic Acid (EDTA), etc., mix polycarboxylic compounds with curdlan, stir, react overnight and dialyze it, freeze-dry after three days, get products.

The invention has the advantages that: 1. the curdlan belongs to colorless, tasteless and nontoxic natural polysaccharide. 2. The water-absorbing material has simple and easy preparation method and high water absorption rate.

The modified gel polysaccharide water-absorbing material has a partial structural formula as follows:

Cur-NTA

Cur-EDTA

Cur-CA

Cur-SA

Cur-MA

Cur-OA

Cur-DTPA

Cur-PGLU

drawings

FIG. 1 is a Fourier infrared transformation diagram of Cur-EDTA which is a Cur-EDTA water absorbent Cur-polysaccharide material according to the present invention;

FIG. 2 is a nuclear magnetic resonance image of Cur-EDTA which is a gel polysaccharide water-absorbing material in the invention;

FIG. 3 is a Fourier infrared transform diagram of Cur-NTA of the curdlan water-absorbing material of the present invention;

FIG. 4 is a nuclear magnetic resonance image of Cur-NTA as a gel polysaccharide water-absorbing material in the invention;

FIG. 5 shows the water-absorbent Cur-CA/Cur-N gel polysaccharide material of the present invention₃Fourier infrared transform plot of/Curdlan;

FIG. 6 is a nuclear magnetic resonance image of Cur-CA which is a gel polysaccharide water-absorbing material in the invention;

FIG. 7 is a comparison graph of water absorption capacity of Cur-EDTA as a gel polysaccharide water absorbing material in the present invention;

FIG. 8 is a comparison graph of water absorption capacity of Cur-NTA, a Cur-NTA water absorbent material according to the present invention;

FIG. 9 is a comparison graph of the water absorption capacity of Cur-CA which is a gel polysaccharide water-absorbing material in the present invention;

Detailed Description

For a further understanding of the contents, features and effects of the invention, reference is made to the following examples, which are set forth in the accompanying drawings and in the following detailed description:

example 1:

a method for preparing a water absorbing material by taking curdlan and Ethylene Diamine Tetraacetic Acid (EDTA) as raw materials comprises the following steps:

(1) taking 0.3g of curdlan (vacuum drying overnight in advance) to be placed in a reactor, adding DMF to dissolve, stirring in an oil bath to fully dissolve, reacting for 30min, adding 0.93g of NaN3 solution to be stirred in a constant-temperature oil bath, adding triphenylphosphine and carbon tetrabromide to react for 40h, then precipitating with anhydrous methanol, respectively precipitating with anhydrous methanol, anhydrous ethanol and distilled water by centrifugation for 3 times, and finally drying in a vacuum oven to obtain a sample, which is marked as Cur-N₃；

(2) Taking Cur-N₃Adding DMSO into a reactor to dissolve, and then adding NaBH with a molar ratio of 12:1₄Stirring in oil bath at constant temperature, reacting overnight, adding anhydrous ethanol, reacting, centrifuging, washing, dialyzing in dialysis bag for 3 days, rotary steaming, lyophilizing, and recording as Cur-NH₂；

(3) Dissolving Ethylene Diamine Tetraacetic Acid (EDTA) in DMSO in a round-bottom flask, respectively weighing EDC (1- (3-dimethylaminopropyl) -3-ethylcarbodiimide) and NHS (N-hydroxysuccinimide), mixing the two solutions, adding DIPEA (N, N-diisopropylethylamine) for activation, wherein Cur-NH₂EDTA EDC NHS DIPEA =1:2.5:3:3:3 (molar ratio), and Cur-NH formed in (2)₂Reacting for three days and three nights under the protection of nitrogen, dialyzing in a distillation environment, and performing rotary evaporation and freeze-drying to finally generate a milky water-soluble substance which is the prepared water absorbing material and is recorded as Cur-EDTA;

(4) please refer to fig. 1 and fig. 2, which are the fourier transform diagram and the nmr spectrum of Cur-EDTA, respectively, wherein the fourier transform diagram is 1716cm^-1Carbonyl group ofTelescopic vibration peak 1662 cm^-1N-H stretching vibration peak of (1), 1405 cm^-1The C-N stretching vibration peak and the peak of carbonyl carbon at the position with the shift of 175ppm in a nuclear magnetic resonance carbon spectrogram prove that the EDTA modified gel polysaccharide derivative is successfully synthesized. Meanwhile, the material has good water absorption rate which can reach 1400 times of the mass of the material, so that the material has good potential application value on water-absorbable materials.

