Design And Synthesis Of CO₂-philic Poly（Vinyl Acetate） Based Copolymers

Carbon dioxide (CO2) flooding can not only effectively enhances oil recovery but also considerably reduces greenhouse gas emissions. The low viscosity of CO2, however, leads to viscous fingering in the oil reservoirs, which in turn leads to early CO2breakthrough and depressed oil production rates. The development of CO2thickener that could change the CO2viscosity would have profound effects on oil recovery and is worth pursuing. However, the use of CO2thickener has been limited by the fact that CO2is a very feeble solvent for polar solutes and high-molecular weight polymers. In this work, a library of statistical copolymers of vinyl acetate (VAc) and alkyl vinyl ether (AVE) was synthesized by RAFT polymerization with varying compositions and molecular weights, among which CO2-philic copolymers were selected by the measurement of cloud point pressures. The key factors determining the extent of dissolution of polymer in CO2had been explored by comparing the results of experiments and results of simulation (ab initio molecular orbital methods and molecular dynamics simulation).An new scheme for the synthesis of statistical copolymers of vinyl acetate (VAc) and vinyl trifluoroacetate (VTFAc) has been proposed, i.e., alcoholysis-acylation scheme. Compared with the traditional RAFT polymerization scheme, the cost would be much lowered and the molecular weight and structure of the copolymers could be controlled more effectively.