Graphene nanoplatelets (GnP) consist of a few layers of graphene with thicknesses in the nanometer range. GnP is considered a multifunctional nanomaterial since it possesses excellent mechanical, electrical and thermal properties and as a result of its 2D structure, it offers the possibility of improving the barrier properties of a polymer matrix by reducing the permeability of small molecules through the polymer matrix. The aromatic planar basal surface of GnP consisting of carbon in the sp2 state is inert and the carbon atoms at the GnP edges are the few sites at which functional groups can be added to GnP. When GnP is treated with strong acids, graphene oxide (GO) is formed. The carbon atoms are changed from sp2 to sp3 bonding and the basal plane surface has a large population of oxygen groups which change the surface from hydrophobic to hydrophilic. The GO has the potential to act as a coupling agent to improve the interfacial interaction between GnP and the polymer matrix. Besides adding GnP to a polymer to form a multifunctional polymer composite, the GnP can be fabricated into thin 'paper' electrodes by vacuum filtration of a GnP suspension. This GnP thin film has in-plane electrical conductivity similar to metals and when coated with an insulating polymer layer can function as an electrode in an electrostatic actuator. This dissertation investigates the interaction of GnP with polymer matrices, modifying the surface chemistry to improve the interfacial interaction between filler and matrix, and exploring new applications for multifunctional GnP-polymer composites.The dispersion of GnP into a thermoplastic polyurethane (TPU) through melt blending has been investigated. The dispersion and alignment of GnP plays a key role in attaining the multifunctional properties of the composite. 25wt% GnP was incorporated into TPU through an extrusion process, wherein the dispersion and alignment of GnP was controlled by the film extrusion speed. The effect of three film extrusion speeds of 2, 3 and 5 ft/min on the dispersion and alignment of GnP were investigated. The optimum extrusion conditions gave 350% improvement in through-plane thermal conductivity; 75% reduction in oxygen permeability; and the tensile modulus and strength increased by 950% and 470% respectively.Graphene oxide (GO) was selected as a possible modifier to improve the interaction between GnP and an epoxy matrix. The rich oxygen based functional groups on the GO surface could function as reaction sites for chemical bonding directly or sites for adding other chemical groups such as diamines or epoxy. GO and GnP were sonicated together in a water phase forming a GO-GnP complex, followed by treatment with two different diamines ( (p-phenylenediamine (PPDA) and Jeffamine D2000) with different chain lengths. The functionalized GO-GnP complex was added to the GnP-epoxy composite at a 0.86wt% loading. An increase in tensile modulus of 603030% was measured as a result.The GnP was also investigated as a thin 'paper' electrode fabricated through vacuum filtration of a GnP suspension. GnP electrodes were fabricated from the compressed GnP paper and then coated on both sides with a thin epoxy layer. An electrostatic actuator was constructed from two parallel-aligned composite GnP paper electrodes fixed at the anode of the high power supply and with the cathode connected to the ground. The two composite electrodes would separate at the free end when a voltage was applied. The actuating performance was shown to be improved based on either increasing the surface area of electrode or enhancing the relative permittivity of the insulating layer between two electrodes.
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