A Functionalized Cyclic Lactide Monomer for Synthesis of Water-Soluble Poly(Lactic Acid) and Amphiphilic Diblock Poly(Lactic Acid).

Biodegradable and bioabsorbable poly(lactic acid)s are one of the most important biomedical materials. However, it is difficult to introduce the functional groups into poly(lactic acid)s in order to improve their hydrophilicity and degradation rate. Here the authors describe the synthesis of functionalized cyclic lactide monomer 3,6-bis(benzyloxymethyl)-1,4-dioxane-2,5-dione (BnLA) using an advanced synthetic route. Water-soluble hydroxyl-functionalized homopoly(lactic acid) (P(OH)LA) is synthesized via ring-opening polymerization (ROP) of BnLA, followed by a hydrogenolytic deprotection reaction. Amphiphilic diblock poly(lactic acid) (P(OH)LA-PLA) is synthesized via ROP of DL-lactide using PBnLA as an initiator, followed by a hydrogenolytic deprotection reaction. P(OH)LA-PLA is able to form polymeric micelles with the diameter of sub-100 nm.