Polymerization of L ‐lactide and ϵ‐caprolactone in the presence of methyl trifluoromethanesulfonate

The cationic polymerization of L ‐lactide and ϵ‐caprolactone initiated by methyl trifluoromethanesulfonate in nitrobenzene was studied. The monomer conversion and the average molecular weight decrease when the temperature increases. The kinetics constants for L ‐lactide and ϵ‐caprolactone polymerizations are, respectively, equal to 1,7·10 −3 min −1 and 1,60·10 −3 min −1 at 50°C. The thermodynamic parameters were determined from the temperature dependence of the equilibrium monomer concentration. Thus for L ‐lactide and ϵ‐caprolactone polymerization the enthalpy and entropy values are, respectively, equal to Δ H ( L ‐lactide) = −24,9 kJ/mol; Δ S ( L ‐lactide) = −25 J/(mol·K) and Δ H (ϵ‐caprolactone) = −15,35 kJ/mol; Δ S (ϵ‐caprolactone) = −35 J/(mol·K).