Investigations on poly(ethylene oxide)–p-bromotoluene intercalate by in situ heating Fourier transform IR spectroscopy |
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Authors: | Y. Fang X. Zhu D. Yan Q. Lu P. Zhu |
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Affiliation: | (1) College of Chemistry and Chemical Technology, Shanghai Jiao Tong University, Shanghai 200240, China e-mail: dyyan@mail.sjtu.edu.cn Fax: + 86-21-54741297, CN;(2) Instrumental Analysis Center Shanghai Jiao Tong University 1954 Huashan Road Shanghai 200030, China, CN |
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Abstract: | By means of differential scanning calorimetry, the phase diagram of the poly(ethylene oxide)–p-bromotoluene system (PEO–PBT) is established. It is found that PEO and PBT form a molecular intercalate with a molar stoichiometry of 22%, which corresponds to two PBT molecules for seven ethylene oxide units. The intercalate undergoes an incongruent melting at 48.5 °C on heating. Wide-angle X-ray diffraction experiments indicate that the PEO–PBT intercalate has a crystalline structure different from pure PEO. From variable-temperature Fourier transform IR spectroscopy investigations, it is believed that the macromolecular chains in the PEO–PBT intercalate adopt a 7/2 helical conformation which is identical to that in the pure PEO. There are a considerably large number of helical structures in the melt of the PEO–PBT intercalate at temperatures ranging from 50 to 60 °C even though the crystalline lattices collapsed in the aforementioned temperature range. Such a kind of melt is in a conformationally high order state. Received: 5 March 2001 Accepted: 31 August 2001 |
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Keywords: | Poly(ethylene oxide) Molecular intercalate Phase diagram Incongruent melting Helical conformation |
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