Synthetic Pathways Enables the Design of Functionalized Poly(lactic acid) with Pendant Mercapto Groups

Functionalized poly(lactic acid) having sulfur-protected groups along the chain have been synthesized with the ultimate aim to obtain materials for reversible and degradable self-assembly systems. The first step in the synthesis was the preparation of hydroxy-(4-methyl-phenylsulfanyl)- propionic acid and hydroxy-(tritylsulfanyl)-propionic acid. These sulfur-functionalized hydroxy acids were subsequently used as comonomers in the condensation polymerization of lactic acid producing functionalized polyesters with thio-protected groups along the chain. The ratio of functionalized hydroxyl-acid in the copolymer was determined by the feed ratio. The polyesters obtained were amorphous and size exclusion chromatography analysis showed a monomodal distribution. When treated with iodine, the polyesters chains bearing the tritylsulfanyl side groups assembled with the formation of SAS bridges and the molecular weight increased accordingly.Functionalized poly(lactic acid) having sulfur-protected groups along the chain have been synthesized with the ultimate aim to obtain materials for reversible and degradable self-assembly systems. The first step in the synthesis was the preparation of hydroxy-(4-methyl-phenylsulfanyl)- propionic acid and hydroxy-(tritylsulfanyl)-propionic acid. These sulfur-functionalized hydroxy acids were subsequently used as comonomers in the condensation polymerization of lactic acid producing functionalized polyesters with thio-protected groups along the chain. The ratio of functionalized hydroxyl-acid in the copolymer was determined by the feed ratio. The polyesters obtained were amorphous and size exclusion chromatography analysis showed a monomodal distribution. When treated with iodine, the polyesters chains bearing the tritylsulfanyl side groups assembled with the formation of SAS bridges and the molecular weight increased accordingly.