Composition dependence in surface properties of poly(lactic acid)/graphene/carbon nanotube composites

The surface properties of nanofillers and surface/interfacial interactions between fillers and matrix play crucial roles in the control of the properties of composites, especially considering hybrid materials used in biomedical, electronic and energy applications. In the present work, we investigate the surface properties of mono-filler and bi-filler composites of poly (lactic acid) (PLA) with graphene nanoplatelets (GNP) and multi-walled carbon nanotubes (MWCNTs) prepared by melt extrusion method. Zeta potential, contact angle (surface energy), Raman spectroscopy, and atomic force microscopy were used to evaluate the interaction between PLA matrix, GNP and MWCNTs particles, and also to characterize filler-polymer composite properties at the surfaces of the film. The effect of filler loading in the GNP/PLA and GNP/MWCNT/PLA composite films surface properties was investigated using surface Zeta potential by streaming and Contact angle measurements. The results suggest that the surface characteristics of the composite film may be synergistically tuned by incorporation of GNPs and MWCNTs with controlling the filler contents and filler combinations.