Polymorphic structures and molecular vibrations of syndiotactic polystyrene

Crystallization Condition of Glassy Syndiotactic Polystyrene in Supercritical CO2

“…Several infrared bands characteristic of the t 2 g 2 helical conformation were reported by Kobayashi et al 9 In order to monitor the crystallization process of this modification, we chose the 572 cm −1 band, because this band is very sharp and is comparatively isolated from the other bands. This band is assigned to the out-ofplane mode of C-H bending of the phenyl group, and is very sensitive to the conformation.…”

“…This temperature is much lower than the crystallization temperature of the glassy sPS reported previously (about 140 • C). 9 According to the result by Handa et al, the crystallization temperature decreased with increasing pressure of CO 2 . [18][19][20] This effect is explained by plasticization due to CO 2 dissolved in the film.…”

“…Kobayashi and his coworkers revealed the characteristic vibrational modes for these conformations using the infrared and Raman spectroscopies. [9][10][11][12][13] It is worth noting that the formation of the modifications with the t 2 g 2 sequence requires the assistance of an organic solvent. Several methods are known to obtain the t 2 g 2 crystal forms, i.e., casting from an organic solution, soaking the glassy sPS in an organic non-solvent, and exposing the glassy sPS in vapor of an organic solvent.…”

“…For example, chloroform, benzene, toluene, and other many aromatic compounds were found to induce the δ-form. 5,9 Since the δ-form is one of the host-guest type crystals formed by the sPS chains and solvent molecules, the cavity created by the sPS chains in the crystal is believed to play an important role to form the complex structure. 8,14 The γ-form also takes the t 2 g 2 conformation but is formed without solvents.…”

Absorption Kinetics of Phenol into Different Size Nanopores Present in Syndiotactic Polystyrene and Poly (p-methylstyrene)

“…It has been reported that there are five crystalline modifications. The [4][5][6][7][8] and [9,10] forms consist of a planar zigzag chain with period of 5.1 Å, whereas the [11][12][13], [14][15][16][17], and [18][19][20] forms adopt a helical structure with a trans-trans-gauche-gauche (ttgg) conformation, having a period of 7.7 Å. The crystal with an all-trans conformation is a thermally stabilized form induced above about 180 °C and its high melting temperature around 270 °C is expected to be useful as an engineering plastic.…”