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Salt concentration dependency of the hydrated swollen structure of cholinephosphate-type polyzwitterion brushes

Polymer Journal volume 57, pages 291–301 (2025)Cite this article

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Abstract

The swollen thicknesses of zwitterionic polymer brushes with phosphorylcholine (PC), cholinephosphate (CP), sulfobetaine, and carboxybetaine groups were measured in aqueous sodium chloride (NaCl) or calcium chloride (CaCl2) solutions via force curve measurements by scanning probe microscopy (SPM) and neutron reflectivity measurements. PC and CP have different charge positions in betaine units consisting of ammonium and phosphate. The PC-type polymer brush did not distinctly reduce the swollen thickness in either the NaCl or CaCl2 solution, even at 1000 mM. However, the swollen thickness of the CP-type polymer brushes was clearly reduced in the aqueous CaCl2 solution. Unlike the phosphate of PC, which is located inside the betaine unit, the phosphate of CP tends to form insoluble calcium phosphate, resulting in the collapse of the brush structure.

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Acknowledgements

This research was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant-in-Aid for Scientific Research A (21H04741) and C (23K04843). M.K. thanks Yuki Kodama and Kaito Inoue (Graduate School of Engineering, Kogakuin University) for their technical support. NR measurements were performed under the research proposals of 2019B0084, 2020B0433, and 2021B0327.

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Authors and Affiliations

  1. Graduate School of Engineering, Kogakuin University, 2665-1 Nakano-cho, Hachioji, Tokyo, 192-0015, Japan

    Takumi Komiya

  2. Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan

    Norifumi L. Yamada

  3. School of Advanced Engineering, Kogakuin University, 2665-1 Nakano-cho, Hachioji, Tokyo, 192-0015, Japan

    Motoyasu Kobayashi

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Komiya, T., Yamada, N.L. & Kobayashi, M. Salt concentration dependency of the hydrated swollen structure of cholinephosphate-type polyzwitterion brushes. Polym J 57, 291–301 (2025). https://doi.org/10.1038/s41428-024-00991-w

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