CO2-solubility of oligomers and polymers that contain the carbonyl group

Poly(vinyl acetate) (PVAc) is miscible with CO2 over a broad range of molecular weights at 298 K. The cloud-point pressures needed to dissolve ∼5 wt% poly(methyl acrylate) (PMA) at 298 K are significantly greater than those needed to dissolve PVAc, even though a PMA repeat group has the same number of carbon, hydrogen, and oxygen atoms as in PVAc. This large difference in dissolution pressures is attributed to the lack of accessibility of the carbon dioxide to the carbonyl group in PMA. In addition, experimental data for poly(dimethyl siloxane) (PDMS) copolymers with readily accessible side groups suggest that an acetate group is slightly more CO2-philic than an acrylate group. PVAc is more CO2-soluble than other hydrocarbon homopolymers, including poly(propylene oxide) (PPO) and poly(lactide) (PLA). However, PVAc is significantly less miscible with CO2 than PDMS and poly(fluoroalkyl acrylate) (PFA).