Copper nanoparticles interlocked phase-change microcapsules for thermal buffering in packaging application

Abstract

A novel kind of functionalized copper nanoparticles (CuNPs) interlocked polydivinylbenzene (PDVB) microcapsules containing hexadecane as phase change material (PCM) was synthesized targeting thermal buffering application in food packaging. Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) characterizations confirmed the successful functionalization of CuNPs and their existence in the PDVB shell. Scanning electron microscopy (SEM) results indicated that produced microcapsules exhibited well-defined core–shell microstructure with spherical morphology, and their compositions and chemical structures were confirmed by a series of spectroscopic characterizations. Atomic force microscopy (AFM) results showed that average and mean square roughness is higher in CuNPs/microPCMs than bare microcapsules. Differential scanning calorimetry (DSC) analysis confirmed that microPCM with 1.0% CuNPs achieved a maximum melting enthalpy of 132 J/g with an encapsulation ratio of 60.5% and could maintain it even after 100 melting-freezing cycles. The thermal conductivity was significantly increased by 319.5% as compared with that of bare microcapsules. Most importantly, optimized microcapsules provided an excellent thermal buffering effect of more than 6.5 h for the 240 g of chocolate to raise its temperature from 5 °C to 35 °C, confirming great potential in food packaging application.