A trial to clarify a cause of forming physical gels: Morphology of syndiotactic polystyrene in n-alkylbenzene

We dissolved low concentration of syndiotactic polystyrene (SPS) in serial n-alkylbenzenes (NB: C6H5–CNH2N+1 (N = 1–10)) at high temperatures and observed the morphology and structure after cooling by SEM, IR, DSC, and WAXD. The morphology of SPS in NB changes with N: (I) N = 1–3, SPS/NB forms a gel with fibril structure networking three-dimensionally, (II) N = 4–6, SPS/NB produces paste-like state where SPS chains with 21-helix conformation gather together to form SPS γ crystalline phase, and (III) N = 7–10, SPS/NB produces sherbet-like state where SPS chains with trans zigzag conformation gather together to form SPS β crystalline phase. We have discussed a cause of forming physical gels of SPS together with the reason why the morphology of SPS/NB depends on N.