Guohu Guan

Surface functionalization of graphene oxide (GO) by grafting polymer chains to its surface is achieved by direct use of GO as the initiator for polymerization of N-vinylpyrrolidone (NVP). The functionalized GO can be readily dispersed in a variety of solvents which facilitates graphene processing for a wide range of applications. Fourier-transform infrared, X-ray powder diffraction and transmission electron microscopy investigations show that poly(vinylpyrrolidone) is grafted onto the GO surface, and X-ray photoelectron spectroscopy, elemental analysis and conductivity measurements suggest modest reduction of the functionalized GO during the surface-initialized polymerization. Both electron spin resonance and ¹³C-NMR spectra indicate that breakage of weak bonds at the defects on the GO surface initialized the radical polymerization of NVP.

An efficient method was developed for the in situ synthesis of poly(ethylene terephthalate)/graphene composites by using a polycondensation catalyst supported on graphite oxide (GO-Cat). The GO-Cat was prepared by loading a catalyst of titanium dioxide/silicon dioxide nanoparticles on organofunctionalized graphene oxide sheets, and was characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. During the in situpolycondensation process, nanoscale dispersion and thermal reduction of graphene oxide were achieved simultaneously. The composites obtained exhibited a rather low electrical percolation threshold due to the homogeneous dispersion of graphene sheets within the matrix and the effective reduction of graphene oxide in the polycondensation process.