Synthesis of hemispherical Poly(2-hyroxylethyl methacrylate-co-methyl methacrylate)/Poly(styrene-co-glycidyl methacrylate)composite Particles with Heterobifunctional Groups by Soap-Free Seeded Emulsion Polymeirzation

摘要

Poly(2-hydroxylethyl methacrylate-co-methyl methacrylat)/poly(styrene-co-glycidyl mthacrylate)(P(HEMA-MMA))/P(St-GMA))composite polymer particles wer prepared by soap-free seeded emulsion polymerization.The P9HEMA-MMA) seed latexescross-;inked by 0,10,and 20 wt% ethylene glycol idmethacrylate (EGDMA)wereprepared by soap-free emulsion polymerizaton with differetn HEMA/MMA monomer compositionat 80 deg C.2,2'-Azobis(2-amidinopropane)dihydrochloride (-50) was used as an initiator in the two stages.The morphologies f composite particles were investigated by using seed particles with various HEMA content and cross-link degree,and the effects of solvent additionk,preswelling of seed particles by monomers and solvent,and the weight ratio of secondary monomer to seed particles (M/P) on the particle morphology were discussed.Un-cross-linked P(HEMA-MMA)seed latex showed the property of gel particles capable of being swollen by water,which led ot the instabilty of seed particles and a specifi cmorphology variation.In principle,the addition of solvent favors to form thermodynamically and a specific morphology variation.In principle,the addition of solvent favors to form thermodynamically stable morphology,but the preswelling process by monomers and toluene did not affect the particle morphology,possibly because the equilibrium swelling might be already attained during the nitrogen purge and heating intervals under lower M/P ration.Various spherical and anomalous particle morphologies were obtaine dby controlling polymrization conditions;that is,sandwich-like,hemispherical,and microphase-separated spherical particles were formed when the seed particles with lower HEMA content and lower cross-link degree were employed under smaller M/P ratio.On the other hand,dumbbell,popcorn,and bunch of grapes like anomalous particles were formed when the seed particles with lower HEMA content and lower cross-separted degree were employed under smaller M/P ration.On the other hand,dumbbell,popcorn,and bunch of grapes like anomalous paricles were formed under some specific conditions.When the cross-linker,divinylbenzene (DVB),was harged into the seed stage,the anomalous particles were changed to spherical particles due ot the reduction of polymer chain mobility.