Abstract: The hydrogen bonding interaction of ethylene vinyl alcohol copolymer in DMSO solution was studied by variable temperature ¹HNMR 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.

Key words: Ethylene vinyl alcohol copolymer, Hydrogen bonds interaction, Chain structure, Variable temperature high resolution ¹HNMR