Photodegradation of dispersants in colloidal suspensions of pristine graphene.

We demonstrate that UV degradation can remove polymeric dispersants from the surface of colloidal pristine graphene. In particular, we investigated the irradiation of polyvinylpyrrolidone (PVP)-dispersed graphene in water; this polymer has been established as a versatile nanosheet dispersant for a range of solvents, and it undergoes photo-oxidative degradation when exposed to UV light. We find that the molecular weight of PVP decreases with irradiation time and subsequently desorbs from the graphene surface.

Liquid phase exfoliation and crumpling of inorganic nanosheets.

Here we demonstrate through experiment and simulation the polymer-assisted dispersion of inorganic 2D layered nanomaterials such as boron nitride nanosheets (BNNSs), molybdenum disulfide nanosheets (MoS2), and tungsten disulfide nanosheets (WS2), and we show that spray drying can be used to alter such nanosheets into a crumpled morphology. Our data indicate that polyvinylpyrrolidone (PVP) can act as a dispersant for the inorganic 2D layered nanomaterials in water and a range of organic solvents; the effectiveness of our dispersion process was characterized by UV-vis spectroscopy, microscopy and dynamic light scattering. Molecular dynamics simulations confirm that PVP readily physisorbs to BNNS surfaces.