Styrenation of air blown linseed oil via RAFT-mediated miniemulsion polymerization

In this study styrenated oil products were prepared under miniemulsion conditions by reversible addition-fragmentation chain transfer polymerization (RAFT) technique using phenacyl morpholine dithiocarbamate (PMDC) as a RAFT agent. First, hydroperoxide groups were formed on the oil structure by air-blowing process. Then the prepared miniemulsion of air blown linseed oil (ABLO)-styrene mixture was subjected to styrenation in the presence of the RAFT agent. Miniemulsion was prepared by means of ultrasonication by using cetyl trimethyl ammonium bromide (CTAB) and hexadecane (HD) as surfactant and co-surfactant, respectively. The best miniemulsion conditions were determined by a new strategy based on the determination of the conditions ensuring not to change of droplet/particle size throughout the polymerization. In this way, the conditions for the elimination of monomer diffusion between droplets were established. The styrenated oil product obtained under optimum conditions was characterized by FT-IR, 1H NMR and GPC measurements. In order to understand the effect of miniemulsion conditions on molecular weight and polydispersity index (PDI), styrenated oil samples were also prepared in solvent (dioxane) medium. Tests for film properties of product prepared by RAFT in miniemulsion medium were applied according to related standards. The styrenated oil obtained in this study exhibited molecular weight distribution values lower than styrenated oil products obtained by the classical RAFT polymerization in solvent medium. The film properties showed that these styrenated oil samples could be used as an oil based binder.