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

AbstractThe 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 ΔH(L‐lactide) = −24,9 kJ/mol; ΔS(L‐lactide) = −25 J/(mol·K) and ΔH(ϵ‐caprolactone) = −15,35 kJ/mol; ΔS(ϵ‐caprolactone) = −35 J/(mol·K).