Highly Enhanced Crystallization Kinetics of Poly(l-lactic acid) by Poly(ethylene glycol) Grafted Graphene Oxide Simultaneously as Heterogeneous Nucleation Agent and Chain Mobility Promoter

Nanofillers can act as effective heterogeneous nucleation agents for semicrystalline polymers; however, it never facilitates the crystal growth. In the current work, we proposed a facile strategy to enhance the crystallization kinetics of poly(l-lactic acid) (PLLA) by simultaneously accelerating the crystal nucleation and growth. Herein, we synthesized poly(ethylene glycol) (PEG) grafted graphene oxide (GO) (PEGgGO). Pronounced effects of PEGgGO on the crystalline morphology and crystallization rate of PLLA were explicitly clarified by direct morphological observation and quantitative crystallization kinetics analysis. The results manifested that, in contrast to the unmodified GO, PEGgGO desirably dispersed in PLLA and also preserved the high nucleation ability. More importantly, the flexible PEG chains on GO served as a chain mobility promoter and boosted the crystal growth rate of PLLA. Compared to the PLLA/GO nanocomposite containing 0.5 wt % GO, the nucleation density and crystal growth rate of the PL...