Abstract
We studied certain kinds of diepoxy monomers, with so-called `mesogens'- molecular groups that cause self-ordering - and cured them with appropriate curing agents. Their thermal conductivities were up to 5 times higher than those of conventional epoxy resins. We believe that the mesogens formed nanoscopic high-order structures and the structures formed mezoscopic structures, which were covalently bound together, suppressing phonon scattering. Such resin system is therefore considered to be a kind of polymer-polymer composite with controlled nanostructures. We confirmed the existence of crystal-like structures in the epoxy resins directly by transmission electron microscope (TEM) observation. We also observed mezoscopic structures in the resins with an atomic force microscope (AFM). The results suggest a novel method to improve the thermal conductivities of insulating resins themselves by controlling the nanoscopic high-order structures.
Subsequently, laminates were prepared with the developed resin composite consisting of a kind of epoxy resins with mesogens and ceramic fillers, and tested as a part of a feasibility study. The thermal conductivities of the test pieces were more than 10 times that of commercial FR-4 laminates. This result shows that controlling the nanoscopic high-order structure of the resins is effective in improving the thermal conductivity of resin composites, and the heat dissipation of electric devices as well.
