Phase-Change Coatings with Thermoresponsive Transparency for Building Temperature Regulation

摘要

A series of coatings containing solid-solid phase-changing polymeric matrices have been synthesized by thermally initiated polymerization of methacrylate-based precursors. The transmittance of these coatings in the UV to IR wavelength range changes reversibly as a function of temperature, and has been utilized as a design parameter for the development of temperature regulating building enclosures. The latent heat storage capacity of these materials can be controlled by tailoring their composition, crosslink density, and porosity. Shape stable matrices with heats of melting surpassing 120 kJ/g and clear/opaque transmittance ratios larger than 80 can be prepared using this methodology. A combination of finite element simulation and experimental data will be used to discuss the implementation feasibility of these thermoresponsive coatings in different types of building enclosures. Insertion of a 6-atom flexible spacer (diethylene glycol) between the pendant crystalline motif and the polymer backbone resulted in decreased optical contrast between in the melt state and the solid state, but increased latent heat capacity from 45 J/g to 70 J/g, while the thermal conductivity increased from 0.24 W/mK to 0.35 W/mK. Notably, insertion of a flexible spacer also resulted in an increase in the melt transition temperature from 37.7 °C to 48 °C. The study presents a synthetic tool to control thermal and optical properties of the spacer linkage - phase change materials.