乙烯-乙烯醇共聚物氢键相互作用与链结构关系的变温溶液氢谱研究

用变温溶液核磁共振氢谱研究了不同组成的乙烯-乙烯醇共聚物在二甲亚砜溶液中的氢键相互作用.结果表明,乙烯醇单元中羟基的信号随温度升高而线性地向高场位移,且不同的三单元组中羟基信号的位移速率不同,表明羟基形成的氢键强度与链结构间存在相关性.

Hydrogen-bonding Interaction of Ethylene-Vinyl Alcohol Copolymers and Its Relation to the Chain Structures as Studied by VT 1H NMR Spectroscopy

The hydrogen bonding interaction of ethylene vinyl alcohol copolymer in DMSO solution was studied by variable temperature 1H NMR spectroscopy. It was found that the signals of the hydroxy protons of vinyl alcohol units shift to the upfield linearly with the increase of temperature, indicating the formation of the hydrogen bonds between the hydroxy groups and the solvent. The shift rates of these signals were found to be dependent on the chain structure and to decrease in the order of EVE>mEVV>rEVV>mmVVV>mrVVV>rrVVV triads, where m and r denote meso and racemic. Such a result indicates that the strength of hydrogen bonds formed by the hydroxy groups is dependent on the comonomer sequence and the stereo chemical structure of the copolymer. Contrary to the behavior of the hydroxy groups, the methine signals of the V unit were found to shift to the downfield linearly with the increase of temperature, demonstrating that the formation of hydrogen bonds also affects the chemical shift of protons on the neighboring group.