Sulfonated syndiotactic polystyrene: sorption of ionic liquid in the amorphous phase and of organic guests in the crystalline phase

Fourier Transform Infrared spectroscopy (FTIR) and Wide-Angle X-Ray Diffraction (WAXD) measurements have clearly established the occurrence of a dual sorption ability of sulfonated syndiotactic polystyrene samples, which exhibit the nanoporous d crystalline phase. In fact, large uptake (up to 20–30 wt%) of ionic liquid (IL; e.g. 1-ethyl- 3-methylimidazolium dicyanamide) occurs only in the hydrophilic amorphous sulfonated phases and does not disturb the hydrophobic nanoporous crystalline d phase. On the other hand, a large uptake of organic guests (e.g. naphthalene) occurs prevailingly in the nanoporous hydrophobic crystalline phase, independently of the presence of the IL in the amorphous phase, eventually leading to the formation of syndiotactic polystyrene co-crystalline phases. The thermal stability of IL can be largely increased by their inclusion in the amorphous phase of sulfonated syndiotactic polystyrene films.