Chinese Journal of Chemical Physics, Volume. 33, Issue 5, 540(2020)
Ultrafast Infrared Spectroscopic Study of Microscopic Structural Dynamics in pH Stimulus-Responsive Hydrogels†
Hydrogels show versatile properties and are of great interest in the fields of bioelectronics and tissue engineering. Understanding the dynamics of the water molecules trapped in the three-dimensional polymeric networks of the hydrogels is crucial to elucidate their mechanical and swelling properties at the molecular level. In this report, the poly(DMAEMA-co-AA) hydrogels were synthesized and characterized by the macroscopic swelling measurements under different pH conditions. Furthermore, the microscopic structural dynamics of pH stimulus-responsive hydrogels were studied using FTIR and ultrafast IR spectroscopies from the viewpoint of the SCN- anionic solute as the local vibrational reporter. Ultrafast IR spectroscopic measurements showed the time constants of the vibrational population decay of SCN- were increased from 14±1 ps to 20±1 ps when the pH of the hydrogels varied from 2.0 to 12.0. Rotational anisotropy measurements further revealed that the rotation of SCN- anionic probe was restricted by the three-dimensional network formed in the hydrogels and the rotation of SCN- anionic probe cannot decay to zero especially at the pH of 7.0. These results are expected to provide a molecular-level understanding of the microscopic structure of the cross-linked polymeric network in the pH stimulus-responsive hydrogels.
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Jian Hong, De-xia Zhou, Hong-xing Hao, Min Zhao, Hong-tao Bian. Ultrafast Infrared Spectroscopic Study of Microscopic Structural Dynamics in pH Stimulus-Responsive Hydrogels†[J]. Chinese Journal of Chemical Physics, 2020, 33(5): 540
Received: Jun. 13, 2020
Accepted: Jul. 13, 2020
Published Online: Apr. 21, 2021
The Author Email: Bian Hong-tao (htbian@snnu.edu.cn)