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

Understanding 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) of D-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)(2) was a more efficient initiator than the commonly reported initiating systems of Sn(Oct)(2) and Sn(Oct)(2)/nBuOH in terms of producing higher polymerization rates and polymer molecular weights. High-molecular-weight poly(D-lactide) (1.8 x 10(5) Da) with moderate dispersity (D = 1.3) was obtained using 0.1 mol% liquid Sn(OnBu)(2) as the initiator at 120 degrees C. This work describes the applications of non-isothermal DSC and isoconversional methods in comparing the effectiveness of different initiators in the bulk ROP of D-lactide for the first time. (c) 2023 Society of Chemical Industry.

Automated summary

Understanding 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. This study investigated the kinetics of D-lactide polymerization using different initiating systems, and found that liquid tin(II) butoxide (Sn(OnBu)(2)) was a more efficient initiator compared to other commonly used systems. High-molecular-weight poly(D-lactide) with moderate dispersity was obtained using 0.1 mol% liquid Sn(OnBu)(2) as the initiator at 120 degrees C.