Daiki Ihara, Yuji Higaki,* Norifumi L. Yamada, Fumiya Nemoto, Yasuhiro Matsuda, Ken Kojio, Atsushi Takahara*
"Cononsolvency of Poly[2-(methacryloyloxy)ethyl phosphorylcholine] in Ethanol-Water Mixtures: A Neutron Reflectivity Study"
Langmuir, in press (2021) DOI: 10.1021/acs.langmuir.1c01762
This paper was published as an article in the Langmuir Special Issue: Françoise Winnik Memorial Issue. Prof. Françoise Winnik unexpectedly passed away last February. I will sincerely miss her human kindness, profound scientific expertise. It is my great honor to take part in the memorial issue with our research associating with her work. May her soul rest in peace.
“What is the molecular mechanism of cononsolvency of zwitterionic polymers?”
A zwitterionic polymer, PMPC, exhibits unique solubility in ethanol–water mixtures, a phenomenon referred to as cononsolvency, where a polymer chain is soluble in two pure solvents but insoluble in the solvent mixtures with specific mixing ratios. The molecular mechanism for the peculiar solubility has not understood and been under debate. Winnik and co-workers proposed a statistical mechanical model employing the concepts of competitive hydrogen bonding and cooperative hydration for analyzing the cononsolvency of PNIPAM in alcohol–water mixtures. We verified the theory by revealing the solvent composition in the collapsed but poorly solvated PMPC brushes in ethanol–water cononsolvents by means of neutron reflectivity experiments employing the contrast variation approach. The consistency indicated that the statistical mechanical model proposed by Winnik and co-workers is experimentally rationalized as the molecular mechanism for the cononsolvency of PMPC.
Daiki Ihara was in charge of this work. He is a very smart and rational guy with cool crew-cut hair style. Somehow, he loves “Hokkaido”. We just spent together four months, then I transferred to current position. So, he was urged to conduct his research by himself with my support through online meeting. Under the tough situation, he worked logically to produce the fantastic research output. This work is inherited to my current works. I believe that this work and his efforts certainly progress the soft matter science. I wish him all the best in his future work.
I appreciate all coauthors who participated in this project. I would like to express my sincere gratitude to Prof. Takahara for encouraging this exiting research project. Also, the experiments could be never done without the cooperation of Prof. Yamada who manage NR instrument and support out experiments.
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