In situ intercalation polymerization approach to polyamide-6/graphite nanoflakes for enhanced thermal conductivity

Traditional polymer composites generally present limited thermal conductivity (TC) even highly loaded with highly thermally conductive fillers due to the lack of large interfacial thermal resistance between the fillers and the surrounding polymers. In this work, polyamide-6/graphite nanoflakes (PA6/GnF) composites with high TC can be obtained through a one-step in situ intercalation polymerization. The caprolactam onium ion (CL) catalysted by 6-aminocaproic acid can effectively intercalate into the interlayer of expanded graphite (EG) and lead to the separation of EG into GnF after in situ polymerization. Thereafter the homogeneous dispersions of GnF with ordered arrangement and strong interfacial interactions between PA6 and GnF can be formed within the PA6/GnF composites, which can favor the formation of the consecutive thermal conductive pathways or networks at a relatively low EG loading. The obtained composites, at only EG loading of 12 wt%, exhibit a high TC (2.49 W/mK), corresponding to an enhancement of 678% compared to that of neat PA6. This strategy offers new insights into the fabrication of graphene based composites, and provides a straightforward and highly industrializable process for fabrication of high-performance GnF-based thermally conductive composites. (C) 2017 Elsevier Ltd. All rights reserved.