Temperature-regulating phase-change fabric and preparation method thereof

Abstract

The invention discloses a temperature-regulating phase-change fabric and a preparation method thereof. Epichlorohydrin is used as a cross-linking agent, beta-cyclodextrin molecules are grafted to carboxymethyl cellulose under the catalysis of sodium hydroxide, and the carboxymethyl cellulose-beta-cyclodextrin graft polymer is prepared. Then, polyoxyethylene and boron nitride nanosheets are filled into the graft polymer network, and a spinning auxiliary agent polyvinyl alcohol aqueous solution is added to obtain a phase change precursor solution; and filling the precursor solution into an injector, spinning under a certain condition, and finally drying in a drying oven to obtain the temperature-regulating phase-change fabric. The temperature-adjusting phase-change fabric prepared by the invention is a white fabric, has super-flexibility and shape stability, and has good application significance in the aspect of human body thermal therapy.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal energy storage and utilization, and particularly to a preparation method of a functional phase change fabric for regulating human body temperature. Background Art

[0002] In current human society, with the improvement of living standards, hyperthermia technology has become increasingly important in medicine. Current hyperthermia methods mainly rely on electrothermal heating and infrared lamp hyperthermia. However, continuous external heat input can cause the temperature to rise above the temperature range required for hyperthermia, which can affect the hyperthermia effect and easily cause burns. Therefore, it is very important to develop functional materials for hyperthermia with approximate constant temperature. Phase change materials (PCMs) are functional materials that can undergo phase changes at approximately constant temperatures and have extremely high energy storage densities. In addition, they also have excellent thermal stability, biocompatibility, and excellent thermal cycling ability, and have broad application prospects in the field of human hyperthermia. However, solid-liquid organic PCMs have extremely strong rigidity in the solid state, and there are also problems of liquid leakage during their phase change processes. To overcome these difficulties, it is necessary to develop new composite materials with shape stability and flexibility.

[0003] Patent CN115807276A prepared a composite material of nano tungsten trioxide and polystyrene-b-poly(ethylene-butene)-b-polystyrene block copolymer by coaxial wet spinning. Using it as the shell and paraffin wax as the core phase change material, a phase change fiber membrane was prepared to respond to and buffer external environmental temperature changes by absorbing / releasing thermal energy. However, the low yield of preparing the fiber membrane by coaxial wet spinning limits its large-scale application. Patent CN114481358B used an organic phase change material emulsion as the inner phase spinning solution and a polyacrylonitrile spinning solution as the outer phase spinning solution for coaxial wet spinning, and then obtained phase change temperature-regulating fibers after soaking in water and freeze-drying. However, the solvents N,N-dimethylformamide and dimethyl sulfoxide used in the spinning solution are harmful to the human body or the environment. Patent CN104831388B encapsulated the phase change material paraffin wax into honeycomb-shaped silica to obtain phase change microparticles, and then combined them with a spinning emulsion and spun them into shape through a coagulation bath to prepare phase change temperature-regulating fibers. However, the melting enthalpy value of this fiber is only 5.8 J / g, which limits its application. Summary of the Invention

[0004] The present invention develops a preparation strategy for electrospinning. Using epichlorohydrin as a crosslinking agent, β-cyclodextrin molecules are grafted onto carboxymethyl cellulose under the catalysis of sodium hydroxide to obtain a carboxymethyl cellulose-β-cyclodextrin grafted polymer. Subsequently, the phase change material polyethylene oxide and boron nitride nanosheets are filled into the grafted polymer network, and an aqueous solution of polyvinyl alcohol as a spinning aid is added to obtain a phase change precursor solution. Finally, the precursor solution is loaded into a syringe, electrospun and dried to obtain a temperature-regulating phase change fabric with remarkable self-supporting, super-flexible and shape-stable properties. The obtained phase change fabric exhibits a relatively high latent heat (about 50 J g -1 ), and remarkable shape stability. In addition, due to its exothermic range within 45 - 65 °C, the phase change fabric has important applications in the field of human thermotherapy.

