Effect of Polymer Structure on Precursor Diffusion and Particle Formation in Polymer Matrix Nanocomposites

Abstract

Palladium nanoparticles were synthesized in a semi-crystalline poly[tetrafluoroethylene-co-(perfluoropropyl vinyl ether)] matrix using a chemical infusion technique where a chemical precursor is vaporized and diffused into the polymer matrix. Once in the matrix, the precursor is made to decompose resulting in nanoparticle formation. The effect of polymer structure on precursor diffusion was investigated by comparing the diffusion behavior of the precursor molecules in the as-received polymer as well as in a heat-treated polymer matrix. Results from the diffusivity measurements were interpreted using a free volume model to gain a physical and conceptual understanding of precursor diffusion in fluoropolymers. In addition, transmission electron microscopy analysis was performed on the polymer matrix nanocomposites, and significant differences in particle size and spatial distributions were found between nanocomposites synthesized using as-received and heat-treated polymer matrices. Both precursor diffusivity and particle formation changed as a result of modifications to the polymer matrix suggesting that the particle size and spatial distribution are determined by the structure and morphology of the polymer matrix and are likely linked to the free volume of the polymer.