Polystyrene shell-based “coconut-like” and “pomegranate-like” microencapsulated phase change materials: Formation mechanism, thermal conductivity/stability enhancement and their application in thermal management

Abstract

Encapsulation of phase change materials (PCMs) using polystyrene (PS) can be an effective solution to the leakage of PCMs, but the low thermal conductivity/stability of the prepared microencapsulated phase change materials (MEPCMs) remain unresolved. Here, we investigated the formation mechanism of PS shell-based MEPCMs via Pickering emulsion polymerization: coconut-like and pomegranate-like MEPCMs were obtained for the first time before and after the introduction of divinylbenzene (DVB), and the thermal conductivity and stability of the former were lower than that of the latter with the same graphene nanosheets (GNSs). Among them, MEPCM-4–7 wt% GNSs (St:DVB=1:1) has the highest thermal conductivity of 0.9358 W∙m−1∙k−1 (222.47 % higher than MEPCM without GNSs) and optimal anti-leakage performance. The thermal stability (thermogravimetric results) is slightly weaker than MEPCM-3–7 wt% GNSs (St:DVB=5:1), but has the highest thermal reliability (the melting enthalpy only decreases by 0.19 % after 100 cycles). The phase change composites (PCCs) was prepared by dispersing MEPCMs in PDMS matrix and applied to the simulated chip thermal management, which can achieve a 10.85 % decrease in the chip equilibrium temperature compared with PDMS. The method of improving the heat transfer properties and thermal stability of MEPCMs based on their structure provides a new idea to solve the problem of low thermal conductivity and stability of MEPCMs, and the prepared PCCs show great potential for practical applications in the field of thermal management.