Novel P-N-Si synergistic phase-change material microcapsules for building coatings with smart temperature control and fire safety functions

In order to save building energy consumption and improve the comfort of building occupancy, functional building coatings are widely used. Introducing microencapsulated phase change materials into epoxy resin coatings can endow them with temperature-control properties. To enhance the fire safety of buildings, this study, for the first time, couples P-N-Si three-element synergistic flame retardancy with phase-change thermal control. Hexachlorocyclotriphosphazene (HCCP) and silane coupling agent (3-Aminopropyl)triethoxysilane (APTES) was used as raw materials to prepare a new type of P-N-Si synergistic flame retardant (APZ) through nucleophilic substitution reaction. The introduction of APZ endows epoxy resin (APZ-PCM/EP) with excellent flame-retardant properties, and the peak heat release rate and total smoke production of APZ-PCM/EP are reduced by 22.9 % and 27.3 % respectively. Furthermore, the thermal responsiveness and phase change properties of the microcapsules modified with APZ (APZ-PCM) are enhanced, with the onset temperature of phase change occurring 1.5 °C earlier than that of MPCM. More importantly, the indoor temperature in the small-scale model room using APZ-PCM/EP is reduced by 29.5 % compared to that of the pure epoxy resin. This study presents a viable route to integrate fire safety with thermal comfort and offers a new strategy for smart temperature-control intumescent coatings on building exterior walls.