Yuji Higaki,* Takumi Masuda, Shohei Shiomoto, Yukiko Tanaka, Hisao Kiuchi, Yoshihisa Harada, Masaru Tanaka
"Pronounced Cold Crystallization and Hydrogen Bonding Distortion of Water Confined in Microphases of Double Zwitterionic Block Copolymer Aqueous Solutions"
Langmuir, in press DOI: 10.1021/acs.langmuir.4c02254
Is the water in phase-separated hydrophilic polymer aqueous solutions, i.e. the water at the water-water interface, in the same state as bulk water?
Advanced materials leveraging water control are garnering considerable interest, with the state of water emerging as a critical aspect in material design. This study explored the impact of microphase separation on water using aqueous solutions of double zwitterionic diblock copolymers, specifically poly(carboxybetaine methacrylate) and poly(sulfobetaine methacrylate) (PCB2-b-PSB4). These copolymers form a mesoscale periodic ordered lattice structure, consisting of two distinct aqueous phases. Through differential scanning calorimetry and X-ray emission spectroscopy, it was found that water in these PCB2-b-PSB4 aqueous solutions exhibits pronounced cold crystallization and subtle distortions in hydrogen-bonding configurations. The dynamics, translational entropy loss of water, and Donnan potential due to the phase separation interface are likely to promote the cold crystallization. The modulation in the water state by mesoscale phase separation may be applicable to the development of molecular technologies that improve the performance of hydrogels and separation membranes, as well as to molecular systems that mimic cellular functions.
Takumi Masuda was in charge of this project. This paper is his fifth publication, and he is the author of two papers as second author and three as third author. How excellent he is! He carefully prepared samples and conducted DSC and XES experiments, while he had numerous discussions with me. It was a tough road to find consistent and reasonable scenario for the experimental results. I salute his sincere efforts on science. I wish his bright future and good health.
This is the collaboration work with Prof. Masaru Tanaka in Kyushu University and Prof. Yoshihisa Harada in The University of Tokyo with support from the JSPS KAKENHI budgets and Cooperative Research Program of the Network Joint Research Center for Materials and Devices (MEXT). It has been a great honor to have collaboration research with them on this project. Dr. Shohei Shiomoto, Dr. Hisao Kiuchi, and Yukiko Tanaka assisted with experiments and data analysis. I sincerely appreciate their support and advice on this research. Also, we appreciate Kumiko Araki for her kindness and warmful support on paperwork, Dr. Naoya Kurahashi and the beamline staff of Spring-8 BL07LSU for their extensive experimental support.
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