Modification of MWNTs by the combination of Li-TFSI and MAPP: Novel strategy to high performance PP/MWNTs nanocomposites

Abstract

Polypropylene (PP)/multi-walled carbon nanotubes (MWNTs) nanocomposites with excellent toughness and ductility pose significant challenges because of the severe aggregation of MWNTs in non-polar PP matrix due to the incompatibility. In this work, lithium bis(trifloromethanesulfonyl) imide (Li-TFSI) and maleic anhydride grafted polypropylene (MAPP) have been simultaneously introduced to modify MWNTs for the homogenous dispersion in PP matrix. The surface of MWNTs has strong “π-cation” interactions with the Li+ ions of Li-TFSI. At the same time, Li-TFSI can promote the ring-opening of the maleic anhydride and form coordination with the newly formed carboxylate. Therefore, the combination of Li-TFSI/MAPP enhanced the compatibility between PP and MWNTs. The Li-TFSI/MAPP modified MWNTs can be dispersed uniformly in the polypropylene. The elongation at break and the toughness of the nanocomposites with the 3 wt % modified MWNTs are 800% and 26 kJ/m2, respectively. The values are significantly higher than those of the samples (200% and 22 kJ/m2) at the same MWNTs loading. The strategy paves new possibility to fabricate high performance PP nanocomposites.