Graphene oxide-based silsesquioxane-crosslinked networks – synthesis and rheological behavior

Abstract

Click reaction between octa(3-azidopropyl)polyhedral oligomeric silsesquioxane (POSS–(N₃)₈) and heavily alkyne-decorated graphene oxide (GO) has led to crosslinking POSS with GO. Introducing POSS to GO and reduction of GO sheets by sodium ascorbate during click reaction has led to a hydrophobic and well organically dispersible material. Hydrophobic reduced graphene oxide crosslinked with polyhedral oligomeric silsesquioxanes (rGO–POSS) network showed high solubility in various organic solvents. GO, rGO, and rGO–POSS were used as fillers for fabricating polydimethylsiloxane nanocomposites for rheological investigations. While the larger GO-sheets led to a surprisingly low rheological percolation threshold, the significantly smaller rGO–POSS filled systems showed almost the same percolation threshold as GO-filled systems when only the graphenic part of the nanocomposites was considered. rGO-filled composites, which have the same low hydrophobicity and relatively small size as the rGO–POSS fillers, show a significantly higher percolation threshold, which is attributed to partial restacking of these fillers.