(543h) Align Graphene Layers Using Polymer Interfacial Interactions

Inter- and intra-molecular interactions such as coiling or polymer chain entanglements can generate stresses or strains of different degrees. These forces or displacement as a result of polymeric diffusion or stretching can be used for nanomaterial synthesis. For example, the mass production of high-quality graphene has been challenging, especially when the in-plane morphologies of these exfoliated sheets need to be controlled in optics, electronics or composites. In addition, as compared to their allotropes of carbon nanotubes or fullerene, graphene exhibits higher mechanical robustness of modulus of ~1 TPa and strength of ~130 GPa. However, these intrinsic properties have not been achieved in polymeric composites due to the complexity of graphene conformations within the molecules. This research aimed at achieving aligned and exfoliated graphene from stacked graphite layers using interfacial interactions among different phases in composites. The polymer-graphene interactions going beyond the graphene-graphene Van der Waals forces will lead to the aligned graphene layers laminated between polymer channels. Our design of multi-phase spinneret allowed the fabrication of coaxial polymer/graphene/polymer composite fibers. A stepwise drawing of the multiphase samples produced fibers with different dimensions and molecular morphologies; more importantly, the graphene will be exfoliated and aligned due to the shear stress by the comparative movements of different polymer channels. Significant mechanical and electrical properties were induced due to the graphene layer reductions and orientations. X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Raman, and, thermogravimetric analysis (TGA) were used to characterize the material structure and properties.