Flexible and robust aramid/octadecane phase change materials from nonaqueous emulsion template towards efficient thermal storage and camouflage

[Display omitted] •Dctadecane/aramid phase change materials are prepared via non-aqueous emulsions.•Phase change films exhibit high strength, enthalpy, and stable cyclic performance.•This strategy enables continuous preparation of aramid-based phase change composites. Phase change materials have been widely used in energy storage, temperature regulation, and thermal management. However, the complex preparation process and leakage risk are long-standing bottlenecks for phase change materials. In this work, we report a strategy to encapsulate phase change materials (octadecane, OD) with heterocyclic aramid (HA) via oil-in-oil emulsion platforms (OD-in-HA emulsion), and the OD-in-HA emulsion was further processed into OD/HA phase change films and fibers. These materials feature an HA encapsulation shell and OD as the core, combining HA’s mechanical strength and environmental resistance with OD’s thermal storage properties. The phase change films with 62 % OD not only have excellent tensile strength (14.68 MPa), strain (44.62 %), enthalpy (167.92 J/g) and low subcooling degree but also exhibit almost no leakage (＜4%) and stable cyclic stability, which does not decrease significantly after 40 heating/cooling cycles. Besides, the OD/HA films and fibers possess good infrared stealth and battery thermal management performance. This work proposes a continuous and scalable approach for constructing high-performing aramid-based phase change materials and significantly expanding the application of phase change materials.