[0005] The method for synthesizing a temperature-regulating phase change fabric according to the present invention includes the following steps:

[0006] (1) Preparation of carboxymethyl cellulose-β-cyclodextrin polymer

[0007] Add 5 - 7 parts of carboxymethyl cellulose and 1 - 3 parts of β-cyclodextrin to 100 parts of an aqueous sodium hydroxide solution, stir and dissolve at a certain temperature, then add 1 - 3 parts of epichlorohydrin for crosslinking reaction. After the reaction is completed, use 1 - 2 mol / L hydrochloric acid to adjust the pH of the solution to 5 - 8 to obtain an aqueous polymer solution;

[0008] (2) Preparation of phase change precursor solution

[0009] Add 12 - 14 parts of polyethylene oxide and 1 - 3 parts of boron nitride nanosheets to the aqueous polymer solution obtained in (1). After the polyethylene oxide is completely dissolved, add 15 - 20 parts of an aqueous polyvinyl alcohol solution, stir evenly and let stand to obtain an electrospinning solution;

[0010] (3) Preparation of temperature-regulating phase change fabric by electrospinning

[0011] Load the electrospinning solution obtained in (2) into a syringe, use an electrospinning device for spinning. After spinning, place the receiving plate in an oven for drying to obtain a phase change fabric.

[0012] Furthermore, in the step (1), the mass fraction of sodium hydroxide in the aqueous sodium hydroxide solution is 4 - 6 wt.%. Sodium hydroxide is a catalyst for the reaction, which can activate the hydroxyl groups on the β-cyclodextrin molecules, attack the epoxy groups of epichlorohydrin, and then react with the primary hydroxyl groups of carboxymethyl cellulose to graft the β-cyclodextrin molecules onto carboxymethyl cellulose. The inner hydrophobic and outer hydrophilic cavity structure of β-cyclodextrin can increase the loading amount of carboxymethyl cellulose for boron nitride nanosheets and polyethylene oxide.

[0013] Further, in the step (1), the reaction temperature is 45 - 55 °C, and the reaction time is 5 - 6 h. Increasing the reaction temperature can accelerate the reaction rate and thus increase the grafting rate of β-cyclodextrin. However, when the temperature is higher than 55 °C, side reactions such as hydrolysis and self-polymerization of epichlorohydrin increase, resulting in a decrease in the content of epichlorohydrin, which is not conducive to the grafting of β-cyclodextrin.

[0014] Further, in the step (2), the number-average molecular weight range of polyethylene oxide is 50 - 5 million, preferably 2 - 4 million. As a phase change material, polyethylene oxide undergoes solid-liquid phase transition and absorbs heat when the external environmental temperature is higher than the melting temperature, maintaining its own temperature and endowing the fabric with temperature regulation function.

[0015] Further, in the step (2), the sheet diameter of boron nitride nanosheets is 0.2 - 2 μm. The porous structure in boron nitride nanosheets can adsorb liquid polyethylene oxide, enabling it to remain in the system after solid-liquid phase transition without leaking into the environment.

[0016] Further, in the step (2), the degree of alcoholysis of polyvinyl alcohol is 87 - 89%, the degree of polymerization is 2000 ± 50, and the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 10 - 15 wt.%. Polyvinyl alcohol has good solubility, plasticity, and degradability, and is used to improve the spinnability of carboxymethyl cellulose. The addition of polyvinyl alcohol improves the uniformity and continuity of the fibers, making the phase change fabric smoother and softer.

[0017] Further, in the step (3), the distance between the needle tip and the receiving plate of the electrospinning device is 14 - 16 cm, the solution flow rate is 1 - 2 ml / h, the positive pressure is 18 - 20 KV, and the negative pressure is 1 - 2 KV. The process conditions of electrospinning have an important impact on the properties of the phase change fibers, and the phase change fabric obtained under these conditions has better effects.

[0018] Further, in the step (3), the oven drying temperature is 60 - 90 °C, and the drying time is 12 - 36 h. The higher the drying temperature, the faster the drying speed. However, if the temperature is too high, the structure of the polymer fibers will be damaged, thus affecting the hand feeling and quality of the phase change fabric. The drying temperature in the range of 60 - 90 °C is appropriate.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention prepares a temperature-regulating phase change fabric through steps such as polymer grafting reaction, phase change working medium filling, electrospinning, and drying. The solvent used is water, and the process conditions require less, which is conducive to large-scale production.

[0021] (2) The precursor solution is a water-soluble polymer solution, and the materials used in the preparation are non-toxic, harmless, and environmentally friendly. The prepared temperature-regulating phase-change fabric has good flexibility and high tensile strength, and can be applied to a variety of scenarios.

[0022] (3) The prepared temperature-regulating phase-change fabric has good adhesion, no liquid leakage after phase change, and a moderate phase-change temperature (45 - 65 °C) and high heat storage density, showing broad application prospects in human thermotherapy. Description of the Drawings

[0023] Figure 1 : Differential scanning calorimetry curve of the temperature-regulating phase-change fabric in Example 1.

