FIBERS AND OTHER AGGREGATES OF OMEGA-SUBSTITUTED SURFACTANTS

Citation
Da. Jaeger et al., FIBERS AND OTHER AGGREGATES OF OMEGA-SUBSTITUTED SURFACTANTS, Langmuir, 13(21), 1997, pp. 5563-5569
Citations number
40
Categorie Soggetti
Chemistry Physical
Journal title
ISSN journal
07437463
Volume
13
Issue
21
Year of publication
1997
Pages
5563 - 5569
Database
ISI
SICI code
0743-7463(1997)13:21<5563:FAOAOO>2.0.ZU;2-B
Abstract
The aggregation in dilute aqueous solutions of several omega-substitut ed single-chain quaternary ammonium surfactants has been studied by Kr afft temperature and critical aggregation/micelle concentration measur ements and by cryo-transmission electron microscopy: (16-carboxyhexade cyl)trimethylammonium bromide (1a); (16-methoxycarbonylhexadecyl)trime thylammonium bromide (1b); (17,18-dihydroxyoctadecyl)trimethylammonium bromide (1c). Octadecyltrimethylammonium bromide (2) was included for comparison. The aggregation of 1a was also studied by Raman spectrosc opy. Surfactant 1a at pH 6.8 forms ribbonlike fibers with lengths of u p to 1.2 mu m and cross sections of 3-4 nm x 12-16 nm; at pH 2.2, ribb on to rodlike fibers; and at pH 11.5, wormlike aggregates. Surfactants 1b and 1c at pH 6.8 form I-ed-shaped aggregates. The Raman spectrosco py results indicated that 1a is not in a fully extended conformation w ithin its fibers at pH 6.8. Tentative structural models have been prop osed for the aggregates of surfactants 1.