Interface nanoengineering of a core-shell structured biobased fire retardant for fire-retarding polylactide with enhanced toughness and UV protection

In this work, we found a very effective method to adjust the polarity of the fillers to promote its good dispersion in matrix by using an organic-solvent-free assembling strategy. With the coating of polyethylenimine-decorated graphene oxide (GO-PEI), the as-prepared biobased core-shell graphene oxide hybrid (BCSGOH) can distribute more homogeneously in the polylactide (PLA) matrix, compared with the bio-derived core-shell flame retardant (CSFR) with higher polarity. The polarity analysis of BCSGOH, CSFR and PLA indicated that the polarity of BCSGOH had a better match with that of PLA, and the interfacial tension (0.8 mN/m) between BCSGOH and PLA was much lower than that (12.0 mN/m) between CSFR and PLA. Consequently, the better flame retardancy, impact toughness and UV-shielding properties of PLA/BCSGOH composites were achieved. 6 wt% of BCSGOH endowed PLA with the best comprehensive properties, such as the UL94 V-0 rating, the limiting oxygen index (LOI) of 30.0%, and notched impact strength of 12.38 kJ/m(2). Hence, this work offers a conducive, facile and green strategy to create high-performance fire-safe bioplastics.

Automated summary

In this study, an effective method was found to adjust the polarity of fillers to improve their dispersion in a matrix. By coating polyethylenimine-decorated graphene oxide, the biobased core-shell graphene oxide hybrid achieved a more uniform distribution in the polylactide matrix and enhanced flame retardancy, impact toughness, and UV-shielding properties of the composite material.