Preparation method of n-p type ionic thermoelectric hydrogel based on bi-crosslinked network structure

Abstract

The invention provides a preparation method of n-p type ionic thermoelectric hydrogel based on a bi-crosslinked network structure. The preparation method comprises the following steps: (1) dissolving a binary hydrogel substrate in water according to a certain proportion; (2) adding a cross-linking agent; (3) dropwise adding the stirred solution into a mold, and carrying out curing molding and drying at a certain temperature; and (4) soaking the cured hydrogel in an n-type ion solution and a p-type ion solution with a certain concentration respectively, and after a period of time, assembling the hydrogel to obtain the n-p type ion thermoelectric hydrogel based on the double-crosslinked network structure. Different from thermoelectric hydrogel which only has a network structure and only uses one thermoelectric type, the technical scheme designs the thermoelectric hydrogel initiated by n-p type ions based on a double-crosslinking network structure, so that more efficient and more stable energy conversion and utilization can be realized; and a new solution is provided for the fields of flexible electronic equipment, low-grade heat energy recovery and the like.

Description

Technical Field

[0001] The present invention belongs to the field of functional polymer materials, and particularly relates to a preparation method of an n-p type ionic thermoelectric hydrogel based on a double cross-linked network structure. Background Art

[0002] Thermoelectric materials have become a research hotspot in the energy field because they can directly convert thermal energy into electrical energy, and have important application potential especially in the fields of low-grade thermal energy recovery and power supply for flexible electronic devices.

[0003] Thermoelectric hydrogels combine the energy conversion ability of traditional thermoelectric materials with the flexibility, biocompatibility and ionic conductivity of hydrogels, becoming an ideal flexible thermoelectric material. The thermoelectric effect of ionic hydrogels is mainly based on ion migration and redox reactions. However, ionic hydrogels of a single thermoelectric type have limited performance in terms of thermoelectric performance, stability and energy conversion efficiency, and it is difficult to meet the requirements of efficient energy recovery and long-term stable applications.

[0004] To break through the above limitations, the present technology proposes a preparation method of a thermoelectric hydrogel using two thermoelectric types. By integrating n-type ions (such as FeCl 2 / FeCl 3 ) and p-type ions (such as K 3 [Fe(CN) 6 / K 4 [Fe(CN) 6 ) into a single hydrogel system, and utilizing the synergistic effect of the two thermoelectric types, the thermoelectric performance and output power of the hydrogel are significantly improved. In addition, by adopting a dynamic cross-linked network and an ion thermal migration mechanism, the mechanical strength, self-healing ability and electrochemical stability of the hydrogel are further enhanced, thus meeting the actual requirements of flexible electronic devices and low-grade thermal energy recovery.

[0005] The present technology not only provides a new research idea for the development of new flexible thermoelectric materials, but also lays a foundation for realizing efficient and stable energy conversion devices. Summary of the Invention

[0006] The purpose of the present invention is to solve the deficiencies of the prior art, and provides a method for preparing a thermoelectric hydrogel with a simple preparation method, having a hydrogel cross-linked network, using a thermoelectric type triggered by two ions, and capable of assembling small thermoelectric devices.

[0007] To achieve the above invention purpose, the present invention adopts the following technical solutions:

[0008] A preparation method of an n-p type ionic thermoelectric hydrogel based on a double cross-linked network structure, comprising the following steps:

[0009] (1) Preparation of hydrogel prepolymer solution: Add a certain amount of binary hydrogel substrate to deionized water, and stir until the material dissolves under certain temperature and rotation speed conditions;

[0010] (2) Preparation of crosslinked hydrogel: After the solution is cooled to room temperature, add a crosslinking agent and stir until the material dissolves;

[0011] (3) Preparation of hydrogel prepolymer: Drop the stirred solution into a mold, place the mold in a forced-air oven for curing and thermal drying;

[0012] (4) Take out the cured hydrogel in step (3) and soak it in ionic solutions of certain concentrations respectively;

[0013] (5) Then assemble and connect in series the thermoelectric hydrogels obtained in step (4) using copper foil to obtain an n-p type thermoelectric hydrogel.

[0014] Furthermore, the hydrogel substrate of the present invention can be acrylamide, sodium alginate, sodium carboxymethyl cellulose, polyvinyl alcohol, polyacrylic acid, sodium acrylate, chitosan, gelatin, etc.

[0015] Furthermore, the crosslinking agent of the present invention is N’N’-methylenebisacrylamide and ammonium persulfate or potassium persulfate.

[0016] Furthermore, the ionic solution for soaking the n-type thermoelectric hydrogel obtained in the present invention is ferric chloride / ferrous chloride or sulfate / sulfite.

[0017] Furthermore, the ionic solution for soaking the p-type thermoelectric hydrogel obtained in the present invention is potassium ferricyanide / potassium ferrocyanide or triiodide / iodide ion pair.

[0018] Furthermore, the two types of thermoelectric hydrogels of the present invention are assembled using copper foil to obtain an n-p type thermoelectric hydrogel.

