Interface mechanics of liquid crystal polymer nanocomposites with high concentrations of MWCNTs

Abstract

Compositing a liquid crystal polymer (LCP) with highly oriented multi-walled carbon nanotubes (MWCNTs) at non-dilute filler concentrations has attracted considerable attention due to its function as alignment layer as well as mechanical reinforcement. In this study, the structural and mechanical features of the LCP-MWCNT interface were investigated by all-atom molecular dynamics (MD) simulations. The results suggested that the MWCNT filler co-oriented with the liquid crystalline matrix enhances the crystallinity of the LCP molecules, especially in the interfacial area. The aromatic rings of the LCP components exhibited a repeating structural pattern because of the different equilibrium distances depending on the type of pi-pi stacking. The effect of the morphological change of LCPs in the interfacial region on the load transfer capability was also evaluated in terms of filler concentrations. In particular, tight coupling between the liquid crystal components and efficient load transfer to the outermost nanotube shell were first identified. These features account for the enhanced mechanical stiffness in the transverse loading direction with increasing volume fraction of the MWCNTs, as confirmed experimentally.