Temperature Induced Structural Changes in Syndiotactic Polystyrene/cis-Decalin Systems

Abstract

Phase transformations in solutions of syndiotactic polystyrene in cis-decalin has been investigated by differential scanning calorimetry, wide and small angle X-ray scattering, and Fourier transformed infrared spectroscopy. The in-situ performed experiments enabled identification of the different modifications without solvent removal. Quenching a solution leads to formation of the helical δ-phase. On heating, this phase transforms into the planar zigzag -phase. The transformation of the helical phase (δ) into the planar zigzag ( ) during heating proceeds via a melting-recrystallization process.

Structure evolution and kinetics steps of the melting process of thermoreversible polymer gels

“…Roels et al have investigated the phase transformation of the sPS/cis-decalin gels by X-ray scattering and Fourier transformed infrared spectroscopy, and found that the gels transform directly into the b form around 140 C without passing through the g form. 20 Rastogi and coworkers have investigated the melting process by X-ray scattering and Raman spectroscopy and it was reported that when heating sPS/benzyl methacrylate gels, the helical d form transformed to g phase firstly then a transition from the helical phase into the planar-zigzag phase (b phase) happened. 21 Thus, in this study, the infrared absorption and XRD spectra of sPS/chloroform gel at various temperatures were performed during the heating process for the identification of the conformational transition.…”

“…Some research focused on the melting process of sPS/solvent systems. Roels 20 and Rastogi 21 studied the phase transformation of the sPS/cis-decalin system and sPS/benzyl methacrylate gel, respectively, and they found that the gel either transform directly into the b form or transform into the b form through the g form. However, Daniel's previous study on the definition of thermoreversible gels demonstrated that the sPS/ trans-decalin system was not regarded as a gel because the system exhibited a spherulitic morphology and the criteria proposed by Guenet was not fulfilled.…”

“…To the authors' knowledge, several techniques are available for studying gelation or melting process of sPS, like infrared spectroscopy (IR), small and wide angle X-ray scattering (SAXS), small-angel neutron scattering (SANS), differential scanning calorimetry (DSC) and scanning electronic microscope (SEM) etc. 20,21,25,26 It is worth noting that these methods have advantages and shortcomings when gel melting process is concerned. For example, SAXS and SANS are not easy to access.…”

An In Situ SAXS/WAXS/Raman Spectroscopy Study on the Phase Behavior of Syndiotactic Polystyrene (sPS)/Solvent Systems: Compound Formation and Solvent (Dis)ordering

“…Further, preliminary in situ X-ray scattering experiments were performed on these systems for a few concentrations. 19 To have a detailed insight into the structural changes during the phase transitions, simultaneous small-and wide-angle X-ray scattering (SAXS and WAXS) and Raman spectroscopy experiments were performed. While SAXS and WAXS can give insight into the morphological changes occurring in the long-and small-range order, the conformational changes occurring during the phase transformations can be followed by Raman spectroscopy.…”

Study on the Crystalline Structure Transition of Syndiotactic Polystyrene Film during Heat Treatment by Two-Dimensional Infrared Correlation Spectroscopy

“…It has been demonstrated that syndiotactic polystyrene shows a very complex polymorphism [8][9][10][11][12][13][14][15][16][17][18] as crystallization conditions are varied. a and b, which are characterized by stable planar zigzag conformations, are found in the melt or glassy state of sPS under different thermal-crystallization conditions.…”