Synthesis of oligomer vinyl acetate with different topologies by RAFT/MADIX method and their phase behaviour in supercritical carbon dioxide

Poly(vinyl acetate) (PVAc) has been shown to exhibit anomalously high solubility in CO₂ as compared to other vinyl hydrocarbon polymers. Understanding the phase behaviour of PVAc with different topologies in CO₂ is very important for its potential applications as suitable surfactant, or phase transfer agent in a CO₂ solvent process. In this study, a series of PVAcs with different topologies (bi-arms, tri-arms, tetra-arms) were synthesized by RAFT/MADIX method. The structures and molecular weights of these polymers were characterized by ¹H NMR and GPC. The phase behaviours of PVAcs in dense carbon dioxide fluid were determined, and the results show that the PVAc with more arms has lower cloud point pressure.