✦ LIBER ✦

29Si-NMR studies of dimethyl and vinylmethyl containing oligodiorganyl cyclosiloxanes and linear copolymers

✍ Scribed by M. Ramarao; S. Packirisamy; P. V. Ravindran

Book ID: 105337563
Publisher: John Wiley and Sons
Year: 1990
Tongue: English
Weight: 590 KB
Volume: 28
Category: Article
ISSN: 0887-624X
DOI: 10.1002/pola.1990.080280811

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✦ Synopsis

Abstract

^29^Si‐NMR has been used to identify and analyze oligomeric mixtures of diorganyl cyclosiloxanes of the general formula F~n~D~m−n~ (D = (CH~3~)~2~SiO, F = CH~3~(CH~2~CH)SiO, m = 3–5 and n = 0 −m). Chemical shift assignments were confirmed by comparing ^29^Si‐NMR and GC‐MS results for composition of the mixtures. The effect of vinyl group on the chemical shift of neighboring silicon atoms was estimated in terms of additivity parameters and good agreement was obtained between experimental and calculated chemical shift values. The distribution of dimethyl and vinylmethyl siloxy units in cyclosiloxanes is discussed. Pentad structures were observed in ^29^Si‐NMR spectra of poly(dimethyl‐co‐vinylmethyl)siloxanes and their intensities were found to be in confirmity with Bernoullian statistics.

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