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Proton‐NMR studies of polyacetal copolymers
Author(s) -
Ogawa Toshio,
Ishitobi Wataru,
Jinta Kazuya
Publication year - 1989
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1989.070380109
Subject(s) - copolymer , ethylene oxide , methylene , alkoxy group , tetramethylsilane , triad (sociology) , ethylene , polymer chemistry , oxide , polymer , gel permeation chromatography , materials science , end group , chemistry , organic chemistry , alkyl , catalysis , psychology , psychoanalysis
Sequence length of ethylene oxide and the amount of end groups in polyacetal copolymers were determined using proton NMR. Peaks from ethylene oxide usually appear in the region from 3.5 to 3.8 ppm, when tetramethylsilane was used as the internal standard. These peaks were divided into three triad sequences, i.e., MEM, MEE, EEE (E = ethylene oxide, M = methylene oxide) by referring to several polymers of similar structure. The sequence length in a copolymer prepared from ethylene oxide was 1.37 and that from trioxocan was 2.00. Small peaks from end groups usually appear in the region higher than 3.5 ppm. The peaks from methoxy and ethoxy groups were easily detected and determined quantitatively. The peak from hydroxy groups was detected after acetylation of a copolymer, because the original sample did not give a distinct peak corresponding to that group. The number‐average molecular weight of the copolymer prepared from trioxocane was estimated from the content of methoxy, ethoxy, and hydroxy groups. The value thus obtained was consistent with that obtained by gel permeation chromatography.