[0024] Figure 2 : Tensile strength curve of the temperature-regulating phase-change fabric in Example 1. Detailed Description of the Invention

[0025] Example 1

[0026] (1) Take 100 parts of a 5 wt.% sodium hydroxide aqueous solution, add 6 parts of carboxymethyl cellulose and 2 parts of β-cyclodextrin, and heat to 50 °C with stirring until dissolved. Then add 2 parts of epichlorohydrin and react at 50 °C for 6 h. After the reaction, adjust the pH of the solution to 7 with 2 mol / L hydrochloric acid to obtain an aqueous polymer solution.

[0027] (2) Add 12 parts of polyethylene oxide with a molecular weight of 4 million and 2 parts of boron nitride nanosheets with a sheet diameter of 0.2 μm to the aqueous polymer solution obtained in (1). Stir until the polyethylene oxide is completely dissolved, then add 16 parts of a 14 wt.% polyvinyl alcohol aqueous solution, stir for 2 h, and then let it stand to obtain an electrospinning solution.

[0028] (3) Load the electrospinning solution obtained in (2) into a syringe, and use an electrospinning device for spinning. The distance between the tip of the electrospinning device and the receiving plate is 15 cm, the solution flow rate is 1 ml / h, the positive pressure is 18 KV, and the negative pressure is 2 KV. After spinning, place the receiving plate in an oven and dry at 80 °C for 20 h to obtain a phase-change fabric.

[0029] The prepared temperature-regulating phase-change fabric has a white appearance and is soft and foldable. Its melting temperature is 62.4 °C, and the phase-change enthalpy value is 50.1 J g -1 , and the differential scanning calorimetry curve is as Figure 1 shown. Its breaking tensile strength is 803 MPa, the elongation at break is 50%, and the breaking tensile curve is as Figure 2 shown.

[0030] Example 2

[0031] (1) Take 100 parts of a sodium hydroxide aqueous solution with a mass fraction of 5 wt.%, add 7 parts of carboxymethyl cellulose and 3 parts of β-cyclodextrin, and then heat to 50 °C and stir to dissolve. Then add 3 parts of epichlorohydrin and react at 50 °C for 6 h. After the reaction, use 2 mol / L hydrochloric acid to adjust the pH of the solution to 7 to obtain an aqueous polymer solution.

[0032] (2) Add 14 parts of polyethylene oxide with a molecular weight of 4 million and 3 parts of boron nitride nanosheets with a sheet diameter of 0.2 μm to the aqueous polymer solution obtained in (1). Stir until the polyethylene oxide is completely dissolved, then add 20 parts of a 15 wt.% aqueous solution of polyvinyl alcohol, stir for 2 h, and then let it stand to obtain an electrospinning solution.

[0033] (3) Load the electrospinning solution obtained in (2) into a syringe and use an electrospinning device for spinning. The distance between the tip of the electrospinning device and the receiving plate is 15 cm, the solution flow rate is 1 ml / h, the positive pressure is 18 KV, and the negative pressure is 2 KV. After spinning, place the receiving plate in an oven and dry at 80 °C for 20 h to obtain a phase change fabric.

[0034] Example 3

[0035] (1) Take 100 parts of a sodium hydroxide aqueous solution with a mass fraction of 5 wt.%, add 5 parts of carboxymethyl cellulose and 1 part of β-cyclodextrin, and then heat to 50 °C and stir to dissolve. Then add 1 part of epichlorohydrin and react at 50 °C for 6 h. After the reaction, use 2 mol / L hydrochloric acid to adjust the pH of the solution to 7 to obtain an aqueous polymer solution.

[0036] (2) Add 12 parts of polyethylene oxide with a molecular weight of 4 million and 1 part of boron nitride nanosheets with a sheet diameter of 0.2 μm to the aqueous polymer solution obtained in (1). Stir until the polyethylene oxide is completely dissolved, then add 15 parts of a 10 wt.% aqueous solution of polyvinyl alcohol, stir for 2 h, and then let it stand to obtain an electrospinning solution.

[0037] (3) Load the electrospinning solution obtained in (2) into a syringe and use an electrospinning device for spinning. The distance between the tip of the electrospinning device and the receiving plate is 15 cm, the solution flow rate is 1 ml / h, the positive pressure is 18 KV, and the negative pressure is 2 KV. After spinning, place the receiving plate in an oven and dry at 80 °C for 20 h to obtain a phase change fabric.

