A Composite Coating of Octadecane@SiO2-ZnO Microcapsules and MXene/Chitosan-Polyacrylate for Smart Fabrics with Rapid Humidity Sensing and Active Thermal Management

Abstract

Advancing the development of sensitive, rapid-response fabric humidity sensors and textiles with active thermal management is crucial for enhancing wearer safety and user experience in complex environments. Herein, a double-shell microcapsule featuring a rough surface was developed by growing a zinc oxide shell on silica microcapsules. A polyacrylate containing acetoacetate groups was crosslinked with carboxymethyl chitosan, resulting in a stable composite system. This system was further stabilized through electrostatic interactions with MXene nanosheets. The microcapsules were subsequently integrated into a conductive composite coating applied to fabric through a finishing process. Based on effective encapsulation of the phase-change core material, the microcapsules exhibited a phase-change enthalpy of 57.33 J/g, demonstrating excellent thermal energy storage capacity. Due to the hydrophilicity of the protonated amino groups in carboxymethyl chitosan and the active sites on the rough microcapsule surface, the composite coating exhibited a remarkable humidity sensitivity of 10186%. Regarding antibacterial performance, the protonated amino groups in carboxymethyl chitosan synergize with the zinc oxide-containing shell, achieving inhibition rates of 99.78% and 99.99% against E. coli and S. aureus, respectively, demonstrating excellent broad-spectrum antibacterial activity. When applied for perspiration monitoring on human arm, it demonstrated real-time humidity tracking and effective thermal management capabilities, showcasing its promising applications in smart wearable technology.