溴化锌/纤维素协同增强的抗冻导电聚乙烯醇水凝胶及其柔性传感应用

Construction of zinc bromide/cellulose-reinforced high-performance antifreezing conductive poly(vinyl alcohol) hydrogels for flexible sensing applications

摘要

【目的】水凝胶的机械柔韧性与低温环境适应性对其在柔性传感器中的应用至关重要。然而，现有的聚乙烯醇（PVA）水凝胶在低温下易冻结失效，且其力学性能、导电性和环境稳定性难以协同提升，限制了其在复杂形变和极端环境条件下的实际应用。为此，本研究旨在开发一种兼具抗冻、高导电与优异力学性能的复合水凝胶，以满足柔性电子器件在多变环境中的使用需求。【方法】本研究以竹溶解浆纤维素（BDP）为原料，采用溴化锌（ZnBr₂）溶剂体系实现纤维素溶解，并构建刚性导电的 BDP/Zn²⁺网络；进一步通过戊二醛（GA）化学交联与一次冻融相结合的方法，将上述网络引入聚乙烯醇（PVA/GA）柔性网络中，以制备具有优异综合性能的复合水凝胶（BZPG）。【结果】（1）BDP 与 Zn²⁺的协同作用显著提升了水凝胶的力学性能：当 BDP/ZnBr₂ 溶液与 PVA 溶液质量比为 1.5∶1，GA 添加量为 2.0% 时，所得 BZ_1.5PG_2.0 的拉伸强度与断裂伸长率较纯 PVA 水凝胶（H_1.5PG_2.0）分别提高了 75.7% 和 330.2%。（2）BZ_1.5PG_2.0 具备良好的导电性与抗冻性：在–20 ℃ 条件下，其离子电导率仍保持在 5.1 S/m，且柔韧性良好，可自由弯折而不破裂。（3）BZ_1.5PG_2.0 具有优异的长期稳定性与保水能力：室温放置 40 d 后，其质量损失率仅为 22.4%，显著低于对照组 H_1.5PG_2.0。（4）基于 BZ_1.5PG_2.0 组装的柔性应变传感器对外界刺激表现出灵敏而稳定的响应，并可实现对人体运动状态的可靠监测。【结论】通过构建 BDP/Zn²⁺刚性导电网络与 PVA/GA 柔性网络相结合的复合结构，成功制备出一种力学性能优异、导电性高、抗冻性好的生物质基复合水凝胶。该水凝胶原料可再生，制备简便，综合性能突出，在可穿戴柔性传感器等领域具有广阔的应用前景。

Abstract

[Objective] The mechanical flexibility and low temperature adaptability of hydrogels are crucial for their application in flexible sensors. However, the existing poly(vinyl alcohol) (PVA) hydrogels are prone to freezing and failure at low temperatures, and it remains difficult to simultaneously improve their mechanical properties, conductivity, and environmental stability, which restrict their practical use under complex deformation and extreme environmental conditions. Therefore, this study aimed to develop a composite hydrogel with anti-freezing capability, high conductivity, and excellent mechanical performance to meet the requirements of flexible electronic devices in variable environments. [Method] In this study, bamboo dissolving pulp cellulose (BDP) was used as the raw material, and a zinc bromide (ZnBr₂) solvent system was employed to dissolve BDP and construct a rigid conductive BDP/Zn²⁺ network. This network was then incorporated into a flexible poly(vinyl alcohol) network (PVA/GA) through glutaraldehyde (GA) chemical crosslinking combined with one freeze-thaw, thereby preparing a composite hydrogel (BZPG) with excellent overall performance. [Result] (1) Synergistic effect of BDP and Zn²⁺ significantly enhanced the mechanical properties of the BZPG hydrogels. When the mass ratio of BDP/ZnBr₂ solution to PVA solution was 1.5∶1 and the GA content was 2.0 wt%, the tensile strength and elongation at break of the obtained BZ_1.5PG_2.0 were increased by 75.7% and 330.2%, respectively, compared with the PVA hydrogel (H_1.5PG_2.0). (2) BZ_1.5PG_2.0 exhibited excellent conductivity and freeze resistance. Under –20 ℃ conditions, its ionic conductivity remained as high as 5.1 S/m, while the hydrogel still maintained good flexibility and could be bent freely without fracture. (3) BZ_1.5PG_2.0 demonstrated long-term stability and water retention. When stored at room temperature for 40 days, its mass loss rate was only 22.4%, which is significantly lower than that of the H_1.5PG_2.0 hydrogel. (4) The flexible strain sensors assembled from the BZ_1.5PG_2.0 hydrogel showed sensitive and stable signal responses to external stimuli, enabling reliable monitoring of human motion. [Conclusion] A biomass-based composite hydrogel with high mechanical strength, high conductivity, and excellent freeze resistance was successfully developed by integrating a rigid BDP/Zn²⁺ conductive network with a flexible PVA/GA network. Owing to its simple fabrication process, renewable raw material, and outstanding comprehensive performance, this hydrogel showed great potential for application in wearable flexible sensors.

关键词

生物质基水凝胶 / 离子凝胶 / 抗冻水凝胶 / 离子导电 / 力学性能 / 溴化锌 / 柔性应变传感 / 可穿戴电子

Key words

biomass-based hydrogel / ionic gel / anti-freezing hydrogel / ionic conductivity / mechanical properties / zinc bromide / flexible strain sensing / wearable electronics

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基金资助

国家自然科学基金项目(32571986)