Syndiotatic Polystyrene Aerogels with β, γ, and ε Crystalline Phases

The influence of thermal treatments and supercritical carbon dioxide extraction procedures on the crystal structure and morphology of sPS aerogels is investigated mainly by wide-angle X-ray diffraction and scanning electron microscopy. The use of supercritical CO2 extraction treatments allows the obtaining of high porosity aerogels with fibrillar morphology, not only exhibiting the nanoporous delta phase but also the dense gamma and beta crystalline phases. Moreover, a procedure to obtain high-porosity aerogels exhibiting the recently discovered nanoporous epsilon-form is described. Measurements of the sorption capacity of organic molecules from diluted aqueous solutions, for aerogels presenting different crystalline phases, clearly indicate that epsilon-form aerogels are the only ones suitable for detection and removal of long organic pollutants.