阅读说明：本技术 一种梯度水凝胶软驱动器的制备方法及应用 (preparation method and application of gradient hydrogel soft driver ) 是由 常春雨 莫康伟 张俐娜 于 2019-08-22 设计创作，主要内容包括：本发明涉及复合材料、高分子功能材料的技术领域,具体涉及一种梯度水凝胶软驱动器的制备方法及应用。梯度水凝胶软驱动器的制备方法为将一定量带负电的海鞘纤维素纳米晶体、N-异丙烯丙烯酰胺、助剂和水在一定温度下混合均匀,得到混合溶液；并将混合溶液经直流电场诱导,然后原位热引发聚合制备梯度水凝胶软驱动器。本发明的梯度水凝胶软驱动器,由海鞘纤维素纳米晶体与聚N-异丙烯丙烯酰胺复合而成。带负电的海鞘纤维素纳米晶体由于受到电场力而运动形成梯度浓度,最后在原位引发聚合形成具有梯度交联结构的水凝胶软驱动器。本发明的水凝胶软驱动器具有可控的温敏弯曲速率以及抗疲劳性。(The invention relates to the technical field of composite materials and high-molecular functional materials, in particular to a preparation method and application of a gradient hydrogel floppy drive. The preparation method of the gradient hydrogel floppy drive comprises the steps of uniformly mixing a certain amount of negatively charged sea squirt cellulose nanocrystals, N-isopropylacrylamide, an auxiliary agent and water at a certain temperature to obtain a mixed solution; and inducing the mixed solution by a direct current electric field, and then preparing the gradient hydrogel soft driver by in-situ thermal initiation polymerization. The gradient hydrogel soft driver is formed by compounding ascidian cellulose nanocrystals and poly-N-isopropylacrylamide. The negatively charged sea squirt cellulose nanocrystals move to form gradient concentration due to the electric field force, and finally the hydrogel soft driver with the gradient cross-linked structure is formed by in-situ initiated polymerization. The hydrogel soft driver has controllable temperature-sensitive bending rate and fatigue resistance.)

1. A preparation method of a gradient hydrogel floppy drive is characterized by comprising the following steps: uniformly mixing a certain amount of negatively charged sea squirt cellulose nanocrystals, N-isopropylacrylamide, an auxiliary agent and water at a certain temperature to obtain a mixed solution; and inducing the mixed solution by a direct current electric field, and then preparing the gradient hydrogel soft driver by in-situ thermal initiation polymerization.

2. The method of making a gradient hydrogel floppy drive according to claim 1, characterized in that: the concentration of the N-isopropamide in the mixed solution is 11.3 wt%, and the content of the ecteinascidin cellulose nanocrystals accounts for 1-5 wt% of the content of the N-isopropamide.

3. The method of making a gradient hydrogel floppy drive according to claim 1, characterized in that: the auxiliary agent comprises potassium persulfate, N, N-methylene-bisacrylamide and tetramethylethylenediamine, wherein the content of the potassium persulfate accounts for 0.96 wt% of the content of the N-isopropanolamide, the content of the N, N-methylene-bisacrylamide accounts for 0.33 wt% of the content of the N-isopropanolamide, and the content of the tetramethylethylenediamine accounts for 0.53% ml/g of the content of the N-isopropanolamide.

4. The method of making a gradient hydrogel floppy drive according to claim 1, characterized in that: mixing the sea squirt cellulose nanocrystals with negative electricity, N-isopropylacrylamide and an auxiliary agent at a certain temperature at 0-4 ℃, and inducing by a direct current electric field.

5. The method of making a gradient hydrogel floppy drive according to claim 1, characterized in that: the strength of the direct current electric field is 0.5-2V/mm.

6. The method of making a gradient hydrogel floppy drive according to claim 1, characterized in that: the induction time of the direct current electric field is 15-60 min.

7. The method of making a gradient hydrogel floppy drive according to claim 1, characterized in that: the temperature of the in-situ thermal initiation polymerization reaction is 18-25 ℃.

8. The method of making a gradient hydrogel floppy drive according to claim 1, characterized in that: the method further comprises the following step of immersing a product into water at room temperature until swelling equilibrium is reached after the in-situ thermal-initiated polymerization reaction is completed, so as to obtain the gradient hydrogel floppy drive.

