Structural Phase Transitions of Syndiotactic Polystyrene upon the Guest Extraction Process

Abstract

In this work, the effects of initial morphology/crystalline form and the guest molecules used for the preparation of syndiotactic polystyrene (sPS) cocrystals, on the structural phase transitions of sPS upon the guest extraction process were systematically investigated. For that purpose, samples having two different initial morphologies such as amorphous and g form were used as the starting materials and guests such as chloroform and toluene were used for the preparation of sPS co-crystals. Selective extraction of guest molecules resulted in complex phase transitions in the host structure. In the case of toluene-treated amorphous samples, the structure transformed into the d (de) form. On the other hand, the chloroformtreated amorphous samples transformed into the mixture of nanoporous d (de) and e (ee) forms. When chloroform-treated g form samples were used for the guest extraction, the e (ee) form with channel-shaped cavities was obtained. In contrast, when toluene-treated g form samples were for used guest extraction, the co-crystal structure transformed to its initial crystalline form, i.e., g form, instead of forming nanoporous structure.