Phase Equilibrium Thermodynamics for a Polycarbonate Production Process using Supercritical Carbon Dioxide

摘要

Thermodynamic phase equilibrium data, which are relevant to the development of a novel production process for polycarbonates from CO_2 and epoxides, are presented. In this solvent-free process, CO_2 is coupled to epoxides using various transition-metal catalyst systems. Data on the performance of these systems are discussed. Additionally, the polycarbonate solubility in CO_2 and CHO is considered, both inside and beyond the P-T ranges that have been used for synthesis of the polycarbonate. Moreover, CHO-CO_2 vapour pressure isotherms have been measured and modelled. Experimental results indicate that following the pressure decay during the polymerisation reaction offers a feasible and reliable method for on-line monitoring of monomer conversion. Results are finally discussed in terms of their implication on the development of novel production processes for polycarbonates.