Sun Bingjie, Lin Yinan, Wu Peiyi
The Key Laboratory of Molecular Engineering of Polymers (Ministry of Education), and Department of Macromolecular Science, Fudan University, Shanghai 200433, PR China.
Appl Spectrosc. 2007 Jul;61(7):765-71. doi: 10.1366/000370207781393271.
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.
基于对中红外（MIR）区域基本振动的详细研究，并得到NH质子氘代结果的支持，本文给出了聚（N-异丙基丙烯酰胺）（PNIPAM）近红外（NIR）光谱中泛频带和组合带的归属。采用变温实验和二维相关红外光谱来确定PNIPAM中基团的化学机理和变化顺序；我们得出结论，在加热过程中，键合的NH基团转变为游离的NH基团，而侧链上的CH基团比主链上的CH基团先发生变化。还对NIR和MIR区域或两个区域中含H基团进行了异谱动力学关联。发现氢键合的NH基团的温度诱导解离比烃链的构象变化更早发生。
