Enhanced Thermal Conductivity of Polyamide-Based Nanocomposites Containing Graphene Oxide Sheets Decorated with Compatible Polymer Brushes.

Łukasz Łątka,Szczepan Zapotoczny,Kamil Goc,Czesław Kapusta

doi:10.3390/ma14040751

Abstract

Polyamide-based nanocomposites containing graphene platelets decorated with poly(acrylamide) brushes were prepared and characterized. The brushes were grafted from the surface of graphene oxide (GO), a thermally conductive additive, using atom transfer radical polymerization, which led to the formation of the platelets coated with covalently tethered polymer layers (GO_PAAM), accounting for ca. 31% of the total mass. Polyamide-6 (PA6) nanocomposites containing 1% of GO_PAAM were formed by extrusion followed by injection molding. The thermal conductivity of the nanocomposite was 54% higher than that of PA6 even for such a low content of GO. The result was assigned to strong interfacial interactions between the brushes and PA6 matrix related to hydrogen bonding. Control nanocomposites containing similarly prepared GO decorated with other polymer brushes that are not able to form hydrogen bonds with PA6 revealed no enhancement of the conductivity. Importantly, the nanocomposite containing GO_PAAM also demonstrated larger tensile strength without deteriorating the elongation at break value, which was significantly decreased for the other coated platelets. The proposed approach enhances the interfacial interactions thanks to the covalent tethering of dense polymer brushes on 2D fillers and may be used to improve thermal properties of other polymer-based nanocomposites with simultaneous enhancement of their mechanical properties.

Highlights

Published: 5 February 2021The discovery and isolation of single graphene flakes have initiated tremendous interest in this material for both fundamental studies and industrial applications
Polyamide 6 (PA6) is an engineering thermoplastic material commonly used as a replacement of metals in various applications due to its excellent performance-cost ratio
The value of thermal conductivity of PA6 was found to increase by 54%, reaching

Summary

Introduction

The discovery and isolation of single graphene flakes have initiated tremendous interest in this material for both fundamental studies and industrial applications. Research and development studies on graphene-based materials have been carried out on a large scale, but the number of commercial applications is rather limited [1,2]. Due to their high strength as well as electrical and thermal conductivity, are natural candidates for plastics additives. The main issues that need to be addressed to introduce graphenebased material into the market in the form of plastic nanoadditives are the high production costs of graphene and problems with its homogeneous dispersion in the polymer matrix [3]. The interfacial properties between the polymer matrix and the nanoadditive significantly influence the final properties of the nanocomposite and homogeneous distribution of fillers [4,5].

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Conclusion