Liquid metal/cyclodextrin composite biomimetic memory hydrogel

doi:10.11949/0438-1157.20250237

Abstract

Abstract:

The liquid metal (LM)/β-cyclodextrin (CD) composite was prepared by compounding liquid metal (LM) with β-cyclodextrin (CD) through a solvent-free stirring strategy. This composite was used as an initiator to trigger the copolymerization of acrylamide (AAm) monomers, successfully synthesizing hydrogels with gradient LM/CD distribution. The hydrophobic cavity of CD can encapsulate LM droplets, and its surface hydroxyl groups form physical anchors with LM through coordination interactions. Combined with the steric hindrance effect to inhibit particle agglomeration, this method can effectively disperse 60% (mass fraction) of LM under stirring conditions of 2000 r/min for 30 min, allowing LM/CD to form a self-supporting and conductive lamellar structure. The bottom resistance of LM/CD hydrogel was changed by tapping to induce directional precipitation of LM. Electrochemical tests showed that the bottom resistance of LM/CD hydrogel was linearly related to the number of tapping, which could realize bionic memory function and keep the resistance stable during compression-release cycle. Compared with traditional conductive polymer-modified hydrogels, this material combines high conductivity (bottom surface resistance 0.808 Ω), excellent mechanical properties, and stable memory behavior, providing new ideas for the design of intelligent biomimetic materials.

Key words: gels, biomimetic memory, liquid metal, cyclodextrin, conductivity, agglomeration, polymers

摘要：

通过无溶剂搅拌策略将液态金属（LM）与β-环糊精（CD）复合制备液态金属/β-环糊精（LM/CD）复合物，并以此为引发剂引发丙烯酰胺（AAm）单体共聚，成功合成具有梯度LM/CD分布的水凝胶。CD的疏水空腔可包封LM液滴，其表面羟基通过配位作用与LM形成物理锚定，结合空间位阻效应抑制颗粒团聚，在搅拌转速2000 r/min、时间30 min条件下可有效分散60%（质量分数）的LM，LM/CD可形成具有自支撑性与导电性的片层结构。通过敲击诱导LM定向析出使LM/CD水凝胶底部电阻发生变化，电化学测试表明，LM/CD水凝胶底面电阻与敲击次数呈线性关系，可以实现仿生记忆功能且在压缩-释放循环中电阻保持稳定。与传统导电聚合物改性水凝胶相比，该材料兼具高导电性（底面电阻0.808 Ω）、优异力学性能及稳定的记忆行为，为智能仿生材料设计提供了新思路。

关键词: 凝胶, 仿生记忆, 液态金属, 环糊精, 导电性能, 团聚, 聚合物

CLC Number:

O 69

Xingyue LIN, Xiubin XU, Xin LI, Linjie WEI, Hao WANG, Xi YAO, Xu WU. Liquid metal/cyclodextrin composite biomimetic memory hydrogel[J]. CIESC Journal, 2025, 76(11): 6077-6085.

林星月, 徐秀彬, 李鑫, 韦林洁, 王灏, 姚希, 吴旭. 液态金属/环糊精复合仿生记忆水凝胶[J]. 化工学报, 2025, 76(11): 6077-6085.

Figures/Tables 14

Fig.1 Preparation diagram of LM/CD

Fig.2 Effect of stirring speed on liquid metal dispersion: images of LM/CD composite at different rotation speeds

Fig.3 TEM images and corresponding EDS element mapping diagrams of LM/CD 60 composites at different stirring speeds

Fig.4 LM/CD 40 (a), LM/CD 50 (b), LM/CD 60 (c), and LM/CD 70 (d) composites and their partially enlarged electron images at a rotation speed of 2000 r/min

Fig.5 SEM images of LM/CD 40 (a), LM/CD 50 (b), LM/CD 60 (c), LM/CD 70 (d) composites with 2000 r/min, as well as corresponding EDS images

Fig.6 FTIR spectra of CD and LM/CD

Fig.7 Schematic diagram of principle of self-supporting film conductivity (circle represents LM, and trapezoid represents CD)

Fig.8 Electrical conductivity of layered materials compressed under different pressures, composed of LM/CD with varying liquid metal contents

Fig.9 Illustrates self-supporting capability (a) and good lamellar conductivity (b) of LM/CD 60 under a pressure of 4 MPa

Fig.10 Mechanical properties of LM/CD hydrogels with varying LM content

Fig.11 Resistance variation with number of taps

Fig.12 Elemental distribution analysis of LM/CD organogel: (a) cross-sectional secondary electron image of gel, and (b) gallium (Ga) and (c) indium (In) elemental mappings, respectively； (d) secondary electron image of upper gel surface, and (e) corresponding elemental mappings (O, In, Ga, C)； (f) secondary electron image of pristine lower gel surface, and (g) corresponding elemental mappings (O, In, Ga, C)； (h) secondary electron image of lower gel surface after 300 cycles of tapping, and (i) corresponding elemental mappings (O, In, Ga, C)

Table 1 Elemental composition of top surface and bottom surface of hydrogel by EDS

元素	含量/%（质量分数）
元素	上表面	下表面
C	60.83	41.98
O	35.16	20.12
Ga	3.44	28.58
In	0.57	9.32
总量	100.00	100.00

Fig.13 Resistance recovery of hydrogels under stretching and releasing conditions: a graph showing resistance changes during stretching and releasing

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