阅读说明：本技术 一种利用葡萄残渣制备黄原胶基自修复水凝胶的方法 (Method for preparing xanthan-based self-repairing hydrogel from grape residues ) 是由 陈厚 丁欣欣 柏良久 蒋红娟 张欣华 王文香 杨华伟 杨丽霞 于 2019-10-05 设计创作，主要内容包括：本发明利用酿酒葡萄残渣提取纤维素纳米晶,基于仿贻贝化学对提取的纤维素纳米晶表面改性设计纤维素纳米晶/聚多巴胺型纳米复合材料。主要利用氯化胆碱、二水合草酸型低共熔溶剂溶解纤维素表面的非晶区提取纤维素纳米晶,在弱碱条件下,利用仿贻贝化学对纤维素纳米晶改性制备纤维素纳米晶/聚多巴胺型纳米复合材料(CNCs@PDA),并所得的的CNCs@PDA植入黄原胶型水凝胶中,制备具有较强机械性能和修复性能的黄原胶基纳米复合水凝胶。(The method utilizes the residues of wine grapes to extract cellulose nanocrystals, and designs the cellulose nanocrystal/polydopamine nanocomposite material based on the surface modification of the extracted cellulose nanocrystals by mussel-like chemistry. Mainly using choline chloride and an oxalic acid dihydrate eutectic solvent to dissolve an amorphous area on the surface of cellulose to extract cellulose nanocrystals, using mussel-like chemistry to modify the cellulose nanocrystals to prepare a cellulose nanocrystal/polydopamine nanocomposite (CNCs @ PDA) under the condition of weak base, and implanting the obtained CNCs @ PDA into xanthan gum type hydrogel to prepare the xanthan gum based nanocomposite hydrogel with strong mechanical property and repairing property.)

1. A method for preparing a xanthan-based self-repairing hydrogel from grape residues is characterized by comprising the following two steps:

(1) preparation of cellulose nanocrystalline/polydopamine type nano composite material by using wine grape residues

Firstly, extracting Cellulose Nanocrystals (CNCs) from wine grape residues, wherein the grape residues comprise benzyl alcohol, sodium chlorite, acetic acid =1 ~: 10: ~ 100:1 ~ 010:1 ~ 1100, the reaction temperature is 50 822100 ℃, the reaction time is 1 ~ hours according to the mass ratio, then holocellulose, sodium hydroxide =1 ~: 410:10 ~ 5100, the reaction temperature is 50 ~ 6100 ℃, the reaction time is 1 ~ hours, then the final product is frozen and dried, extracting the cellulose nanocrystals, namely carrying out acidolysis on the extracted cellulose by using choline chloride and oxalic acid dihydrate to prepare the cellulose nanocrystals, wherein the cellulose, the choline chloride, the oxalic acid dihydrate =0.1 ~: 1 ~: 1 ~, the Tris reaction temperature is 60 ~ 100 ℃, the reaction time is 1: 2 hours, then centrifuging, drying, preparing cellulose nanocrystals by using a chemical dialysis buffer solution =0.1, carrying out a centrifugal precipitation on the surface of the cellulose nanocrystals, the PDA 638, the polysodium chloride;

(2) designing the xanthan-based self-repairing hydrogel by using the prepared CNCs @ PDA:

mixing nano particles CNCs @ PDA with Acrylic Acid (AA), Xanthan Gum (XG), free radical initiator and ferric chloride hexahydrate (FeCl)₃.6H₂O) reacting at a certain temperaturePreparing the nano composite self-repairing hydrogel in time; wherein, according to the mass ratio, CNCs @ PDA: AA: XG: free radical initiator: FeCl₃.6H₂O =0.001 ~ 0.1:1 ~ 100:1 ~ 100:1 ~ 100:1 ~ 10, the free radical initiator is potassium persulfate solution, the reaction temperature is 40 ~ 80 ℃, the test is repeated by changing the using amount of CNCs @ PDA nano particles, the optimal amount is found out by a tensile test, then the hydrogel is subjected to performance characterization such as swelling, scanning electron microscope, infrared and the like, and the hydrogel is subjected to rheological and tensile tests, so that the repair efficiency of the hydrogel is characterized.

2. The xanthan-based self-repairing hydrogel is prepared by applying the cellulose nanocrystal/polydopamine nanocomposite material designed by the method based on wine grape residues.

