Fabrication of Core-Shell, Janus, Dumbbell, Snowman-Like and Confetti- Like Structured Microspheres of Blends of Poly (4-butyl triphenylamine) and Poly (methyl methacrylate) by Solvent Evaporation Method

Polymeric blend particles consisting of poly(4-butyl triphenylamine) (PBTPA) and poly(methyl methacrylate) (PMMA) with various phase separated morphologies including core-shell, Janus, dumbbell and confetti-like structures were prepared by a solvent evaporation method in which a solvent is evaporated from polymer solution droplets dispersed in an aqueous medium. The effects of the preparation conditions including solvent, molecular weight, content of polymers and evaporation rate on the morphology were investigated in detail. The morphology of the particles prepared from toluene solution changed from core-shell to Janus with the increase of the molecular weight of the PMMA. The particles prepared from chloroform solution exhibited dumbbell-like structure independent of the molecular weight. It was found that poly(vinyl alcohol) (PVA) as a suspension stabilizer in aqueous medium reduced the interfacial tension between the chloroform solution and the aqueous phase to less than 5 mN m­1. Snowman-like particle as the series of dumbbell-like structure was obtained by decreasing the weight ratio of the PBTPA. Rapid evaporation of chloroform induced the formation of confetti-like structure with the PMMA core surrounded by the PBTPA particles of less than 1 µm in diameter.