阅读说明：本技术 一种抗冻水凝胶及其制备方法与应用 (Anti-freezing hydrogel and preparation method and application thereof ) 是由 王小慧 葛文娇 孙润仓 于 2019-10-25 设计创作，主要内容包括：本发明属于水凝胶技术领域,具体涉及一种抗冻水凝胶及其制备方法与应用。该抗冻水凝胶包括交联聚合物、水、纳米纤维和锂盐。首先将锂盐和交联聚合物单体溶解在纳米纤维悬浮液中,然后在冰浴条件下,将引发剂、交联剂、助剂与纳米纤维/交联聚合物单体/锂盐分散液混合均匀,进行自由基聚合反应即得。该抗冻水凝胶利用了纳米纤维和聚丙烯酰胺网络之间的协同作用改善了力学性能,通过直接添加氯化锂的方式,使锂离子稳定存在于凝胶网络中,赋予水凝胶低温下抗冻的特性,在-80℃环境下可以任意拉伸、压缩。此外,可根据需求灵活调整氯化锂的加入量,制备不同相转变温度的抗冻水凝胶。该水凝胶的制备工艺简单,条件温和,便于实现大规模生产制备。(The invention belongs to the technical field of hydrogel, and particularly relates to anti-freezing hydrogel and a preparation method and application thereof. The antifreeze hydrogel comprises a cross-linked polymer, water, nanofibers and a lithium salt. Firstly, dissolving lithium salt and a cross-linked polymer monomer in a nanofiber suspension, then uniformly mixing an initiator, a cross-linking agent and an auxiliary agent with the nanofiber/cross-linked polymer monomer/lithium salt dispersion liquid under the ice bath condition, and carrying out free radical polymerization reaction to obtain the lithium salt/cross-linked polymer nanofiber/lithium salt dispersion liquid. The antifreeze hydrogel utilizes the synergistic effect between the nano-fiber and the polyacrylamide network to improve the mechanical property, enables lithium ions to stably exist in the gel network by directly adding lithium chloride, endows the hydrogel with the characteristic of freezing resistance at low temperature, and can be arbitrarily stretched and compressed at the temperature of-80 ℃. In addition, the addition amount of lithium chloride can be flexibly adjusted according to requirements, and the anti-freezing hydrogel with different phase transition temperatures can be prepared. The hydrogel is simple in preparation process, mild in condition and convenient for realizing large-scale production and preparation.)

1. A freeze resistant hydrogel characterized by: including a cross-linked polymer, water, nanofibers, and a lithium salt.

2. The antifreeze hydrogel of claim 1, wherein: the cross-linked polymer is formed by polymerizing acrylamide monomers.

3. The antifreeze hydrogel of claim 1, wherein: the nano-fiber is one or more than two of cellulose nano-fiber, cellulose nano-whisker, bacterial cellulose, chitin nano-whisker, sodium alginate nano-fiber or starch nano-whisker.

4. The antifreeze hydrogel of claim 1, wherein: the lithium salt is lithium chloride.

5. The antifreeze hydrogel of claim 1, wherein:

in the antifreeze hydrogel, the mass ratio of lithium salt to water is 0.1: 1-0.5: 1;

in the antifreeze hydrogel, the mass ratio of the cross-linked polymer to water is 0.2: 1-0.5: 1;

in the anti-freezing hydrogel, the mass ratio of the nano fibers to water is 0.01: 1-0.1: 1.

6. A method for preparing a freeze resistant hydrogel according to claims 1 to 5, comprising the steps of:

(1) dissolving lithium salt and a cross-linked polymer monomer in the nanofiber suspension, and uniformly stirring to obtain a nanofiber/cross-linked polymer monomer/lithium salt dispersion solution;

(2) and (2) under the ice bath condition, uniformly mixing an initiator, a cross-linking agent and an auxiliary agent with the nanofiber/cross-linked polymer monomer/lithium salt dispersion liquid, and carrying out free radical polymerization reaction to obtain the antifreeze hydrogel electrolyte.

7. Method for the preparation of a freeze-resistant hydrogel according to claim 6, characterized in that:

the initiator is ammonium persulfate, potassium persulfate, benzoyl oxide, tert-butyl hydroperoxide, benzoin ethyl ether or a photoinitiator 2959;

the cross-linking agent is N, N-methylene bisacrylamide, ethylene glycol diacrylate, ethylene glycol dimethacrylate or divinylbenzene.

8. Method for the preparation of a freeze-resistant hydrogel according to claim 6, characterized in that: the auxiliary agent is N, N, N ', N' -tetramethyl ethylenediamine, tetramethyl propylenediamine or dimethylethanolamine.

9. Method for the preparation of a freeze-resistant hydrogel according to claim 6, characterized in that: the mass ratio of the initiator, the cross-linking agent, the auxiliary agent and the cross-linked polymer monomer is (0.01-0.02): (0.0001-0.002): (0.001-0.01): 1.

10. Use of a freeze resistant hydrogel according to claims 1 to 5, characterized in that: the antifreeze hydrogel is used as an electrolyte in a supercapacitor.

Technical Field

The invention belongs to the technical field of hydrogel, and particularly relates to anti-freezing hydrogel and a preparation method and application thereof.

