2D nanosheets have pushed forward the development of nanotechnology and materials science. We have explored the potential property enhancements of bioplastics by a combination of graphene oxide (GO) nanosheets and crystallization control with the goal of harnessing improved barrier and mechanical properties as well as the high thermal stabilities. We revealed that addition of GO nanosheets in the enantiomeric stereocomplex poly(lactic acid) (PLA) exclusively accelerated the stereocomplex (SCs) crystallization. No traces of the confinement effect was shown even when geometrical networks were generated at high GO loadings (0.1 and 0.5 wt%). In essence, both the basal planes and the curvy edges of GO were ready to provide enormous and active platforms to preferentially nucleate the neighboring stereocomplex chains, prompting the development of prevailing SCs during the isothermal melt crystallization, regardless of the temperature. By contrast, homo-crystallization was pronouncedly suppressed in the GO composites crystallized at 150 °C. More importantly, the nanosheets decorated with ordered PLA lamellae, in turn, contributed to great enhancement of barrier and mechanical properties and chemical resistance. For example, a distinct decrease of 98.5% in oxygen permeability coefficient was observed for the composite films containing 0.5 wt% GO (0.062 × 10–14 cm3 cm cm–2 s–1 Pa–1) compared to the control sample crystallized at 150 °C (4.214 × 10–14 cm3 cm cm–2 s–1 Pa–1). The performance distinction was accompanied by improved tensile strength (73.5 MPa) and elongation (13.6%), demonstrating an increase of 31.7% and 183.3% compared to the counterpart, respectively. Our findings provide a broader context to tune the function and property of PLA by crystallization, which helps to outline the roadmap for future development of high-performance polymeric composites.

Enhancing the function of graphene oxide nanosheets by crystallization control: Unexpected harvest of strength, ductility and thermal stability for poly(lactic acid) barrier films

251st National Meeting (2016)

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