Stabilizer-free precipitation copolymerization of renewable bio-based α-methylene-γ-butyrolactone and styrene

Stabilizer-free precipitation copolymerization of α-methylene-γ-butyrolactone (MBL) and styrene (St) was carried out in isoamyl acetate with BPO as initiator at 80°C. The influence of monomer feed ratio, initiator concentration and reaction time on the size and morphology of the obtained polymer particle was investigated in details. It was found that the monomer feed ratio play an important role on the particle formation process. When the monomer feed ratio of MBL to St was 1:2, narrow size distributed spherical polymer particles were formed with number average diameters in the range of 785–2620 nm. The formation process of polymer particle was studied to get a deep insight into the polymerization process of this reaction system. It was found that the formation mechanism of the poly(MBL-co-St) particles was similar to that of conventional precipitation polymerization. After a short nucleation stage (10 min), the amount of polymer particles remained constant and the particle growth mainly came from the capturing of newly formed polymer chains. The chemical composition and thermal property of the poly(MBL-co-St) were fully characterized by FTIR, ¹H-NMR spectra, and DSC.