Small-angle neutron scattering study on the miscibility and concentration fluctuation of hydrogen-bonded polymer blends

Authors

  • Osamu Urakawa,

    Corresponding author
    1. Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 563-0043, Japan
    • Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 563-0043, Japan
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  • Hiroyoshi Ikuta,

    1. Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 563-0043, Japan
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  • Shogo Nobukawa,

    1. Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 563-0043, Japan
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  • Toshiyuki Shikata

    1. Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 563-0043, Japan
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Abstract

Thermal concentration fluctuation in the blends of deuterated poly(ethylene oxide) (dPEO) and poly(vinyl acetate-co-vinyl alcohol) [P(VAc-VOH)] with various VOH contents fOH were examined by small angle neutron scattering techniques at a fixed blend composition, dPEO/P(VAc-VOH) = 20/80 which is close to the critical composition. Blends at the highest fOH (=0.35) showed a non-Lorentzian scattering profile: specifically the scattering intensities at the low q (angle) region were suppressed compared to those expected from the random phase approximation (RPA) theory. However, for the blends at lower fOH (≤0.28), the profiles could be represented by the RPA. Using the RPA we determined effective values of the Flory-Huggins interaction parameter χeff as a function of fOH (=0–0.28). The χeff showed the minimum around fOH = 0.1–0.18 meaning the highest miscibility of the blend at these fOH. On the basis of the random copolymer theory, we evaluated the three interaction parameters χAc–EO, χEO–OH, and χAc–OH separately from the χeff(fOH) and found the order of magnitude; χAc–EO < 0 < χEO–OH < χAc–OH. The largest positive χAc–OH showing intrachain interaction in the P(VAc-VOH) copolymer was concluded to be the origin of the enhanced miscibility at around fOH = 0.1–0.18. On the basis of the Coleman and Painter's theory, the effects of hydrogen bonding on these three χA-B were discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2556–2565, 2008

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