Enhanced photothermal conversion and thermal conductivity of phase change n-octadecane microcapsules shelled with nano-SiC doped crosslinked polystyrene

Microcapsules incorporating phase change material n-octadecane (ODE) shelled with crosslinked polystyrene (CLPS) were prepared via the suspension polymerization. SiC nanoparticles (nano-SiC) were employed to modify the shell to improve the heat transfer and photothermal conversion of the microcapsules. The scanning electron microscopic analysis revealed the microcapsules of a general spherical shape. The surface components and chemical composition of the microcapsule samples were evaluated by the energy-dispersive X-ray and Fourier transform infrared spectroscopy, confirming that the nano-SiC have been embedded in the CLPS shell. Results show that the microcapsule sample with 1.25 wt.% nano-SiC (denoted as MPCM3) exhibits the best heat property among the four kinds of samples prepared with various nano-SiC dosages, and all the nano-SiC doped samples have improved thermal conductivity and photothermal conversion as compared to the microcapsule sample without doping (denoted as MPCM1). Compared to the MPCM1, the thermal conductivity of the MPCM3 is increased by 65.3%, reaching 0.124 ± 0.005 W·m⁻¹·K⁻¹. The MPCM3 has excellent thermal stability as well. Differential scanning calorimetry examination shows that the MPCM3 has higher melting and crystallization enthalpies than the MPCM1, achieving 106.8 ± 0.3 J·g⁻¹ and 104.9 ± 0.2 J·g⁻¹, respectively. In the photothermal conversion experiments, the MPCM3 exhibited great photothermal conversion capability, with a 54.91% photothermal conversion efficiency, which is 145.68% higher than that of the MPCM1.