Proton-NMR studies of polyacetal copolymers

✍ Scribed by Toshio Ogawa; Wataru Ishitobi; Kazuya Jinta

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 338 KB
• Volume: 38
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1989.070380109

✦ Synopsis

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 trioxocane 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 group 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.