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Changes in the structure and viscosity of interpolymer complexes formed by poly(ethyl oxazoline) and poly(methacrylic acid) by controlling interpolymer hydrogen bonds

Polymer Journal volume 58, pages 159–165 (2026)Cite this article

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Abstract

The structure of interpolymer complex formed by poly(2-ethyl-2-oxazoline) and poly(methacrylic acid) was changed by controlling the hydrogen bonds between the polymer chains by changing the solvent pH or adding urea. The viscosity of solution containing the interpolymer complex drastically increased in solvent at pH~12, then decreased at pH~13. The infrared spectra of the interpolymer complexes formed in solvents at different pH indicated that the formation of hydrogen bonds among the polymer chains decreased with an increase of pH. These results were explained by a model in which the dimension of the interpolymer complex increased at pH~12, and the interpolymer complex dissociated into free polymer chains at pH~13. The hydrogen bonds of the interpolymer complex were also suppressed by adding urea to solvents. The viscosity of the solution containing the polymer-complex increased drastically when the urea concentration was over 6 M. The increase induced by the addition of urea can also be explained by the increase in the dimension of the interpolymer complex.

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Acknowledgements

This work was partially performed under Cooperative Research Program of “Network Joint Research Center for Materials and Devices”

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  1. Department of Applied Chemistry, Kogakuin University, Hachioji, Japan

    Yasuhiro Matsuda

  2. Department of Applied Chemistry and Biochemical Engineering, Shizuoka University, Hamamatsu, Japan

    Hiroto Emi

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  1. Yasuhiro Matsuda
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  2. Hiroto Emi
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Correspondence to Yasuhiro Matsuda.

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Matsuda, Y., Emi, H. Changes in the structure and viscosity of interpolymer complexes formed by poly(ethyl oxazoline) and poly(methacrylic acid) by controlling interpolymer hydrogen bonds. Polym J 58, 159–165 (2026). https://doi.org/10.1038/s41428-025-01112-x

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