Organometal-catalyzed synthesis of high molecular weight poly-(l-lactic acid) with a covalently attached imidazolium salt: performance-enhanced reduced graphene oxide–PLLA biomaterials

Abstract

Herein, we report on the synthesis of imidazolium salt end-functionalized PLLA (PLLA-IS) and its application in the preparation of reduced graphene oxide–PLLA composites. When applying the imidazolium salt 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate as the initiator, the organometallic Zn(C₆F₅)₂toluene complex polymerized L-lactide into high molecular weight PLLA-IS (M_n up to 56k). The presence of this imidazolium functionality enhanced the PLLA−reduced graphene oxide interaction, which promoted a homogenous dispersion of this filler when applying a solvent casting procedure. Significant improvements in the mechanical properties were achieved, reaching 148% and 105% for the loss and storage moduli, respectively. Besides, the PLLA-IS/rGO-1% composite inhibited the growth of fungal biofilms, including C. tropicalis (43%) and C. albicans (34%). Altogether, these materials exhibit properties for novel applications, including as biomaterials.