Abstract: In this work, the chain structure of the liquid hydroxy terminated TEOwas described by 1D¹³C NMR and 2D COSYspectroscopies.Some difficulties in recognition of the ¹³C spectra of TEOcome from the overlap of peaks or small difference for chemical shifts.The assignment of the peaks in ¹³C spectra of TEOwas discussed deeply with information provided from 2D H-H COSYand C-H COSYexperiments.The diads and triads distribut ion were determined by the gated decoupling ¹³C NMR spectrum and based on the change of sequence structure with the content ratio of EO/THF.The four peaks in the high field of ¹³C NMR spectrum of TEO(50%EO) sample solution in CDCl₃, obviously, were assigned to TTT, TTE, and ETE(-CH₂-).In the lower field, the six peaks were identified as ETE(71.12 ppm), TTE(71.08 ppm), TEE 3nd EEE(70.85 ppm), EEE(70.55 ppm), EET(70.55 ppm), TTT(70.52 ppm),TTE (70.52 ppm), TET(70.02 ppm), EET(70.02 ppm).The experiment results indicate that the average functionalities(f_n) are about 2, and the average alternated degree close to 50 per cent,so, TEO's are copolyether of the random and the alternation.

Key words: NMR spectroscopy, Sequence distribution, Random copolyether, Chain structure