Organometallic-Catalyzed Synthesis of High Molecular Weight Poly-(L-Lactic Acid) with a Covalently Attached Imidazolium Salt: Performance-Enhanced Reduced Graphene Oxide-PLLA Biomaterials

Herein, we report about 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 initiator, the organometallic Zn(C6F5)2toluene complex polymerized L-lactide into high molecular weight PLLA-IS (Mn 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 obtained, reaching 148% and 105% for the loss and storage moduli, respectively. Besides, the composite PLLA-IS/rGO-1% inhibited the growth of fungal biofilms, including C. tropicalis (43%) and C. albicans (34%). Altogether, these materials have the properties for novel applications, including those of biomaterials.