Graphene oxide grafted with polydimethylsiloxane modified polyurethane

Abstract

In order to improve the dispersion of graphene oxide (GO) in polymers, we synthesized polyurethane (PU) chains with long polydimethylsiloxane (PDMS) chains as the "soft segment" and hexamethylene diisocyanate (HDI) as the "hard segment", then the PU chains were grafted onto GO. The results of compatibility in solvents and TEM images of composites indicated that the modified GO (GO-PU) would present two different shapes in non-polar and polar solvents (cocoonlike shape and stretched shape, respectively). The two shapes made it have a good dispersion in both non-polar and polar polymers, it was expected to be applied in both non-polar and polar polymer matrixes. This provided a method for covalent modification of GO.

Production and Characterization of Graphene Oxide Surfaces against Uropathogens

“…Among the tested GO/PDMS surfaces, the most substantial increase in average roughness was found from GO3/PDMS (Figure 2d) to GO5/PDMS (Figure 2e)-an approximate 61% increase in S a was observed from GO3/PDMS to GO5/PDMS, compared to an 11% increase from GO1/PDMS to GO3/PDMS. This supports the previously mentioned difficulty of uniformly dispersing GO in non-polar polymers [64], especially for higher GO concentrations. Overall, these results corroborate the findings from the SEM analysis.…”

“…The three GO-based surfaces exhibited greater hydrophobicity than PDMS and GNP/PDMS, that is, lower ΔG values than those of PDMS and GNP/PDMS. This suggests that the interactions between GO nanosheets [63] are stronger than those with water [64]. Furthermore, the degree of surface hydrophobicity slightly increased with the increment of GO loading.…”

“…It was also possible to observe that with an increase of GO loading from 1 to 5 wt.%, the number of visible clusters on the surfaces was greater. This is a consequence of the increment in the concentration of GO, which makes the uniform dispersion of this nanomaterial progressively more challenging in non-polar polymers, such as PDMS [64]. Furthermore, for the same loading of the carbon material (5 wt.%), SEM images suggest that there was a better dispersion of GNP (Figure 1b) than GO (Figure 1e) into the PDMS matrix.…”

“…Furthermore, for the same loading of the carbon material (5 wt.%), SEM images suggest that there was a better dispersion of GNP (Figure 1b) than GO (Figure 1e) into the PDMS matrix. This is probably a result of the oxygen-containing functional groups that graphene acquires from the oxidation process of turning graphite into GO, which enable attractive interactions between GO nanosheets, namely strong van der Waals forces, promoting the observed clustering behavior [64]. The surface roughness was determined by profilometry analysis (Figure 2).…”