Heterocyclic aramid-based phase change films created via oil-in-oil emulsion technology with multiple energy conversion, thermal regulation, and electromagnetic shielding properties

Abstract

Phase change material (PCM) has demonstrated significant potential in solar energy utilization and thermal management owing to its high energy density and isothermal phase transition. Nevertheless, the inherent leakage risks and limited energy source hindered their widespread application. Herein, multifunctional heterocyclic aramid-based phase change films filled with n-octadecane (OD) were prepared via oil-in-oil emulsion template and emulsion coating technique. Within this framework, OD was encapsulated using a composite matrix composed of heterocyclic Heterocyclic aramid (HA), carbon fibers and carbon nanotubes, forming an OD-in-HA/C non-aqueous emulsion, followed by emulsion coating to yield flexible HA/C/OD phase change films. The resulting HA/C/OD films exhibit good mechanical strength (5.1 MPa), a high enthalpy (92.8 J/g), minimal supercooling, and almost no leakage. Their superior phase transition properties remain stable even after 80 thermal cycles. Moreover, the embedded carbon nanotubes and carbon fibers impart high electrical conductivity, efficient electro- and photo-thermal conversion, and hygrovoltaic electricity generation. Leveraging their combined latent heat and conductivity, the films also served as an ideal candidate for information encryption and electromagnetic shielding. This research provides an innovative and scalable strategy for preparing multifunctional polyamide-based PCMs, paving the way for more efficient energy utilization and conversion.