Example 2:

a method for preparing water-absorbing material by taking curdlan and nitrilotriacetic acid (NTA) as raw materials comprises the following steps:

(1) same as in step (1) of example 1;

(2) same as in step (2) of example 1;

(3) firstly, nitrilotriacetic acid (NTA) is added into a round-bottom flask, DMSO is added to be fully dissolved, EDC (1- (3-dimethylaminopropyl) -3-ethylcarbodiimide) and NHS (N-hydroxysuccinimide) are respectively weighed and mixed to be added, DIPEA (N, N-diisopropylethylamine) is added to be activated, wherein Cur-NH₂NTA EDC NHS DIPEA =1:2.5:3:3:3 (molar ratio), and Cur-NH formed in (2)₂Reacting for three days and three nights under the protection of nitrogen, dialyzing in a distillation environment, and performing rotary evaporation and freeze-drying to finally generate a milky water-soluble substance which is the prepared water absorbing material and is recorded as Cur-NTA;

(4) please refer to fig. 3 and fig. 4, which are the fourier transform plot and the nmr spectrum plot of Cur-NTA, respectively, wherein the fourier transform plot is 1716cm^-1The stretching vibration peak of carbonyl of (1) is 1662 cm^-1(ii) N-H stretching vibration peak of 1405 cm^-1The stretching vibration peak of C-N and the peak of carbonyl carbon at the position with the shift of 175ppm in a nuclear magnetic resonance carbon spectrogram prove that the NTA modified gel polysaccharide derivative is successfully synthesized. The water absorbing material has the same water absorbing effect as the water absorbing material in the embodiment 1, the maximum water absorbing capacity can reach 1500 times of the self weight, and the water absorbing material has good potential application value.

Example 3:

a method for preparing a water absorbing material by taking curdlan and Citric Acid (CA) as raw materials comprises the following steps:

(1) same as in step (1) of example 1;

(2) same as in step (2) of example 1;

(3) firstly, Citric Acid (CA) is put into a round-bottom flask, DMSO is added to be fully dissolved, EDC (1- (3-dimethylaminopropyl) -3-ethylcarbodiimide) and NHS (N-hydroxysuccinimide) are respectively weighed and mixed to be added, DIPEA (N, N-diisopropylethylamine) is added to be activated, wherein Cur-NH₂EDC, NHS, DIPEA =1:2.5:3:3:3 (molar ratio), and Cur-NH formed in (2)₂Reacting for three days and three nights under the protection of nitrogen, dialyzing in a distillation environment, and performing rotary evaporation and freeze-drying to finally generate a milky water-soluble substance which is the prepared water absorbing material and is marked as Cur-CA;

(4) please refer to fig. 5 and fig. 6, which are the fourier transform plot and the nmr spectrum of Cur-CA, respectively, wherein the fourier transform plot is 1716cm^-1Stretching and contracting carbonyl group vibration peak of 1662 cm^-1(ii) N-H stretching vibration peak of 1405 cm^-1The C-N stretching vibration peak and the peak of carbonyl carbon at the position with the shift of 175ppm in a nuclear magnetic resonance carbon spectrogram prove that the CA modified gel polysaccharide derivative is successfully synthesized. The water absorbing material has the same water absorbing effect as the water absorbing material in the embodiment 1, has the highest water absorbing capacity of 1300 times of the self weight, and has good potential application value.

Claims

1. A preparation method of a water absorbing material based on modified curdlan comprises the steps of nitridizing curdlan, reducing the curdlan by using sodium borohydride to prepare amino curdlan, activating and grafting a polycarboxyl compound by using N, N-diisopropylethylamine, mixing the polycarboxyl compound with the curdlan, stirring uniformly, reacting overnight, dialyzing the mixture, and freeze-drying the mixture after three days to obtain the water absorbing material;

the polycarboxyl compound is nitrilotriacetic acid.

2. The water-absorbing material based on modified curdlan prepared by the preparation method of claim 1, wherein the water-absorbing material has the following structural formula R:

Cur-NTA