Vinyltrimethoxysilane-Functionalized Zinc Oxide-Mediated Green Photopolymerization of Multinetwork Conductive Eutectogels for Wearable Strain Sensing

Abstract

Current strategies for preparing conductive hydrogels (CHs) often inevitably encompass the addition of small-molecule photoinitiators, toxic cross-linkers, or complex polymerization conditions, limiting their broader application in flexible wearable electronics. To address these issues, we developed a green in situ photoinitiation and organic–inorganic hybrid cross-linking strategy based on vinyltrimethoxysilane-modified zinc oxide (VTMS-ZnO). By constructing a deep eutectic solvent (DES) system composed of betaine (BET), itaconic acid (IA), and glycerol (Gly), integrated through poly(ethylene glycol) diacrylate (PEGDA) covalent cross-linking, hydroxyethyl cellulose (HEC) chain entanglement, Zn²⁺ dynamic coordination, and DES-induced multiple hydrogen-bonding interactions, we successfully fabricated HEC@P(2-hydroxyethyl methacrylate-co-sodium 4-styrenesulfonate) [P(HEMA-co-NaSS)]/VTMS-ZnO semi-IPN conductive eutectogels. In this system, VTMS-ZnO serves as the photoactive inorganic component to induce the in situ copolymerization of HEMA and NaSS under UV irradiation. Moreover, the surface vinyl groups of VTMS-ZnO participate in the network construction, allowing the ZnO nanoparticles to be embedded into the polymer network as hybrid nodes. The optimized H_0.2 eutectogel demonstrated an elongation at break of approximately 1000%, a toughness of 96.96 kJ m^–3, an ionic conductivity of 78.2 mS m^–1, a gauge factor of 0.270, and an adhesion strength of 6.11 kPa on paper. It maintained stable sensing performance over 150 cycles at 10% strain, remained flexible after storage at −53 °C for 12 h, and retained over 50% of its initial mass at 37 °C and 35% relative humidity for 11 days. This comprehensive performance enables the eutectogels to serve as versatile wearable sensors for the real-time monitoring of human movements and weak physiological signals (response time of 0.82 s). In addition, the eutectogel exhibited inhibitory activity against Escherichia coli. Our work sheds light on a feasible and eco-friendly strategy for customizing multifunctional eutectogels, paving the way for innovative flexible wearable devices.