Thermoreversible gelation of syndiotactic polystyrene in toluene and chloroform

Temperature-concentration phase diagrams have been established for syndiotactic polystyrene (sPS)/toluene gels and sPS/chloroform gels. The occurrence of polymer-solvent compound formation is shown in both systems and confirmed by neutron diffraction investigations. In particular it is found that a compound with a stoichiometry close to 1/1 occurs in both types of gels. Infra-red analysis show that the polymer chains take on a 2(1) helical form in both series of gels. In sPS/toluene gels, neutron scattering experiments reveal that the chains possess a worm-like conformation in the molten state while still retaining a conformation close to the 2(1) helix. The results are discussed in the light of a polymer-solvent intercalation model already proposed for sPS/benzene gels. (C) 1997 Elsevier Science Ltd.