RAFT Polymerization In Supercritical CO₂

Supercritical CO2is an environmentally friendly green solvent, for it is non-toxic, harmless, inexpensive, nonflammable, non-polluting, easy recovery and recycling. It can greatly reduce the harm to the environment to alter traditional organic solvent with supercritical CO2as a polymerization medium, and it is a green method widely applied. Supercritical CO2technology and living/controlled radical polymerization were organically combined in this thesis so as to prepare polymers with controllable molecular weight and structures by RAFT polymerization in environmentally friendly medium.In this thesis, several kinds of homopolymer and block copolymers (PFOA, PFOA-PMMA-POFA and PDMS-PS) were prepared via RAFT polymerization in supercritical CO2. The molecular weights, structures and polymerization kinetics were investigated by1HNMR.,IR, GPC. DSC and so on. The morphology and macrostructure of block copolymers were characterized by SEM. TEM and XRD. The results showed that all the polymers have controlled molecular weights and expected structure. It was also found that the RAFT polymerization of FOA monomer in scCO2is a homogeneous polymerization process, while the procedure of preparing block copolymers is a dispersion polymerization, using the block copolymer itself as the dispersion stabilizer.