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Synthesis and characterization of macrocyclic poly(.-methylstyrene)

Synthesis and characterization of macrocyclic poly(.-methylstyrene) AbstractThe synthesis is described of macrocyclic poly(α-methylstyrene) (PAMS) by the lithium naphthalide initiated polymerization of AMS followed by high dilution end to end coupling with 1,4-bis(bromomethyl)benzene (DBX). The cyclization is carried out by simultaneous addition of tetrahydrofuran solutions of the PAMS dianion and DBX at about -100ºC. A sample of the matching linear PAMS is obtained by protonation of the PAMS dianion. The purified cycles are obtained by fractional precipitation that is monitored by size exclusion chromatograhy. A careful study of the coupling reactions carried out at high concentrations indicates that coupling is efficient and this is borne out by the ratios (<G>) of apparent molecular weights (MW’s) of cycles and matching linear polymers. The <G> values of the cycles tend to vary with MW in the same manner as was demonstrated for polystyrene and other vinyl polymers and increase from around 0.74 at MW of about 30000 to values of around 0.82 at MW of about 2500. A higher apparent <G> value was observed for a very low MW PAMS but this sample could not be purified and analyzed adequately. As was also observed for other macrocyclic vinylpolymers, the glass transition temperatures of the cycles are MW independent above MW of about 5000 but decrease sharply at lower MW’s. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png e-Polymers de Gruyter

Synthesis and characterization of macrocyclic poly(.-methylstyrene)

e-Polymers , Volume 1 (1): 1 – Dec 1, 2001

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Publisher
de Gruyter
Copyright
© 2013 by Walter de Gruyter GmbH & Co.
ISSN
2197-4586
eISSN
1618-7229
DOI
10.1515/epoly.2001.1.1.54
Publisher site
See Article on Publisher Site

Abstract

AbstractThe synthesis is described of macrocyclic poly(α-methylstyrene) (PAMS) by the lithium naphthalide initiated polymerization of AMS followed by high dilution end to end coupling with 1,4-bis(bromomethyl)benzene (DBX). The cyclization is carried out by simultaneous addition of tetrahydrofuran solutions of the PAMS dianion and DBX at about -100ºC. A sample of the matching linear PAMS is obtained by protonation of the PAMS dianion. The purified cycles are obtained by fractional precipitation that is monitored by size exclusion chromatograhy. A careful study of the coupling reactions carried out at high concentrations indicates that coupling is efficient and this is borne out by the ratios (<G>) of apparent molecular weights (MW’s) of cycles and matching linear polymers. The <G> values of the cycles tend to vary with MW in the same manner as was demonstrated for polystyrene and other vinyl polymers and increase from around 0.74 at MW of about 30000 to values of around 0.82 at MW of about 2500. A higher apparent <G> value was observed for a very low MW PAMS but this sample could not be purified and analyzed adequately. As was also observed for other macrocyclic vinylpolymers, the glass transition temperatures of the cycles are MW independent above MW of about 5000 but decrease sharply at lower MW’s.

Journal

e-Polymersde Gruyter

Published: Dec 1, 2001

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