Electrically-Conductive Polyketone Nanocomposites Based on Reduced Graphene Oxide.

Esteban Alejandro Araya-Hermosilla,Andrea Pucci,Marco Carlotti,Virgilio Mattoli,Francesco Picchioni

doi:10.3390/polym12040923

Abstract

In this work, we investigated the functionalization of polyketone 30 (PK30) with glycyl-glycine (Gly-Gly) via the Paal–Knorr reaction with the aim of homogenously dispersing two types of reduced graphene oxide (rGO, i.e., lrGO and hrGO, the former characterized by a lower degree of reduction in comparison to the latter) by non-covalent interactions. The functional PK30-Gly-Gly polymer was effective in preparing composites with homogeneously distributed rGO characterized by an effective percolation threshold at 5 wt. %. All the composites showed a typical semiconductive behavior and stable electrical response after several heating/cooling cycles from 30 to 115 °C. Composites made by hrGO displayed the same resistive behaviour even if flanked by a considerable improvement on conductivity, in agreement with the more reduced rGO content. Interestingly, no permanent percolative network was shown by the composite with 4 wt. % of lrGO at temperatures higher than 45 °C. This material can be used as an ON–OFF temperature sensor and could find interesting applications as sensing material in soft robotics applications.

Highlights

Graphene has called high attention thanks to its excellent mechanical properties, thermal conductivity, and electronic transport properties [1,2,3,4]
The electric properties of GO can be recovered by reduction treatments (producing reduced graphene oxide), which partially restores the graphitic network of sp2 carbons [13,14]
Aliphatic polyketones composed by ethylene, propylene, and CO were synthesized according to a reported procedure [44,45] yielding a polyketone with the aliphatic part comprised of 30 mol%

Summary

Introduction

Graphene has called high attention thanks to its excellent mechanical properties, thermal conductivity, and electronic transport properties [1,2,3,4]. Graphene oxide (GO) has replaced graphene in many applications due to low cost of production and dispersibility in water and polar organic solvents [6,7] As graphene, it possesses a 2D structure but some of the carbons atoms lost the sp character being involved in the covalent linkage with hydroxyl, epoxide, and carbonyl groups generated during the oxidation of the graphene layer [8,9,10]. The residual functional groups remained in the rGO structure make its dispersion easier in organic solvents [15] and increase the Polymers 2020, 12, 923; doi:10.3390/polym12040923 www.mdpi.com/journal/polymers preparation of functional polymer nanocomposites [18,19,20] where rGO can provide enhanced electrical and mechanical properties [21,22,23,24,25] In this sense, these materials have found a variety of applications such as supercapacitor electrodes [26], chemical sensor [27], and antibacterial scaffolds [28]. Despite the better results when compared to graphene, obtaining good dispersions of rGO into the polymer matrices is still challenging: the absence of highly interacting functional groups

Methods

Findings

Discussion

Conclusion