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Updated: Jul 13, 2026

Advances in Nanoscale Infrared Spectroscopy to Explore Multiphase Polymeric Systems
Published on: June 23, 2023
Structure analysis of poly(N-isopropylacrylamide) using near-infrared spectroscopy and generalized two-dimensional
Bingjie Sun1, Yinan Lin, Peiyi Wu
1The Key Laboratory of Molecular Engineering of Polymers (Ministry of Education), and Department of Macromolecular Science, Fudan University, Shanghai 200433, PR China.
Abstract:
Based on a detailed study of the fundamental vibrations in the mid-infrared (MIR) region and supported by NH-proton deuteration results, the assignment of the overtone and combination bands in the near-infrared (NIR) spectrum of poly(N-isopropylacrylamide) (PNIPAM) is presented. Variable-temperature experiments and two-dimensional correlation infrared spectroscopy are used to determine the chemical mechanism and changing sequence of groups in PNIPAM; we conclude that bonded NH groups turn into free NH groups during the heating process, while the CH groups on the side-chains change prior to those on the main chains. A heterospectral dynamical correlation between the NIR and MIR regions or H-included groups in both regions was also performed. The temperature-induced dissociation of the hydrogen-bonded NH groups is found to proceed earlier than the conformational changes in the hydrocarbon chains.
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