Background

Hydrogels are a class of high molecular polymers containing large amounts of water and having a three-dimensional network structure. Due to its special characteristics of softness and humidity, it has been widely used in the fields of electronic skin, flexible electronic devices, drivers, and biomedical applications. However, the conventional hydrogel is easy to freeze below zero degree, and the mechanical properties are reduced, which severely limits the practical application of the hydrogel in low temperature environment. In recent years, it has been studied to obtain an organic hydrogel having improved freezing resistance by mixing an organic liquid such as ethylene glycol or glycerin into a hydrogel system. However, the toxicity of the organic solvent may cause environmental pollution and harm human health. In addition, the participation of organic solvents tends to reduce the water content of the system, thereby failing to meet the application requirements of hydrogels in specific fields. In addition, it has been reported that the freezing point of the hydrogel is lowered by immersing the hydrogel in an inorganic salt solution. However, the dipping time of the method is generally up to several days, and the preparation period of the hydrogel is greatly prolonged. Therefore, designing a hydrogel of a pure water system with simple preparation process and freezing resistance and keeping excellent mechanical properties at low temperature is still a challenge to be solved.

Disclosure of Invention

In order to remedy the disadvantages and shortcomings of the prior art, it is a primary object of the present invention to provide a freeze-resistant hydrogel.

Another object of the present invention is to provide a process for the preparation of the above-mentioned deicing hydrogels.

It is a further object of the present invention to provide the use of the above-mentioned deicing hydrogels.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

an antifreeze hydrogel comprising a crosslinked polymer, water, nanofibers, and a lithium salt.

Preferably, the crosslinked polymer is polymerized from acrylamide monomers.

Preferably, the nanofiber is one or more than two of cellulose nanofiber, cellulose nanowhisker, bacterial cellulose, chitin nanowhisker, sodium alginate nanofiber or starch nanowhisker.

Preferably, the lithium salt is lithium chloride.

Preferably, in the antifreeze hydrogel, the mass ratio of the lithium salt to the water is 0.1: 1-0.5: 1.

Preferably, in the antifreeze hydrogel, the mass ratio of the cross-linked polymer to the water is 0.2: 1-0.5: 1.

Preferably, in the antifreeze hydrogel, the mass ratio of the nano fibers to the water is 0.01: 1-0.1: 1.

The invention further provides a preparation method of the anti-freezing hydrogel, which comprises the following steps:

(1) dissolving lithium salt and a cross-linked polymer monomer in the nanofiber suspension, and uniformly stirring to obtain a nanofiber/cross-linked polymer monomer/lithium salt dispersion solution;

(2) and (2) under the ice bath condition, uniformly mixing an initiator, a cross-linking agent and an auxiliary agent with the nanofiber/cross-linked polymer monomer/lithium salt dispersion liquid, and carrying out free radical polymerization reaction to obtain the antifreeze hydrogel electrolyte.

Preferably, the initiator is ammonium persulfate, potassium persulfate, benzoyl oxide, tert-butyl hydroperoxide, benzoin ethyl ether or a photoinitiator 2959.

Preferably, the crosslinking agent is N, N-methylene bisacrylamide, ethylene glycol diacrylate, ethylene glycol dimethacrylate or divinylbenzene.

Preferably, the assistant is N, N, N ', N' -tetramethylethylenediamine, tetramethylpropylenediamine or dimethylethanolamine.

Preferably, the mass ratio of the initiator, the crosslinking agent, the auxiliary agent and the crosslinked polymer monomer is (0.01-0.02): (0.0001-0.002): (0.001-0.01): 1.

The invention further provides the use of the above-described antifreeze hydrogels as electrolytes in supercapacitors.

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

(1) the synergistic effect between the nano-fibers and the polyacrylamide network in the antifreeze hydrogel prepared by the invention improves the mechanical property of the hydrogel. And lithium ions are stably present in the gel network by means of direct addition of lithium chloride. The hydrogel is endowed with the characteristic of freezing resistance at low temperature by virtue of the characteristic of lithium chloride, so that the hydrogel still keeps the soft state of the hydrogel under the low-temperature condition, has high stretchability and compressibility, can be arbitrarily stretched and compressed at the temperature of-80 ℃, and still keeps the property of the hydrogel.

(2) In the preparation process, the addition of the lithium chloride can be flexibly adjusted according to requirements, and the anti-freezing hydrogel with different phase transition temperatures can be prepared. When the mass ratio of the lithium chloride to the water in the system is 0.1: 1-0.5: 1, the phase transition temperature decreases with the increase of the mass ratio of the lithium chloride to the water in the system.

(3) The preparation method has the advantages of simple preparation process, mild conditions and convenience for realizing large-scale production and preparation.

Drawings

FIG. 1 shows the dynamic thermomechanical profile of the deicing hydrogel prepared in example 1.

FIG. 2 is a tensile stress-strain curve at 25 ℃ for the antifreeze hydrogel prepared in example 1.

FIG. 3 is a compressive stress-strain curve at 25 ℃ for the antifreeze hydrogel prepared in example 1.

FIG. 4 is a diagram of the stretching and compression of the antifreeze hydrogel prepared in example 1 at-80 ℃.

FIG. 5 is a dynamic thermomechanical profile of the freeze-resistant hydrogel prepared in example 2.

FIG. 6 is a tensile stress-strain curve at 25 ℃ for the antifreeze hydrogel prepared in example 2.

FIG. 7 is a compressive stress-strain curve at 25 ℃ for the antifreeze hydrogel prepared in example 2.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the embodiments of the present invention are not limited thereto. For process parameters not specifically noted, reference may be made to conventional techniques.