Technical Field

The invention discloses a method for preparing cellulose nanocrystals by using wine grape residues, a cellulose nanocrystal/polydopamine type nanocomposite (CNCs @ PDA) prepared by modifying the cellulose nanocrystals by using mussel-like chemistry, and a nanocomposite hydrogel with strong mechanical properties and repairing properties by implanting the cellulose nanocrystal/polydopamine type nanocomposite into a xanthan type hydrogel, belonging to the field of functional polymers.

Background

As a soft and wet material consisting of a large amount of water and a three-dimensional cross-linked polymer network, hydrogels have been widely used in the fields of tissue engineering, flexible sensors, drug transport, and the like. However, in practical applications the development of mechanical damage and cracks does not allow the gel material to perform its function for a long time. The development of new functional hydrogels (e.g., self-healing hydrogels, shape memory, responsive hydrogels, etc.) is one of the hot spots of current research. Similar to wound healing in living bodies, self-healing hydrogels are a class of smart gel materials that can restore their functionality after mechanical injury. Due to the self-healing and the function, the service life of the gel material can be prolonged to the maximum extent, and the consumption of limited natural resources can be reduced to the maximum extent. For self-healing hydrogels, the typical healing mechanisms are largely classified into intrinsic and extrinsic categories. Intrinsic means that the self-repairing purpose is achieved through spontaneous recombination of reversible bonds such as hydrogen bonds, metal-ligand coordination complexes, acylhydrazone bonds or imine bonds and the like in the hydrogel. The external aid is a microcapsule or a microvasculature in which a prosthetic agent is incorporated in a material. After the repair agent is released into the matrix, the damage is repaired by filling the fracture or inducing in situ polymerization.

Cellulose Nanocrystals (CNCs) are nanoparticles extracted from cellulose crystalline regions that are biocompatible, lightweight, have a large specific surface area, a high elastic modulus, and good thermal stability. Cellulose nanocrystals can generally be prepared by acid hydrolysis, alkaline hydrolysis, organic solvent processes, oxidation and enzymatic hydrolysis. As a nano material with excellent performance, the cellulose nanocrystal combined with other high polymer materials can be applied to a plurality of fields such as transportation carriers, nano coatings, optical devices and the like. Recently, the application of cellulose nanocrystals in self-healing hydrogels has been widely reported. Tanpichai and the like successfully prepare the CNCs-based reinforced PVA high-water-holding-capacity hydrogel by taking gram A as a cross-linking agent. Shao et al constructed a self-healing cellulose hydrogel with toughness and high resilience from furan-modified CNCs and maleimide-terminated functionalized PEG. The CNCs-based nano composite hydrogel with strong mechanical property and high repair rate is the focus of attention of people.

Bionic mussel chemistry is a green, environmentally friendly chemistry that has been developed in recent years. As a core content of mussel biomimetic chemistry, dopamine can self-polymerize in alkaline solution, forming an adhesive Polydopamine (PDA) coating on the surface of various materials through covalent or non-covalent interactions. The polymerization process is simple and environment-friendly, is almost suitable for all types of material surfaces, and provides a platform with biocompatibility and high adhesiveness for further modification. In addition, PDA can produce strong interaction with some metal ions due to coordination bonding between catechol ligand and metal ions. Han et al utilize dopamine to modify PFS membranes, have better permselectivity while promoting their surface hydrophilicity. Huang et al, which immerse Polyacrylonitrile (PAN) and PSF electrospun fiber membranes in dopamine solution, endow the fiber membranes with good mechanical properties and hydrophilicity.

In the present study, we report a PAA/XG hydrogel with mechanical flexibility and fast self-healing prepared by chemical modification of cellulose nanocrystals extracted from natural waste, wine grape residue, by mussel. In an alkaline environment, the CNCs @ PDA nano material is prepared by forming an adhesive polydopamine coating on the surface of a cellulose nanocrystal through oxidation-auto-polymerization reaction and self-assembly of dopamine. And then mixing other reactants such as CNCs @ PDA, AA, XG solution and the like, and preparing the nano composite hydrogel by adopting an AA-based in-situ free radical polymerization one-pot method. The nano-composite hydrogel effectively improves the mechanical property of the hydrogel under the action of a nano-composite enhancement mechanism, improves the self-repairing efficiency of the hydrogel through a metal coordination effect, greatly overcomes the defects of poor mechanical property and low healing efficiency of the conventional hydrogel, and increases the practical applicability of the hydrogel. In addition, the experiment utilizes natural waste grape residues as the starting raw material for developing novel functional and structural nano materials, so that an effective choice is made for the sustainable development of the society under the condition of not consuming scarce petrochemical raw materials for relieving the global warming problem.

