Synthesis of Core-Shell Particles with Low Molecular Weight Alkanes by Miniemulsion Polymerization

摘要

Miniemulsion polymerization technique was used to obtain core-shell nanoparticles with a core of low molecular weight alkanes and a polystyrene shell. Reactions were performed at 80°C for 5 hours using benzoyl peroxide as oil-soluble initiator. The effect of different alkane types, namely n-hexadecane, n-octane and n-heptane, and initiator concentrations on reaction rates, particle sizes, molecular weights and particles morphology were evaluated. When shorter chain alkanes as n-heptane and n-octane were used it was observed lower reaction rates, higher particle sizes and less sharp particle morphology than in reactions with hexadecane in which well formed core-shell particles were obtained. These results were assigned to the plasticizing effect and higher water-solubility of n-octane and n-heptane, responsible for decreasing the gel effect and favoring the diffusional degradation.