[0038] Example 4

[0039] (1) Take 100 parts of a sodium hydroxide aqueous solution with a mass fraction of 4 wt.%, add 6 parts of carboxymethyl cellulose and 2 parts of β-cyclodextrin, and then heat to 55 °C and stir to dissolve. Then add 2 parts of epichlorohydrin and react at 55 °C for 6 h. After the reaction, use 2 mol / L hydrochloric acid to adjust the pH of the solution to 6 to obtain an aqueous polymer solution.

[0040] (2) Add 14 parts of polyethylene oxide with a molecular weight of 2 million and 2 parts of boron nitride nanosheets with a sheet diameter of 0.8 μm to the polymer aqueous solution obtained in (1). After stirring until the polyethylene oxide is completely dissolved, add 20 parts of a 10 wt.% aqueous solution of polyvinyl alcohol, stir for 2 h, and then let it stand to obtain an electrospinning solution.

[0041] (3) Load the electrospinning solution obtained in (2) into a syringe and use an electrospinning device for spinning. The distance between the tip of the electrospinning device and the receiving plate is 15 cm, the solution flow rate is 1 ml / h, the positive pressure is 18 KV, and the negative pressure is 2 KV. After spinning, place the receiving plate in an oven and dry it at 60 °C for 36 h to obtain a phase change fabric.

[0042] Example 5

[0043] (1) Take 100 parts of a 6 wt.% aqueous solution of sodium hydroxide, add 6 parts of carboxymethyl cellulose and 2 parts of β-cyclodextrin, and heat to 45 °C with stirring for dissolution. Then add 2 parts of epichlorohydrin and react at 45 °C for 6 h. After the reaction, adjust the pH of the solution to 8 with 2 mol / L hydrochloric acid to obtain a polymer aqueous solution.

[0044] (2) Add 14 parts of polyethylene oxide with a molecular weight of 5 million and 2 parts of boron nitride nanosheets with a sheet diameter of 2.0 μm to the polymer aqueous solution obtained in (1). After stirring until the polyethylene oxide is completely dissolved, add 15 parts of a 15 wt.% aqueous solution of polyvinyl alcohol, stir for 2 h, and then let it stand to obtain an electrospinning solution.

[0045] (3) Load the electrospinning solution obtained in (2) into a syringe and use an electrospinning device for spinning. The distance between the tip of the electrospinning device and the receiving plate is 15 cm, the solution flow rate is 1 ml / h, the positive pressure is 18 KV, and the negative pressure is 2 KV. After spinning, place the receiving plate in an oven and dry it at 90 °C for 12 h to obtain a phase change fabric.

[0046] Comparative Example 1

[0047] (1) Take 100 parts of a 5 wt.% aqueous solution of sodium hydroxide, add 6 parts of carboxymethyl cellulose, and heat to 50 °C with stirring for dissolution. Then adjust the pH of the solution to 7 with 2 mol / L hydrochloric acid to obtain a polymer aqueous solution.

[0048] (2) Add 12 parts of polyethylene oxide with a molecular weight of 4 million and 2 parts of boron nitride nanosheets with a sheet diameter of 0.2 μm to the polymer aqueous solution obtained in (1). After stirring until the polyethylene oxide is completely dissolved, add 16 parts of a 14 wt.% aqueous solution of polyvinyl alcohol, stir for 2 h, and then let it stand to obtain an electrospinning solution.

[0049] (3) Load the electrospinning solution obtained in (2) into a syringe and perform electrospinning using an electrospinning device. The distance between the tip of the electrospinning device and the receiving plate is 15 cm, the solution flow rate is 1 ml / h, the positive pressure is 18 KV, and the negative pressure is 2 KV. After electrospinning, place the receiving plate in an oven and dry it at 80 °C for 20 h to obtain a phase change fabric.

[0050] Comparative Example 2

[0051] (1) Take 100 parts of an aqueous sodium hydroxide solution with a mass fraction of 5 wt.%, add 6 parts of carboxymethyl cellulose and 2 parts of β-cyclodextrin, and heat to 50 °C with stirring to dissolve. Then add 2 parts of epichlorohydrin and react at 50 °C for 6 h. After the reaction, adjust the pH of the solution to 7 using 2 mol / L hydrochloric acid to obtain an aqueous polymer solution.

