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

Decisive properties of solvent able to form gels with syndiotactic polystyrene

“…After cooling, the appearances of the SPS/solvent systems were divided into three categories: (1) gel, (2) paste, and (3) sherbet states. These results perfectly corresponded to the case where SPS was dissolved in NB [21] and fragrant molecules [22]. The solutions categorized to be a gel state were transparent and elastic, and did not change their shapes by tilting them for months.…”

“…However, it was wrong. For example, we reported in our previous paper [21] that 10 wt/wt% of SPS in 4B did not form a gel but produced non-lamellar spherulitic structure consisting of g crystalline phase, but in the present work, 1.1 wt/wt % of SPS in 4B was found to form a gel, which was ascertained by SEM observation, WAXD patterns, and FT-IR measurements. It follows from this result that the gelation of SPS strongly requires the situation where an SPS chain is surrounded by solvent molecules.…”

“…Needless to say, the majority of these gel characterization was carried out for dried gels after perfectly or partially removal of solvent. However, we have already shown that the pristine SPS/NB solutions assigned to a gel state consist of polymer-solvent molecular compounds by means of DSC, and their dried gels exhibited the spectroscopic evidence (i) to (iii) shown above [21]. Fig.…”

“…Our previous works [21,22] suggested that these states were produced by recrystallization of SPS crystalline Although there are not many examples of solvents that produce SPS in the g crystalline phase, the main diffraction peaks of SPS/5B [21] and SPS/(À)-b-pinene (F3) [22] were comparable with the reference values of SPS g crystalline phase; the WAXD peaks at 2q of SPS/5B and SPS/(À)-b-pinene (F3) were 9. 33 [33].…”

“…We employed serial n-alkylbenzenes (NB: C 6 H 5 eC N H 2Nþ1 (N ¼ 1e10)) [21] and several typical fragrant molecules [22] as solvents of SPS in order to clarify what conditions of solvent can produce SPS gel when SPS concentration is 10 wt/wt%. After dissolving SPS at high temperatures, we checked what morphologies they showed after cooling.…”