Poly(vinyl acetate), poly((1-O-(vinyloxy) ethyl-2,3,4,6-tetra-O-acetyl-β-d-glucopyranoside) and amorphous poly(lactic acid) are the most CO2-soluble oxygenated hydrocarbon-based polymers

Poly(vinyl acetate), PVAc, remains the most CO2-soluble non-fluorous polymer identified to date. Small sugar acetates are known to be extraordinarily CO2-philic, but cellulose triacetate, a crystalline high molecule weight polymer is CO2 insoluble. Therefore, an amorphous high molecular weight polymer with pendant sugar acetates was synthesized. This polymer, poly(1-O-(vinyloxy) ethyl-2,3,4,6-tetra-O-acetyl-β-d-glucopyranoside, P(AcGIcVE), was indeed CO2-soluble, however cloud point pressures of P(AcGIcVE) at 5 wt% polymer and 298 K were greater than that required for the dissolution of PVAc. Finally, the solubility of amorphous poly(lactic acid), PLA, was determined over a wide range of molecular weight. The corresponding cloud point pressures were much greater than either PVAc or P(AcGIcVE). Ab initio calculations for the CO2/PVAc dimer and CO2/PLA dimer mixtures were conducted in an attempt to elucidate the dramatic differences in the cloud point values of PVAc and PLA. Our calculations indicate that there is little difference in the average interaction energies for the CO2/PLA and the CO2/IPA systems. The only indication that PVAc would be expected to be more CO2-soluble that PLA was that the vinyl acetate dimer has binding modes that will readily accept multiple CO2 molecules, whereas the binding modes for the lactic acid dimer can apparently only accommodate a single CO2 molecule at a time.