Epoxy modified with polymer-grafted GO: Role of bimodal functionalization in formation of ordered structures

The modification of epoxy with polymer-grafted graphene oxide (GO) is a radical alternative to mere combination of GO with a polymeric modifier. Here, this aspect is revealed for the case of bimodal grafting of GO with hydrophobic polybutadiene and hydrophilic polyoxypropylene or polyethylene glycol utilizing grafting-to approach to link different chains in the plane and edge area of GO. The results indicate fair ability of bimodally grafted GO to form ordered lamellar structures in epoxy. However, these structures show larger distance between less aligned GO plates in contrast to tightly aligned GO arrangement in case of single grafting. This is enabled by repulsive interactions between dissimilar chains. Such a structure with higher mobility of grafted chains has favorable effect on mechanical performance of epoxy. The effect of chain type and geometry of grafting is highlighted as well. Important finding is promotion of lamellar structure formation also by grafted low-m. w. compounds.