Photochemically Generated Polyacrylonitrile−Silica Nanocomposites:  Optimized Fabrication and Characterization

Nanocomposites of polyacrylonitrile in a porous silica matrix (Vycor) were generated by the photopolymerization of acrylonitrile inside the nanopores of the matrix. The amount of polymer incorporated could be controlled by photoinititator concentration and by the irradiation time. Studies of the changes in pore volume and surface area of the matrix as a function of polymer loading lead to a model for pore filling in which the polymer forms plugs across the diameter of the pore, leaving closed void areas behind. The microenvironment of the polymer phase as related to the model for pore filling is investigated by the use of fluorescent probe molecules. Finally, the crystallinity and relative molecular weight distribution of the nanophase polyacrylonitrile are also reported.