Disclosure of Invention

The invention aims to provide a method for preparing a xanthan-based self-repairing hydrogel from grape residues.

In order to achieve the aim, the invention adopts the specific technical scheme that,

1. a method for preparing a xanthan-based self-repairing hydrogel from grape residues is characterized by comprising the following 2 steps:

(1) preparation of cellulose nanocrystalline/polydopamine type nano composite material by using wine grape residues

Firstly, extracting Cellulose Nanocrystals (CNCs) from wine grape residues, wherein the grape residues comprise benzyl alcohol, sodium chlorite, acetic acid =1 ~: 10 ~: 100:1 ~ 010:1 ~, the reaction temperature is 50 8652100 ℃, the reaction time is 1 ~ hours, the comprehensive cellulose is sodium hydroxide =1 ~: 10 ~, the reaction temperature is 50 ~ 100 ℃, the reaction time is 1 ~ hours, and then the final product is freeze-dried.

And secondly, preparing a nano composite material (CNCs @ PDA) by using mussel-like chemistry, namely, carrying out autopolymerization on dopamine hydrochloride in a Tris-HCl buffer solution (pH = 8.5) environment, depositing the dopamine hydrochloride on the surface of the cellulose nanocrystal to form an adhesive polydopamine coating, so as to prepare the CNCs @ PDA, wherein the fiber nanocrystal comprises the dopamine hydrochloride and the Tris-HCl buffer solution =0.1 ~ 1:0.1 ~ 1:1 ~ 100 in a mass ratio, the reaction temperature is room temperature, the reaction time is 5 ~ 10 hours, and then, carrying out centrifugal washing and freeze drying on the fiber nanocrystal.

(2) Designing the xanthan-based self-repairing hydrogel by using the prepared CNCs @ PDA:

mixing nano particles CNCs @ PDA with Acrylic Acid (AA), Xanthan Gum (XG), free radical initiator and ferric chloride hexahydrate (FeCl)₃.6H₂O) reacting for a certain time at a certain temperature to prepare the nano composite self-repairing hydrogel; wherein, according to the mass ratio, CNCs @ PDA: AA: XG: free radical initiator: FeCl₃.6H₂O =0.001 ~ 0.1:1 ~ 100:1 ~ 100:1 ~ 100:1 ~ 10, wherein the free radical initiator is potassium persulfate solution, the reaction temperature is 40 ~ 80 ℃, the test is repeatedly carried out on the condition that the dosage of CNCs @ PDA nano particles is changed, the optimal dosage is found out through a tensile test, and then the performance characterization such as swelling, scanning electron microscope, infrared and the like is carried out on the obtained hydrogel, and the rheological and tensile tests are carried out on the obtained hydrogel, so that the repair efficiency of the hydrogel is characterized.

2. The xanthan-based self-repairing hydrogel is prepared by applying the cellulose nanocrystal/polydopamine nanocomposite material designed by the method based on wine grape residues.

Accordingly, the present invention claims methods for nanocomposite hydrogels. The method comprises the following steps:

(1) the specific formula of the cellulose nanocrystal/polydopamine-participating xanthan-based self-repairing hydrogel prepared according to the claim 1;

(2) implanting the prepared cellulose nanocrystal/polydopamine nanocomposite (CNCs @ PDA) into xanthan-based self-repairing hydrogel to prepare the nanocomposite hydrogel with stronger mechanical property and repairing property;

due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:

the invention prepares the cellulose nanocrystal by using the wine grape residues for the first time, prepares the cellulose nanocrystal/polydopamine type nanocomposite (CNCs @ PDA) by modifying the cellulose nanocrystal by using the mussel-like chemistry, and implants the cellulose nanocrystal/polydopamine type nanocomposite into the xanthan type hydrogel to prepare the nanocomposite hydrogel with stronger mechanical property and repairing property.

Detailed Description

The invention is further described below with reference to exemplary embodiments, but the invention is not limited to the following embodiments. The method is a conventional method unless otherwise specified. The starting materials are commercially available from the open literature unless otherwise specified.