Ultra-high dispersion of graphene in polymer composite via solvent freefabrication and functionalization

The drying process of graphene-polymer composites fabricated by solution-processingfor excellent dispersion is time consuming and suffers from a restacking problem.Here, we have developed an innovative method to fabricate polymer compositeswith well dispersed graphene particles in the matrix resin by using solventfree powder mixing and in-situ polymerization of a low viscosity oligomerresin. We also prepared composites filled with up to 20 wt% of grapheneparticles by the solvent free process while maintaining a high degree of dispersion.The electrical conductivity of the composite, one of the most significantproperties affected by the dispersion, was consistent with the theoreticallyobtained effective electrical conductivity based on the mean field micromechanicalanalysis with the Mori-Tanaka model assuming ideal dispersion. It can be confirmedby looking at the statistical results of the filler-to-filler distance obtainedfrom the digital processing of the fracture surface images that the variousoxygenated functional groups of graphene oxide can help improve the dispersionof the filler and that the introduction of large phenyl groups to the graphenebasal plane has a positive effect on the dispersion.