Facile Synthesis of Fluorine-Substituted Polylactides and Their Amphiphilic Block Copolymers

We report facile synthesis of 3-trifluoromethyl-6-methyl-1,4-dioxane-2,5-dione and ring opening polymerization of the fluoro-lactide monomer to prepare polylactides composed of  trifluoromethyl and methyl pendent groups on each repeat unit (FPLA). Molecular weights of the prepared polymers correlated well with the initial molar ratio of monomer to initiator, and were found to range from 6.6 to 22.5 kDa as determined by 1H NMR spectroscopy. GPC analysis revealed an Mn of up to 16.5 kDa. 1H, 13C, and 19F NMR spectroscopy were consistent with the structures of the lactide monomer isomers, and 1H NMR analysis was consistent with polymer backbones of alternating trifluoromethyl- and methyl-substituted lactate constituents. Glass transition temperature (Tg) and decomposition temperature (Td) of the new FPLA were found to be 39 °C and 225 °C by DSC and TGA, respectively. Additionally, we prepared amphiphilic block copolymers of FPLA and polyethylene glycol (PEG). Specifically, FPLA-b-PEG diblocks and FPLA-PEG-FPLA triblocks were synthesized by using PEG monomethyl ether (mPEG) or PEG as alcohol initiators, respectively. We observed the formation of vesicles or worm-like micelles from the particles of FPLA-PEG-FPLA in dilute aqueous solution by transmission electron microscopy (TEM), suggesting potential applications for drug delivery.

Read the full article at: https://pubs.acs.org/doi/10.1021/acs.macromol.7b02531