Synthesis and characterization of poly (l-lactide/ε-caprolactone) statistical copolymers with well resolved chain microstructures

In view of the improved properties of elastomeric copolymers with a random distribution of sequences (randomness coefficient (R) → 1), several synthesis of statistical poly(l-lactide/ε-caprolactone) (PLCL) copolymers at a 75:25 mass feed ratio were conducted evaluating the polymerization conditions (temperatures, times of reaction and comonomer/catalyst (M/C) molar ratios). The mechanisms of reaction of both catalyst employed, SnOct2 and BiSS, differed in the coordination and activation of the monomers leading to different chain microstructures. BiSS was found to be less prone to react with the monomer with higher reactivity, i. e., lactide (LA), than SnOct2, and consequently, the desired random PLCLs (R > 0.85) were obtained. In contrast, the more reactive SnOct2 exhibits a tendency to favor blocky sequences (R