Many recent papers have highlighted how the interface between a nanoparticle and the surrounding polymer chains can induce changes in the matrix polymer to create better than expected bulk properties of the nanocomposite. This region of modified polymer near the nanoparticle is termed the interphase and is comparable to observed changes in thin polymer films due to the nanoscale interparticle spacing. While most research in carbon-based nanoparticles has focused on nanotubes, two other geometries exist with similar surface areas (~1200 m2/g). We prepared PMMA nanocomposites using zero, one and two-dimensional carbon-based nanoparticles (C60, SWCNT, and Thermally Expanded Graphite Oxide) which have been functionalized with the same surface groups. We have investigated how the interphase is affected by the geometry of the nanoparticle using thermal, mechanical, and electrical experiments.