Phase change material nanocapsules for latent function thermal fluids with tuneable thermal energy storage profiles†

Abstract

Phase change materials (PCMs) can capture and release thermal energy in the form of latent heat and PCMs as liquid dispersions are known as latent function thermal fluids. For these dispersions, the PCMs are encapsulated to warrant colloidal stability. Here, capsule formation of mini-emulsions of various methacrylates in the presence of trimethylolpropane trimethacrylate (TMA) as a crosslinker, and n-hexadecane (HD), n-octadecane (OCT), and n-docosane (DOC) as PCM was investigated. An ω-unsaturated poly(n-butyl methacrylate-b-[(methacrylic acid)-co-(methyl methacrylate)]) macromonomer was used as a reactive macromolecular emulsifier. The mini-emulsion polymerizations, capsule fabrication and performance were optimized. The resulting latent function thermal fluids and their dried equivalents were studied with differential scanning calorimetry (DSC). A challenge of these materials is matching the temperature range of the application to that of their phase change. The performance of a thermal fluid of DOC nanocapsules was tested against the base fluid water with promising results. As a tunability concept, crosslinked poly(methyl methacrylate) nanocapsules of n-octadecane (OCT) and n-docosane (DOC) were blended as a tuneable latent function thermal fluid.