Improved crystallization capability and mechanical properties of poly( l ‐lactide) achieved by tailoring the grafted chain structure on graphene oxide

Abstract Interfacial interaction is crucial in modulating the microscopic morphology and macroscopic properties of composites. Generally, grafting polymer molecular chains on nanoparticles is an approach for enhancing the interfacial interaction, but the dependence of enhancement degree on molecular chain structure is not clear. In this work, nanosheets were obtained by grafting poly( d ‐lactide) (PDLA) and poly( l ‐lactide) (PLLA) molecular chains onto graphene oxide (GO), respectively, then PLLA‐based composites containing shallow loading (0.3 wt%) were obtained by melt‐blending. The findings indicated that grafting PDLA on the GO was more efficacious in enhancing the crystallization capability of PLLA, and the mechanism was primarily owing to stronger interfacial binding energy between the PLLA matrix and GO‐g‐PDLA, which was approximately 1.5 times that of the PLLA/GO‐g‐PLLA composite. Compared to the GO‐g‐PLLA nanosheets, GO‐g‐PDLA nanosheets exhibited apparent strengthening and toughening effect, and the composite sample exhibited significantly improved tensile strength and tensile ductility, with a respective increase of 21.5% and 52.2% compared with pure PLLA sample, respectively. Furthermore, all composite films (90 μm) maintain high transmittance close to 80%. This work further confirms that enhancing the interfacial binding energy by grafting PDLA molecular chains on nanoparticles is advantageous for enhancing both the crystallization and mechanical characteristics of the PLLA‐based composites. Highlights GO‐g‐PDLA and GO‐g‐PLLA were successfully synthesized. GO‐g‐PDLA showed more apparent nucleation effect in PLLA crystallization. GO‐g‐PDLA showed higher interfacial binding energy compared with GO‐g‐PLLA. Synchronously strengthening and toughening were achieved for PLLA/GO‐g‐PDLA.