The interphase properties of the reinforcing carbon nanotubes and carbon monofilaments in polymer matrix composites (PMCs) have not been given enough attention in the literature. Three-phase composite specimens were fabricated using carbon nanotube particles, carbon nanotube membranes, carbon fibers, and epoxy resin materials. The advanced Atomic Force Microscopy based Peak Force Quantitative Nanomechanics Mapping technique was used to investigate the interphase properties at sub-micron-and nano-scales. So far, the results show different interphase morphology between polymer/carbon fibers and polymer/CNT agglomerates in PMCs and polymer nanocomposites. BP is heterogeneous at the nanoscale, depending on resin impregnation quality into BP's porous structure. An interphase layer with a thickness of 13-25nm between epoxy and epoxy/CNT agglomerates was observed in three-phase CNT particle and CNT membranes Polymer matrix composites, higher than ~10-13nm interphase between epoxy and carbon fiber monofilament.