ALKYLDIMETHYLAMINE OXIDE/ALKYL SODIUM-SULFATE ACTION, INTERACTION AND SOLUBILISATION (CARBON-13 NMR, MONOLAYER, MICELLE, MICROEMULSION, DUPLEX FILM).
Item
-
Title
-
ALKYLDIMETHYLAMINE OXIDE/ALKYL SODIUM-SULFATE ACTION, INTERACTION AND SOLUBILISATION (CARBON-13 NMR, MONOLAYER, MICELLE, MICROEMULSION, DUPLEX FILM).
-
Identifier
-
AAI8601630
-
identifier
-
8601630
-
Creator
-
CHANG, DAVID LUNGPAO.
-
Contributor
-
Henri L. Rosano
-
Date
-
1985
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Chemistry, Physical
-
Abstract
-
Alkyldimethylamine oxide (C(,x)DAO) aqueous solutions alone and in combination with alkyl sodium sulfate have been investigated as model surfactant systems. At any pH the amine oxide is in equilibrium with its protonated form. The solution viscosity depends strongly on the degree of ionisation ((beta)) with a maximum at (beta) = 0.5 due to formation of elongated structures. At high and low pHs spherical micelles are present with low solution viscosity. C-13 nmr reveals downfield chemical shifts for all carbons upon micellisation, and is attributed to the rotational isomerisation about the C-C bonds (gauche to trans), reflecting a more extended conformation of the chains in the micelle which maximises paraffin-paraffin interactions. Ionisation of the head group causes upfield shift of the first 3 carbons in the chain due to increased water penetration into the micelle with increasing cationic character. Monolayers of the C(,18) homolog show that the nonionised amine oxide produces a more expanded film and that minimum film expansion and maximum surface potential are obtained for (beta) = 0.5, suggesting closer packing because of hydrogen bonding. Progressive addition of SDS to C(,12) or C(,14)DAO leads to pH and viscosity increases and the maximum is reached at 3C(,x)DAO/SDS molar ratio, while lowest surface tension is observed in the equalmolar mixture. The C(,16) or C(,18)DAO/SDS mixtures are turbid with filament formation when the amine oxide is in excess. Their difference in behaviour, which illustrates the importance of chain compatibility, is attributed to the adsorption of protons on the micelle surface in the former, and protonation of amine oxide leading to complex formation occurs in the latter. When the solution is sufficiently acidic, precipitation of a 1:1 complex takes place for the compatible chain mixtures. Mixed monolayers of the C(,18) homologs show marked contraction at all subsolution pHs, indicating strong interaction between these species. Addition of an oil to the 1:1 mixed monolayer causes film expansion, provided that the chain lengths match, such that optimum penetration by the oil into the film is achieved. In some cases an increase in the collapse pressure is also observed, indicating greater stability of the film. This phenomenon can be treated as a restriction in the duplex film model for the formation of microemulsion.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
-
Program
-
Chemistry
