Viscosity of fractions from end-linked polystyrene star macromolecules

✍ Scribed by M. Weissmüller; W. Burchard

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 778 KB
• Volume: 48
• Category: Article
• ISSN: 0323-7648
• DOI: 10.1002/actp.1997.010481207

✦ Synopsis

A number of OH-terminated three-arm star molecules were prepared by anionic polymerization with a specially functionalized initiator. The stars were crosslinked over the OH groups with varying amounts of toluene-2,4-diisocyanate. The samples were fractionated by size exclusion chromatography (SEC) on-line with a low angle laser light scattering (LALLS) and a viscosity (VISC) detector. The Kuhn-Mark-Houwink-Sakurada (KMHS) relationships from the various samples resulted in a common relationship. Shrinking parameters gj [qlj b/[q]j,,in were determined for each slice and could satisfactorily be interpreted on the basis of the Zimm-Stockmayer theory in connection with a suggestion by Kurata et al. The Kurata suggestion was checked with data from star molecules. The examination revealed that randomly branched and star-branched macromolecules exhibit significantly different hydrodynamic behavior. The ratio of the Fox-Flory coefficients @&Dlin in the relationship [q] = @(I?;/!) increases in both cases with branching. This is a consequence of the enhanced segment density and the resulting increase in the hydrodynamic interaction.