9. The method of making a gradient hydrogel floppy drive according to claim 1, characterized in that: the gradient hydrogel soft driver has the equilibrium swelling ratio of 34.5-40.6 g/g, the bending angle of-180 degrees in water at 40 ℃, the bending rate of 0-5.4 degrees/s in water at 40 ℃ and the recovery rate of 0-1.5 degrees/s in water at 25 ℃.

10. Use of a gradient hydrogel floppy drive prepared according to the preparation method of any one of claims 1 to 9, characterized in that: the gradient hydrogel soft driver is applied to biosensing, switching and intelligent robot arms.

Technical Field

The invention relates to the technical field of composite materials and high-molecular functional materials, in particular to a preparation method and application of a gradient hydrogel floppy drive.

Technical Field

The hydrogel is a three-dimensional network structure material formed by crosslinking hydrophilic polymer chains, and has wide application in life and production, such as sensors, tissue engineering, drug carriers, actuators and the like. However, with the popularization of hydrogels in these applications, the performance of conventional hydrogels has not been able to meet the requirements of these applications, so "smart" hydrogels have come into play. "smart" hydrogels have a heterogeneous structure that can respond anisotropically to changes in the environment, light, electricity, magnetism, pH, temperature, etc. For example, in a poly-N-isopropylacrylamide hydrogel with a non-uniform cross-linked structure, since the hydrogel exhibits hydrophilic swelling behavior in an environment below 32 ℃ and hydrophobic shrinkage behavior above 32 ℃, regions with different cross-linking densities microscopically undergo different swelling and shrinking behaviors, and macroscopically the hydrogel undergoes "smart" behavior such as bending or twisting with temperature change. Researchers have also investigated many "smart" hydrogel synthesis methods, such as microfluidic channels, molecular diffusion, bilayer structures, electric field induced gradient structures, etc., which aim to create a non-uniform structure of the hydrogel, thereby producing anisotropic "smart" behavior in the response of the environment.

Disclosure of Invention

The invention aims to provide a preparation method of a gradient hydrogel floppy drive, which solves the problems that the conventional hydrogel lacks 'intelligent' response performance and the interface defect of the hydrogel floppy drive with a double-layer structure is avoided.

The other purpose of the invention is to provide an application of the gradient hydrogel floppy driver, which is applied to biosensing, switches, arms of intelligent robots and the like.

The scheme adopted by the invention for realizing one of the purposes is as follows: a preparation method of a gradient hydrogel floppy drive comprises the steps of uniformly mixing a certain amount of negatively charged sea squirt cellulose nanocrystals, N-isopropylacrylamide, an auxiliary agent and water at a certain temperature to obtain a mixed solution; and inducing the mixed solution by a direct current electric field, and then preparing the gradient hydrogel soft driver by in-situ thermal initiation polymerization.

The hydrogel soft driver disclosed by the invention takes N-isopropylacrylamide (NIPAM) as a matrix and ascidian cellulose nanocrystals (TCNCs) as nanofillers, and under the action of an auxiliary agent, the ascidian cellulose nanocrystals are induced by a direct-current electric field to form gradient concentration, and then the gradient hydrogel is formed by in-situ thermal initiation.

Preferably, the concentration of the N-isopropamide in the mixed solution is 11.3 wt%, and the content of the ecteinascidin cellulose nanocrystals is 1 wt% to 5 wt% of the content of the N-isopropamide.

Preferably, the auxiliary agent comprises potassium persulfate (KPS), N, N-methylene-Bisacrylamide (BIS) and Tetramethylethylenediamine (TEMED), the content of the potassium persulfate (KPS) accounts for 0.96 wt% of the content of the N-isopropanolamide, the content of the N, N-methylene-bisacrylamide accounts for 0.33 wt% of the content of the N-isopropanolamide, and the content of the tetramethylethylenediamine accounts for 0.53% ml/g of the content of the N-isopropanolamide.

In the invention, N, N-methylene bisacrylamide is used as chemical crosslinking, tetramethylethylenediamine is used as an accelerator, and potassium persulfate is used as an initiator.

Preferably, the negatively charged sea squirt cellulose nanocrystals, the N-isopropylacrylamide and the auxiliary agent are mixed at a certain temperature and then induced by a direct current electric field at 0-4 ℃.

Preferably, the strength of the direct current electric field is 0.5-2V/mm.

Preferably, the time for inducing the direct current electric field is 15-60 min.

