The Fiber Society 2017 Spring Conference : Next Generation Fibers for Smart Products, May 17-19, 2017, Aachen, Germany

The stereoregular syndiotactic rich polyacrylonitrile (PAN) was successfully prepared by solid state polymerization. In FT-IR spectra, no IR characteristic bands existed, however. Configurational difference appeared in the intensity of methylene (CH2) bands. The intensity was in the following order: in the stretching mode (ν), isotactic > atactic > syndiotactic, whereas in the deformational mode (δ), the results were visa versa, syndiotactic > atactic > isotactic. Dipole moment (DM) of each PAN was calculated by using 3 different stereochemical models (4 monomer sequences). The calculated data agreed completely with the above IR results (the order of the intensity relationships), which suggest the assumption employed is correct and valid. INTRODUCTION: Infrared (IR) spectroscopy is a powerful analytical tool for the investigation of molecular structure and physical properties of polymers. Dipole moment (DM) is related to IR absorption spectra, whereas polarizability (induced dipole) does to Raman scattering spectra. There is very little evidence indicating how the DM is related to the IR data. Quite recently, syndiotactic rich PAN’s were prepared by solid state polymerization by using Zeolites [1]. This is the first case, where syndiotactic rich PAN was synthesized actually, and its configuration was confirmed by C NMR spectra. In the IR spectra, there was no characteristic band in syndiotactic PAN. This makes a clear contrast with the results of isotactic PAN [2]. However, detailed analysis showed that configurational difference appeared in the intensity of CH2 bands. RESULTS AND DISCUSSION: In IR spectra of PAN, 3 peaks were clearly seen at 2940 and 1460cm, and 2240cm. The former two were CH2 bands, while the 3 was CN one. The difference appeared in the intensity of the CH2 band. DM of 3stereoregular sequence of PAN across cross sectional view was calculated by using tetrad-models (4 monomer units) (Figure 1). Total DM was separated into parallel (ν) and vertical components (δ). Figure 2 shows the results. Fig. 1. Calculation of the DM based on 3 PAN’s chain Fig. 2. The results of the calculated DM CONCLUSION: The intensity difference of methylene CH2 bands (ν,δ) in PAN was revealed by the detailed quantitative FT-IR analysis. DM of 3 stereoregular PAN’s chains was calculated by using tetrad-models. Agreement between the calculation and IR experimental results was quite good. It was verified that the order of the intensity of the CH2 bands in FT-IR spectra is determined by the DM of stereochemical structure of PAN. Polymer Optical Fibers Materials for POF Production: Scattering and Transmission in Fiber Optics