Segregated nanomaterial networks, obtained through drying of colloidal co-dispersions of nanoparticle filler and polymer matrix particles, are a promising route to functional materials with low loadings of filler. The loading level at which a system-scale interconnected nanomaterial network is formed is known as the percolation threshold, and may be manipulated through choice of the matrix particles as well as the filler particles in terms of their packing efficiencies and aspect ratios. Lowering the loading required to achieve a functional composite structure is critical to maximizing the benefit of filler addition while avoiding any detrimental impacts on the properties of the matrix material. Graphene oxide is a prototypical water-dispersible monolayer filler, which may be processed into segregated networks in combination with aqueous polymer latex dispersions as the matrix polymer, but requires reduction to achieve any functionality (i.e. electrical conduction) beyond mechanical reinforcement. In this study we observe highly-conductive yet mechanically-robust networks via in situ reduction of graphene oxide within a polymer latex. A sharp percolative transition of the composite from insulating to conducting, as well as electron microscopy and Kelvin probe force microscopy of the microstructure, indicates explosive percolative growth of the conducting network following aromatisation of the matrix polymer. Further, the kinetics of the reduction process show that the graphene oxide reduction is the driver for the modifications observed. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy indicates the production of conjugated carbon with phenolic functionalities, which is consistent with crosslinking agents which have been demonstrated to realize high reduced graphene oxide network conductivities at low loadings in similar systems.

Explosive percolation produces highly-conductive polymer nanocomposites

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.