Abstract
The crystal structure transition of syndiotactic polystyrene film from the helical conformation to the more stable planar zigzag conformation during a heating process was studied using Fourier transform infrared (FT-IR) spectroscopy in combination with two-dimensional (2D) correlation analysis and perturbation-correlation moving-window 2D analysis. The sequence of different conformations during the transition was investigated by analyzing two-dimensional FT-IR correlation spectra in the spectral ranges of 800–700 cm<sup>−1</sup> and 600–500 cm<sup>−1</sup>. It was observed that the conformation of δ helical changes prior to γ helical, and the γ helical phase is faster than the α planar zigzag phase. By utilizing the 2D asynchronous correlation spectra, the 744 cm<sup>−1</sup> band, which is usually incorporated in the broad 750 cm<sup>−1</sup> band, can now be uniquely attributed as the α zigzag configuration for the first time. Furthermore, by employing thermal perturbation, the shorter helical segments consisting of <i>m</i> = 7–12 and <i>m</i> = 12–20 monomeric units were disturbed in a shorter time than the longer helical segments <i>m</i> = 20–30 during the heating process.
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