Suspension polymerization of thermally expandable microcapsules with core-shell structure using the SPG emulsification technique: Influence of crosslinking agents and stabilizers

With aiming to prepare microcapsules having a particle size of 30-50 μm, thermally expandable capsules with relatively uniform particle sizes consisting of a n-octane/poly(acrylonitrile-co-methyl methacrylate) core/shell structure were synthesized using SPG membrane emulsification and suspension polymerization. Four steric stabilizers and five crosslinking agents were employed. When poly(vinyl alcohol) as a stabilizer was used, the prepared capsules showed a smooth and regular morphology and the liquid hydrocarbon (n-octane) was well encapsulated in the core. When 1,4-butnaediol methacrylate (BDDMA) was used as a crosslinker, the uniform capsules with the average diameter of 36.8 μm were synthesized. The capsules prepared with 0.05 mol% BDDMA showed the best encapsulation efficiency.