Physical Gelation of Syndiotactic Polystyrene in the Presence of Poly(ethylene oxide)

Syndiotactic polystyrene (s-PS) in dichloroethane (DCE) was gelated thermoreversibly in the presence of poly(ethylene oxide) (PEO). The effect of the dosage and molecular weight of coexistent PEO on the gelation has been investigated. The gelation temperature increased with increasing the composition ratio of PEO to DCE and the molecular weight of PEO. Wide angle X ray diffraction measurements revealed that an increase of the composition ratio of PEO to DCE in the gel led to change the crystal structure of s-PS from a helical conformation to a trans-zigzag one.When DCE was removed from the gel completely by drying under vacuum at 70°C for 24 hours, a novel polymer blend consisting of s-PS and PEO was obtained. Dynamic modulus analysis measurements revealed that it had a unique long rubbery plateau from a grass transition temperature (Tg) or a melting temperature (Tm) of PEO’s depending with their molecular weights to Tm of s-PS. It indicates that the crystallite of s-PS not only plays a role of the network junction in the polymer blend but also prevents the macroscopic phase separation between s-PS and PEO.