Raman Vibrational Studies of Syndiotactic Polystyrene. 1. Assignments in a Conformational/Crystallinity Sensitive Spectral Region

Abstract

A detailed analysis of the Raman spectrum of syndiotactic polystyrene, sPS, in the region 600−850 cm-1 has been undertaken. As sPS exhibits considerable polymorphism, spectra of various preparations including melt-crystallized sPS (α/β form), solvent-crystallized sPS (γ/δ forms), and quenched glassy material were studied. The ν1 vibration of the phenyl ring (ring breathing mode) has been shown to manifest itself through the presence of two peaks resulting from local conformational changes in the alkyl backbone. The peak centred around 773 cm-1 has been assigned to an all-trans backbone sequence whereas the higher frequency feature at ∼798 cm-1 is attributed to mixed trans/gauche conformations. For comparison the spectrum of atactic polystyrene was also studied, and the presence of a weak shoulder is assigned to a syndiotactic all-trans component within the polymer. Further study of a cross section of molded material exhibiting a skin/core structure reveals the continuous way in which the relative size, position, width, and intensity of these features vary with changing crystallinity.

Surface‐enhanced Raman scattering from polystyrene on gold clusters

“…Band assignments, with symmetry information, are given in column 5. References [28][29][30][31][32][33] give ordinary Raman data only. References [15,26] give both ordinary Raman and SERS data.…”

Process analysis of phase transformation of α to β-form crystal of syndiotactic polystyrene investigated in supercritical CO2

“…sPS exhibits a multiple melting peaks in the DSC thermograms because of different crystal structures and/or re-crystallization during the DSC scan. A rapid heating rate, 80 8C/min, was found to minimize the recrystallization [45]. Therefore, all the samples were scanned at 80 8C/min in a dry nitrogen atmosphere in this study in order to avoid the influence of re-crystallization during the DSC measurement on the melting behaviors of sPS.…”

Thermal‐Induced Crystal/Conformation Transformations in Syndiotactic Polystyrene Films Treated with Different Solvents

“…Similar results have also been described in several previous papers. [3,4] Like sPS/1,1,2,2-tetrachloroethane or other sPS crystal/solvent complexes, [4,[13][14][15][16][17][18] the g ! a 0 transition always occurs at about 200 8C resulting in an obvious exothermic peak that is associated with recrystallization of the melted g-type crystal during the course of DSC scanning upon further heating.…”

“…Recently, subjects of polymorphism of sPS have been widely investigated by using differential scanning calorimetry (DSC), [1,2] X-ray diffraction, [3][4][5] transmission electron microscopy, electron diffraction, [6][7][8] Raman scattering and Fourier-transform infrared spectroscopy (FTIR), [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] etc. There are four known crystals (a-, b-, d-, and g-crystals) in sPS.…”

“…Thus, the crystal phases and chain conformations in the polymersolvent complexes or polymer crystals can be effectively analyzed using FTIR spectroscopy. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] Fourier-transform infrared spectroscopy (FTIR) technique has been commonly and widely used to investigate crystal polymorphism and chain conformations in semicrystalline polymers, [18][19][20][21][22][23] and numerous applications have been demonstrated on investigating the vibrational spectra changes with polymorphism alteration in sPS during various solvent/thermal treatments. By using X-ray diffraction characterization, the preliminary evidences show the different phase transition mechanisms for various polymer-solvent complexes depending on the type of the solvent included in the crystal of the d-type.…”