Novel Polymer nanocomposites prepared through supercritical CO_2 processing: Structure and mechanical properties

摘要

Nano-clays, carbon nanotubes, and other nano-scale fillers can have a significant impact on the physical properties of polymers. The degree of enhancement in the properties depend largely on the degree of dispersion (or exfoliation) of the nanoscale fillers. Conventional approaches to achieving layer separation include chemical modification of the clay surface, and reaction polymerization of monomers mixed with clays. Even these approaches typically result in intercalated nanocomposites. Supercritical fluids (SCF) possess significantly reduced viscosities and increased difiusivities, in addition to enhancing the solubilities of polymers and nanofillers. Therefore, we are using supercritical carbon dioxide (scCO_2) to achieve clay-clay separation by manipulating the processing conditions, resulting in largely intercalated or exfoliated nanocomposites. The scCO_2 process appears to be economical, efficient, and environmentally friendly. The structure of these nanocomposites are investigated and confirmed with WAXD, TEM, SEM, and rheology.