Surface modified graphene/single-phase polyurethane elastomers with improved thermo-mechanical and dielectric properties

Abstract

We report an efficient, simple and fast method for graphene surface modification and its novel use for the fabrication of very soft, single-phase polyurethane (PU) nanocomposite elastomers. Content of the surface modified graphene (SMG) in PU was between 0.2 and 5wt%. FT-IR and thermogravimetric analysis indicated successful surface modification of graphene by 3-aminopropyltriethoxysilane while a large increase in the viscosity of the polyol blend with SMG content suggested its exfoliation down to six graphene layers, as observed by atomic force microscopy (AFM). The scanning electron microscopy and AFM of elastomers revealed strong SMG–PU interactions and good dispersion of SMG within the matrix, respectively. Consequently, we measured more than a two-fold increase in the tensile strength and storage modulus of SMG/PU elastomer at addition of 5wt% of SMG, compared with unfilled PU. An initial degradation temperature and the maximum rate of weight loss of PU with 5wt% SMG was upshifted by 10°C and 8°C, respectively, showing improved thermal stability of the matrix. Finally, an increased dielectric permittivity at 1Hz from 3.6 for unfilled PU up to 34.2 for PU elastomer with 5wt% SMG, in the glassy state, was observed by dielectric spectroscopy indicating energy storage capabilities of these nanocomposites.