Reversible Phase-Change-Induced Transparency Switching and Dynamic Thermal Regulation Gel for Energy-Efficient Smart Windows

Abstract

Inefficiencies in window thermal management account for a substantial portion of energy losses in buildings, highlighting the urgent need for advanced, energy-efficient active thermal control measures in architectural design. In this study, we present a novel strategy that integrates eutectic phase change materials (lauric acid and methyl palmitate) within a poly (methoxyethyl acrylate) organic gel framework, denoted as PEPG, which achieves temperature-responsive optical transparency switching and passive thermal regulation. By leveraging crystal-melt phase transitions, the proposed system achieves dual-mode regulation: It facilitates energy-efficient daylighting through a transparent homogeneous phase at temperatures exceeding the fusion threshold (T_lum = 96.03%) while simultaneously providing privacy protection via a microphase-separated heterogeneous phase at temperatures below the solidification threshold (ΔT_sol = 77.13%). Notably, the temperature-induced reversible phase transition allows for dynamic regulation of heat (ΔH_m = 130.10 J/g) without requiring auxiliary energy input, thereby enabling autonomous maintenance of indoor temperatures within the human thermal comfort zone (20°C–26°C). Furthermore, the tailorable crosslinking density of PEPG extends its applicability into wearable thermal management suits and adaptive heat-dissipation interfaces for compact electronics. This work establishes a new paradigm for multifunctional soft materials, effectively bridging the gap between energy-saving technologies and personalized thermal comfort solutions.

Keywords

advanced thermal management / energy storage / eutectic phase change materials / smart windows / temperature response

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