Poly(methyl methacrylate) copolymer nanocapsules containing phase-change material (n-dodecanol) prepared via miniemulsion polymerization

Abstract

Poly(methyl methacrylate) copolymer nanocapsules containing the phase-change material n-dodecanol, which could be used for energy storage, were prepared with different comonomers via miniemulsion polymerization. The thermal properties, morphology, and composition of nanocapsules were characterized with differential scanning calorimetry, thermogravimetric analysis, transmission electron microscopy, and Fourier transform infrared spectroscopy. The results show that the thermal properties and morphology of the nanocapsules were influenced greatly by the type and amount of comonomers. Under the same dosage of 4 wt %, the nanocapsules prepared with the comonomer acrylamine and which had a moderate hydrophilicity showed the highest phase-change latent heat of 109.3 J/g; the acrylamine that had a moderate hydrophilicity and the highest encapsulation efficiency of 91.3%. The size of the nanocapsules ranged from 50 to 100 nm with a uniform spherical shape and apparent core-shell structure. We also found that when the amount of the soft comonomer butyl acrylate was increased, the phase-change latent heat of the nanocapsules first decreased slightly, then increased to the maximum value with deformed spherical and conglutinated morphology, and finally decreased continuously. The thermal stability of the nanocapsules became weaker with higher contents of core material.