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Titolo:
Interdigitation of an intercalated surfactant bilayer
Autore:
Venkataraman, NV; Vasudevan, S;
Indirizzi:
Indian Inst Sci, Dept Inorgan & Phys Chem, Bangalore 560012, Karnataka, India Indian Inst Sci Bangalore Karnataka India 560012 560012, Karnataka, India
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 32, volume: 105, anno: 2001,
pagine: 7639 - 7650
SICI:
1520-6106(20010816)105:32<7639:IOAISB>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
NORMAL-ALKYL CHAINS; H STRETCHING MODES; SOLID-STATE NMR; PHOSPHATIDYLCHOLINE BILAYERS; CONFORMATION; MOTION; PHASE; SPECTROSCOPY; MEMBRANES; MOLECULES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
36
Recensione:
Indirizzi per estratti:
Indirizzo: Vasudevan, S Indian Inst Sci, Dept Inorgan & Phys Chem, Bangalore 560012, Karnataka, India Indian Inst Sci Bangalore Karnataka India 560012 taka, India
Citazione:
N.V. Venkataraman e S. Vasudevan, "Interdigitation of an intercalated surfactant bilayer", J PHYS CH B, 105(32), 2001, pp. 7639-7650

Abstract

The cationic surfactant cetyltrimethylammonium (CTA) has been ion-exchangeintercalated from an aqueous solution of the surfactant by a two-step process into the galleries of layered cadmium thiophosphate to give cd(0.83)PS(3)(CTA)(0.34). Two phases of the intercalated product are observed. One is a phase characterized by a lattice expansion of 26.5 Angstrom, in which themethylene chains of the CTA ion adopt a tilted bilayer arrangement. This phase, when left in the reaction media, transforms to a phase characterized by a lattice expansion of: 12.5 Angstrom with no change in chemical stoichiometry. Using X-ray diffraction and orientation-dependent infrared spectroscopy, it has been possible to establish that the observed collapse of the Interlayer spacing is a consequence of the interdigitation of the methylene "tails" of the intercalated CTA ion. Infrared, Raman, and C-13 NMR spectroscopies have been used to establish the conformation of the methylene chainsin the intercalated normal bilayer and interdigitated bilayer phases of Cd0.83PS3(CTA)(0.34) and the dispersion of the delocalized methylene wagging (nu (3)) and rocking-twisting (nu (8)) modes as a probe of the planarity ofthe chains. The results indicate that a majority of the methylene chains in the intercalated interdigitated bilayer adopt an all-trans planar conformation, whereas, in the normal bilayer phase of Cd0.83PS3(CTA)(0.34), although a majority of the methylene units are in a trans configuration, the presence of a few gauche defects is sufficient to destroy the planarity of the methylene chain. Planarity of the methylene chains is the key factor for the absence or occurrence of interdigitation of the intercalated surfactant bilayer.

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Documento generato il 25/01/20 alle ore 01:15:58