Membrane dressing utilizing thermochromic phase change nano-capsules for body temperature monitoring and regulation

This study aimed to synthesize a reversible thermochromic membrane (TC-membrane) using nano-encapsulated phase change materials (NEPCMs) for medical dressings, which possess both body temperature monitoring and regulation functionality. N-Octadecane (C18) was chosen as the core material in NEPCMs to facilitate heat absorption. Crystal violet lactone (CVL) Bisphenol A (BPA) and tetradecanol (C14H29OH) were employed as the thermochromic compound. In addition, polyvinyl alcohol (PVA) and water-based polyurethane (WPU) were used to prepare TC-membrane, and hydroxypropyl methylcellulose (HPC) was used as a modified material to enhance the mechanical properties of TC-membrane. Characterization results revealed that the most optimal color-changing performance was achieved with a mass ratio of CVL to BPA to C14H29OH at 1:3:50. The TC-membrane exhibited a phase transition enthalpy of 22.6 J/g and 31.9 J/g in solidification and melting progress, respectively, demonstrating excellent heat storage capabilities. The addition of HPC enhanced the mechanical properties, resulting in a 37.1 % increase in tensile strength and a 90.8 % increase in elongation at break. Furthermore, the TC-membrane presented rapid responses to temperature variations, with color changes and recoveries occurring within 1 min. This study demonstrated that NEPCMs have a promising potential future in applications related to wearable temperature sensors, energy storage and thermal regulation applications.