[0052] (2) Add 12 parts of polyethylene oxide with a molecular weight of 4 million and 2 parts of boron nitride nanosheets with a sheet diameter of 0.2 μm to the aqueous polymer solution obtained in (1), stir until the polyethylene oxide is completely dissolved, and then let it stand to obtain an electrospinning solution.

[0053] (3) Load the electrospinning solution obtained in (2) into a syringe and perform electrospinning using an electrospinning device. The distance between the tip of the electrospinning device and the receiving plate is 15 cm, the solution flow rate is 1 ml / h, the positive pressure is 18 KV, and the negative pressure is 2 KV. After electrospinning, place the receiving plate in an oven and dry it at 80 °C for 20 h to obtain a phase change fabric.

[0054] Testing Method

[0055] Phase change performance: The phase change performance is measured by differential scanning calorimetry (DSC). In this experiment, Discovery DSC (TA Instruments, USA) is used, the heating rate is 10 °C / min, and the nitrogen gas flow rate is 20 ml / min. Among them, the phase change temperature is obtained by extrapolating the DSC curve of the phase change part of the sample, and the phase change enthalpy value is obtained by integrating the heat flow during the phase change process.

[0056] Tensile performance: The tensile performance is tested using a domestic universal tensile testing machine, the gauge length is 1.5 cm, and the tensile speed is 2.0 cm / min.

[0057] Table 1: Performance table of the temperature-regulating phase change fabric in the examples

[0058]

[0059] By comparing Example 1 with Comparative Example 1, it can be seen that using β-cyclodextrin grafted carboxymethyl cellulose can increase the loading amount of the polymer on the phase change material polyethylene oxide, thereby increasing the phase change enthalpy value of the temperature-regulating fabric. At the same time, the tensile performance of the temperature-regulating phase change fabric after grafting is also significantly improved.

[0060] By comparing Example 1 with Comparative Example 2, it can be seen that after adding the polyvinyl alcohol aqueous solution, the breaking tensile strength and elongation ratio of the temperature-regulating phase-change fabric increase, and the tensile properties are significantly improved.

Claims

1. Preparation method of temperature-regulating phase-change fabric, comprising the following steps: (1) Preparation of carboxymethyl cellulose-β-cyclodextrin polymer Add 5-7 parts of carboxymethyl cellulose and 1-3 parts of β-cyclodextrin to 100 parts of sodium hydroxide aqueous solution, stir and dissolve at a certain temperature, then add 1-3 parts of epichlorohydrin for cross-linking reaction. After the reaction, use 1-2 mol / L hydrochloric acid to adjust the pH of the solution to 5-8 to obtain an aqueous polymer solution; (2) Preparation of phase-change precursor solution Add 12-14 parts of polyethylene oxide and 1-3 parts of boron nitride nanosheets to the aqueous polymer solution obtained in (1). After the polyethylene oxide is completely dissolved, add 15-20 parts of aqueous polyvinyl alcohol solution, stir evenly and let stand to obtain an electrospinning solution; (3) Preparation of temperature-regulating phase-change fabric by electrospinning Load the electrospinning solution obtained in (2) into a syringe, use an electrospinning device for spinning. After spinning, place the receiving plate in an oven for drying to obtain a phase-change fabric.

2. The preparation method according to claim 1, characterized in that, in the step (1), the mass fraction of sodium hydroxide in the sodium hydroxide aqueous solution is 4-6 wt.%.

3. The preparation method according to claim 1, characterized in that, in the step (1), the reaction temperature is 45-55 °C.

4. The preparation method according to claim 1, characterized in that, in the step (2), the number-average molecular weight range of polyethylene oxide is 50-5 million, preferably 2-4 million.

5. The preparation method according to claim 1, characterized in that, in the step (2), the sheet diameter of the boron nitride nanosheets is 0.2-2 μm.

6. The preparation method according to claim 1, characterized in that, in the step (2), the mass fraction of polyvinyl alcohol in the aqueous polyvinyl alcohol solution is 10-15 wt.%.

7. The preparation method according to claim 1, characterized in that, in the step (3), the distance between the needle tip of the electrospinning device and the receiving plate is 14-16 cm, the solution flow rate is 1-2 ml / h, the positive pressure is 18-20 KV, and the negative pressure is 1-2 KV.

8. The preparation method according to claim 1, characterized in that in the step (3), the drying temperature is 60-90 °C and the drying time is 12-36 h.

9. Temperature-regulating phase-change fabric prepared by the preparation method according to any one of claims 1-8.

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