The temperature-sensitive bending performance of the hydrogel is controlled by controlling the concentration of the sea squirt cellulose nanocrystals, the strength of the induced direct current electric field and the induction time.

Preferably, the temperature of the in situ thermally initiated polymerization reaction is 18 to 25 ℃.

Preferably, the method further comprises the step of immersing the product into water at room temperature until the swelling equilibrium is reached after the in-situ thermal-initiated polymerization reaction is completed to obtain the gradient hydrogel floppy driver.

Preferably, the gradient hydrogel soft driver has the equilibrium swelling ratio of 34.5-40.6 g/g, the bending angle of-180 DEG in water at 40 ℃, the bending rate of 0-5.4 DEG/s in water at 40 ℃ and the recovery rate of 0-1.5 DEG/s in water at 25 ℃.

The second scheme adopted by the invention for achieving the purpose is as follows: the gradient hydrogel soft driver is applied to biosensing, switching and intelligent robot arms.

The invention has the following advantages and beneficial effects: the invention aims to solve the problems that the conventional hydrogel lacks intelligent response performance and the double-layer hydrogel floppy drive generates interface defects.

The preparation method is compounded by ecthyma cellulose nanocrystals and poly-N-isopropylacrylamide. Hydrolyzing sea squirt cellulose by using sulfuric acid to obtain sea squirt cellulose nanocrystals with negative electricity, then placing the sea squirt cellulose nanocrystals into a direct current electric field, enabling the sea squirt cellulose nanocrystals to move due to the electric field force to form gradient concentration, and finally initiating polymerization in situ to form the hydrogel soft driver with a gradient cross-linking structure. The hydrogel controls the cross-linking distribution of the hydrogel soft driver by controlling the strength of an electric field, the induction time of the electric field and the concentration of the sea squirt cellulose nanocrystals, thereby controlling the temperature-sensitive bending performance of the hydrogel, and being applicable to soft mechanical arms and the like. The hydrogel driver prepared by the scheme of the invention has controllable temperature-sensitive bending rate and fatigue resistance, is simple and easy to operate, and widens the application range of renewable resources of ascidian cellulose.

The preparation method adopts direct current electric field electrophoresis to induce the sea squirt cellulose nanocrystals with negative charges to form gradient concentration (the content of a positive electrode area is high, the content of a negative electrode area is low), then the sea squirt cellulose nanocrystals and N-isopropylacrylamide are polymerized in situ to form gradient hydrogel, and the sea squirt cellulose nanocrystals can be used as a chemical cross-linking agent and a nano filler to control the cross-linking density distribution of the hydrogel. Since the sea squirt cellulose nanocrystals form a gradient concentration under the action of the direct current electric field, the crosslinking density of the hydrogel gradually decreases from the positive electrode to the negative electrode. The poly-N-isopropenylacrylamide chain has temperature-sensitive hydrophilic-hydrophobic transformation, hydrophobic shrinkage at the temperature of more than 32 ℃ and hydrophilic swelling below 32 ℃, and because the cross-linking densities at two sides of the hydrogel are different, the shrinkage and swelling processes are asynchronous, so that the hydrogel has temperature-sensitive bending performance.

the preparation method of the invention takes natural sea squirt cellulose as raw material, and the sea squirt cellulose is recyclable: the method is simple and easy to implement by direct current electric field induction and then one-step thermal initiation; the crosslinking density of the hydrogel is changed step by step, so that interface defects are avoided; the temperature-sensitive bending performance of the hydrogel is controlled by controlling the content of the sea squirt cellulose nanocrystals and the strength and induction time of a direct current electric field.

The gradient hydrogel soft driver prepared by the method can be applied to biosensing, switches, arms of intelligent robots and the like.

Drawings

FIG. 1 is a definition of the bend angle of the present invention;

FIG. 2 is a graph showing the effect of different induction times on the bending performance of a hydrogel floppy drive according to the present invention;

FIG. 3 is a graph showing the effect of different electric field strengths on the bending performance of a hydrogel floppy drive according to the present invention;

FIG. 4 is a graph of the effect of different ascidian cellulose nanocrystal concentrations on hydrogel floppy drive bending performance in accordance with the present invention;

FIG. 5 is a cycle of bending and recovery of a hydrogel floppy drive according to the present invention;

FIG. 6 shows the grasping and releasing of a weight by the hydrogel of the present invention.

Detailed Description

the following examples are provided to further illustrate the present invention for better understanding, but the present invention is not limited to the following examples.