A study of crystallisation of poly (ethylene oxide) and polypropylene on graphene surface

Crystallisation behaviour of poly (ethylene oxide) (PEO) and isotactic polypropylene (iPP) on graphene surface was investigated by means of polarized microscopy, wide angle X-ray diffraction (WAXD), and Raman techniques. Results indicated that graphene influences the crystallisation and crystal structure of iPP and PEO. WAXD peaks shifting toward lower diffraction angle, i.e. increase in d-pacing, was observed in both PEO and iPP crystallised on the surface of graphene. The change of d-spacing of both PEO and iPP could result from the compressive stress caused by graphene. A shift of 2D band in graphene was observed from Raman spectra. The Raman spectra indicated the big shift in the 2D band is due to the presence of stress induced strain in the polymer attached graphene. The residual stress was generated during crystallization of the polymers on the surface of graphene. Due to the interactions between the graphene and the polymers, the stress was transferred to the graphene which leads to a strain of the graphene. Raman spectra proved the presence of stress generated by the crystallization of the polymers on the surface of graphene.