Design of high-performance poly(l-lactide)/elastomer blends through anchoring carbon nanotubes at the interface with the aid of stereocomplex crystallization

Abstract

Selective localization of nanoparticles at the interface of immiscible polymer blends has been witnessed as an efficient method to improve blend properties and even provide some added functionalities. Nevertheless, it is still a great challenge to achieve thermodynamically stable interface-localization of the nanoparticles mainly due to their low interfacial stabilities as well as high transfer speeds between the blend phases, especially for those with high aspect ratios. In this work, taking poly(l-lactide)/poly(d-lactide) grafted ethylene-acrylic ester copolymer/multi-walled carbon nanotubes (PLLA/EGD/MWCNTs) ternary composite as an example, we describe a new and facile strategy to address this challenge via anchoring high-aspect-ratio MWCNTs at the interface of PLLA/EGD blends using interface-localized stereocomplex (SC) crystallites as anchoring agents. During melt mixing of EGD with PLLA/MWCNTs mixture, such SC crystallites can be rapidly formed at the blend interface to prevent MWCNTs transferring from the thermodynamically unfavorable PLLA matrix into favorable EGD phase as physical barriers, and meanwhile some of these transferring MWCNTs could serve as nucleating agents to induce SC crystallization on their surfaces. As a result, many MWCNTs are firmly anchored at the blend interface by these SC crystallites. The anchored MWCNTs can not only function as effective interfacial enhancers to remarkably enhance interfacial strength and resulting impact toughness of PLLA/EGD blends but also enable the formation of electrical conductive pathway in the network-like PLLA/EGD blends at a much lower percolation threshold. This wok could offer a promising opportunity for preparing high-performance and multifunctional PLLA-based composites through controlling particle localization at the interface of immiscible PLLA blends with the aid of SC crystallization.