[0019] Advantages of the present invention:

[0020] The binary hydrogel substrate adopted in the present invention forms a three-dimensional double-crosslinked network structure under the action of a crosslinking agent, which enhances its mechanical properties while maintaining the original flexible flexibility of the hydrogel; the hydrogel prepolymer made using a customized mold can meet the assembly of various types of flexible thermoelectric devices; two different types of thermoelectric hydrogels are obtained by soaking with two different types of ions; the n-p type thermoelectric hydrogel that absorbs different types of ions in the present invention can significantly increase the electric power under the drive of temperature difference and can achieve large-scale production. Description of the drawings

[0021] Figure 1 It is the electron microscope structure diagram of the thermoelectric hydrogel prepolymer of the present invention;

[0022] Figure 2 The assembly principle of the n-p type thermoelectric hydrogel prepared in Example 4 of the present invention;

[0023] Figure 3 The small thermoelectric device of the n-p type thermoelectric hydrogel prepared in Example 4 of the present invention;

[0024] Figure 4 It is the power density of the reduced assembly of the n-p type thermoelectric hydrogel. Specific embodiments

[0025] Examples and comparative examples are listed to illustrate the present invention more specifically, but the present invention is not limited by these examples within the scope of its main idea.

[0026] Example 1

[0027] A preparation method of a thermoelectric hydrogel using two thermoelectric types, comprising the following steps:

[0028] (1). Prepare the hydrogel prepolymer solution: Add 0.5 - 1 g of polyvinyl alcohol (PVA) and 2.1 - 3.5 g of acrylamide to 10 - 30 mL of deionized water, and stir at 90 °C and 400 rpm for 1 h until the materials are dissolved;

[0029] (2). Prepare the crosslinked hydrogel: After the solution is cooled to room temperature, add 0.01 - 0.04 g of N’N-methylenebisacrylamide and 0.01 - 0.04 g of ammonium persulfate, and stir at 400 rpm for 10 min until the materials are dissolved;

[0030] (3). Prepare the hydrogel prepolymer: Drop the stirred solution into a 10*10*3 mm mold, place the mold in a forced-air oven, and perform thermal drying at 80 °C for 12 h;

[0031] (4). Take out the dried hydrogel prepolymer in step (3) and soak it in a 0.05 - 0.15 mol / L potassium ferricyanide / ferrous potassium cyanide solution to obtain a p-type thermoelectric hydrogel

[0032] (5). Take out the dried hydrogel prepolymer in step (3) and soak it in a 0.01 - 0.1 mol / L ferric chloride / ferrous chloride solution to obtain an n-type thermoelectric hydrogel

[0033] (6). Then assemble and connect in series the thermoelectric hydrogels obtained in steps (4) and (5) using copper foil to obtain an n-p type thermoelectric hydrogel.

[0034] Test Example 1

[0035] Characterize the surface structure of the thermoelectric hydrogel obtained in Example 1 above using a scanning electron microscope, as shown inFigure 1 ; and use a digital source table to apply a temperature gradient to the assembled thermoelectric hydrogel for testing, as shown in Figure 4 .

[0036] As Figure 1 can be seen, the surface of the hydrogel prepolymer is a porous structure, which indicates that the hydrogel can fully absorb ions during soaking and provide a large number of channels for ions during thermal stimulation. The present invention uses polyvinyl alcohol to fill acrylamide hydrogel, which has a filled three-dimensional network structure and has a certain anti-mechanical strength.

[0037] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

[0038] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an np-type ionic thermoelectric hydrogel based on a double cross-linked network structure, characterized in that: The steps include: a. Preparation of hydrogel precursor solution: adding a certain amount of binary hydrogel substrate into deionized water, and stirring at a certain temperature and rotation speed until the material is dissolved; b. Preparation of cross-linked hydrogel: After cooling the above solution to room temperature, add a cross-linking agent and stir at a certain rotation speed until the material is dissolved; c. Preparation of hydrogel precursor: dripping the stirred solution into a customized mold, placing the mold in a blast oven, and curing and drying under certain temperature conditions; d. taking out the hydrogel precursor dried in step c and soaking it in different ion solutions to obtain n-type or p-type thermoelectric hydrogels respectively; e. The two thermoelectric types of thermoelectric hydrogels in step d were assembled into np-type thermoelectric hydrogels.

2. The method for preparing a thermoelectric hydrogel using two thermoelectric types according to claim 1, characterized in that: The hydrogel substrate described in step a can be acrylamide, sodium alginate, sodium carboxymethyl cellulose, polyvinyl alcohol, polyacrylic acid, sodium acrylate, chitosan, gelatin, etc.

3. The method for preparing a thermoelectric hydrogel using two thermoelectric types according to claim 1, characterized in that: The cross-linking agent in step b is N'N'-methylenebisacrylamide and ammonium persulfate or potassium persulfate.

4. The method for preparing a thermoelectric hydrogel using two thermoelectric types according to claim 1, characterized in that: The ion solution in which the n-type thermoelectric hydrogel is immersed in step d is ferric chloride / ferrous chloride or sulfate / sulfite.

5. The method for preparing a thermoelectric hydrogel using two thermoelectric types according to claim 1, characterized in that: The ion solution in which the p-type thermoelectric hydrogel is immersed in step d is potassium ferrocyanide / potassium ferrocyanide or triiodide / iodide ion pairs.

6. A method for preparing a thermoelectric hydrogel using two thermoelectric types according to any one of claims 1 to 5, characterized in that: The thermoelectric hydrogel obtained in step d is assembled and connected in series using copper foil to obtain an np-type thermoelectric hydrogel.

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