UV-Initiated Ring Opening Polymerization of l-Lactide Using a Photobase Generator

Emeline Placet; Julien Pinaud; Olinda Gimello; Patrick Lacroix-Desmazes

doi:10.1021/acsmacrolett.8b00251

UV-Initiated Ring Opening Polymerization of l-Lactide Using a Photobase Generator

ACS Macro Lett. 2018 Jun 19;7(6):688-692. doi: 10.1021/acsmacrolett.8b00251. Epub 2018 May 25.

Authors

Emeline Placet¹, Julien Pinaud¹, Olinda Gimello¹, Patrick Lacroix-Desmazes¹

Affiliation

¹ ICGM, ENSCM, Univ Montpellier, CNRS, 34296 Cedex 5, Montpellier, France.

PMID: 35632978
DOI: 10.1021/acsmacrolett.8b00251

Abstract

Photoinitiated ring-opening polymerization of l-lactide (L-LA) using a photobase generator (PBG) able to release 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) is reported. Polymerization using the PBG with ketoprofenate counteranion (TBDH⁺.keto^-) was studied in dichloromethane either in the presence or in the absence of 1-butanol as initiator. In both cases, full monomer conversion was reached at room temperature after 10 min of irradiation at 254 nm. In the presence of 1-butanol, linear poly(L-LA) chains (PLA) were obtained, as confirmed by ¹H NMR and MALDI-TOF analyses. The polymerization was well controlled as attested by the production of polymers with low dispersity (Đ < 1.26) and by the linear evolution of molecular weights with the quantity of initiator. Without 1-butanol, although MALDI-TOF analyses revealed cyclic PLA chains (actually formed in situ during MALDI-TOF analysis), linear PLA chains were formed as proven by ¹H NMR, viscosity measurement, and phosphitylation titration. This fast and "on demand" polymerization opens the way to biodegradable UV coatings.