Use of non‐isothermal DSC in comparative studies of tin(II) systems for the ring‐opening polymerization ofd‐lactide

Abstract

AbstractUnderstanding the kinetics and mechanisms of polymerization, particularly the role of a catalyst or initiator used, allows for the manipulation and control of the fabrication of new materials by the most convenient, straightforward routes. The kinetics of the bulk ring‐opening polymerization (ROP) ofd‐lactide, a useful monomer employed to control the properties of poly(l‐lactide), have been studied herein to identify a relatively quick (1 h), controlled, yet convenient route to moderately high molecular weight poly(d‐lactide). Tin(II) octoate (Sn(Oct)2), Sn(Oct)2/n‐butanol (nBuOH) and liquid tin(II) butoxide (Sn(OnBu)2) as initiating systems were investigated by non‐isothermal differential scanning calorimetry (DSC). Isoconversional methods were employed to determine the activation energy (Ea) for each reaction. The results showed that liquid Sn(OnBu)2was a more efficient initiator than the commonly reported initiating systems of Sn(Oct)2and Sn(Oct)2/nBuOH in terms of producing higher polymerization rates and polymer molecular weights. High‐molecular‐weight poly(d‐lactide) (1.8 × 105 Da) with moderate dispersity (Ð = 1.3) was obtained using 0.1 mol% liquid Sn(OnBu)2as the initiator at 120 °C. This work describes the applications of non‐isothermal DSC and isoconversional methods in comparing the effectiveness of different initiators in the bulk ROP ofd‐lactide for the first time. © 2023 Society of Chemical Industry.