Ring opening polymerization of lactide in a monomode microwave using stannous octoate and dibutyltin dimethoxide catalysts

Abstract

The ring-opening polymerization of L-lactide to poly(lactic acid), PLA was carried out under N2 atmosphere and microwave irradiation using stannous octoate (SnOct2) and dibutyltin dimethoxide (DBTM) as initiators. The polymerization rate was much faster than that obtained with conventional heating. The polymer was characterized by Heteronuclear Single Quantum Coherence Spectroscopy (1H and 13C-HSQC NMR), Fourier Transform Infrared Spectroscopy (FTIR) and Size Exclusion Chromatography (SEC). The poly(styrene)-equivalent weight-average molar mass (M w) obtained with SnOct2 was 1.02 × 105 g mol -1, while in the case of DBTM, it was only 4.0 × 104 g mol-1 and the corresponding polydispersities varied from 1.2 to 2.4 and 1.6 to 1.8, respectively. A significant degradation of PLA in chloroform solvent was observed for the first time. © 2014 Copyright Taylor & Francis Group, LLC.