Abstract 9871894, Schadler/RPI Recent work has shown that the modulus, strain to failure, and strength of polymer composites can be increased simultaneously with nanosized particle filler. This is not observed in micron sized filled systems. This proposal has dual objectives: 1) to create and investigate novel nanofiller/polymer composites for engineering application sand 2) to develop a fundamental understanding of their structure-property relationships through understanding the effects of particle dispersion, particle structure and surface chemistry, and polymer chain stiffness on the size of the bound polymer layer and on the mechanical properties. Nanoparticle fillers will be synthesized using the gas condensation method. A wide range of metal, ceramic, and composite nanoparticles will be synthesized in the size (diameter) range of 5-50 nm by this method. In addition, the nanoparticles can be coated to modify their surfaces. Nanofiller/polymer composites will be prepared using elastomers, thermoplastics, and thermosets. Microstructural characterization will be done using a variety of techniques such as TEM, SEM and X-ray diffraction. The effect of the nanoparticle on the surrounding polymer region will be used to confirm the NMR observations on a more macroscopic scale. Micro-Raman spectroscopy will be used to gain an understanding of the micro(nano)mechanical behavior. The measured mechanical properties of these new composites will be compared with those of existing fiber and particle filled composites. This research is relevant to fabrication of high modulus, high strength polymer composites. Research on the fabrication and testing of nanocomposites will complement an educational initiative at RPI on nanomaterials. This project results from a proposal submitted in response to NSF 98-20, Partnership in Nanotechnology: Synthesis, Processing, and Utilization of Functional Nanostructures (FNS).