Synthesis of n-octadecane/poly (styrene-methyl methacrylate) (St-MMA) energy-storage microcapsules via emulsion polymerization

Poly (methyl methacrylate) block copolymer is interesting due to its good compatibility with many polymers. In this study, a novel phase-change energy storage material, n-octadecane/poly (styrene-methyl methacrylate) (OD/P(St-MMA)) microcapsules, were designed and synthesized by emulsion polymerization, in which n-OD was used as core materials, the copolymer of St and MMA as shell materials, and sodium dodecyl benzene sulfonate (SDBS) as emulsifier. The morphology, phase-change thermal properties and thermal stability of microcapsules were investigated by particle size analyzer, transmission electron microscope, thermogravimetric (TG) analyzer, and differential scanning calorimetry (DSC). The results showed that when the ratio of the two monomers, St and MMA, was 1/5 and the dosage of SDBS was 1.5 g (3% of the total mass), the particle size dispersion of microcapsules was uniform and microcapsule particles were well wrapped. TG analysis showed that the long-term use temperature of microcapsules could not exceed 131°C. DSC showed that the phase-change enthalpy of microcapsule was 148.39 J·g −1 , which indicated the microcapsules had excellent energy storage property.