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Title
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SURFACE CHEMISTRY: FUNDAMENTAL THERMODYNAMIC AND SURFACE PROPERTIES OF HIGHLY PURIFIED MODEL SURFACTANTS. ELUCIDATION OF INTERRELATIONSHIPS BETWEEN SURFACTANT CHEMICAL STRUCTURE, MECHANISMS OF ADSORPTION, AND PROPERTIES OF IMPORTANCE IN PRACTICAL APPLICATIONS.
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Identifier
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AAI8508692
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identifier
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8508692
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Creator
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DAHANAYAKE, MANILAL.
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Contributor
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Milton J. Rosen
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Date
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1985
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Physical
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Abstract
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The interrelationships between surfactant chemical structure, mechanism of adsorption, and properties of importance in practical application for well purified, well characterized surfactants of all charge types are elucidated. Properties measured are critical micelle concentration (cmc), maximum surface excess concentration and minimum area per molecule at aqueous solution/air interface, efficiency and effectiveness of surface tension reduction, standard thermodynamic parameters of micellization and of adsorption, effectiveness in foaming and textile wetting time.;Anionic surfactants of homogenous structure, C(,12)H(,25)(OC(,2)H(,4))(,x)OH, where x = 2-8, were investigated. The standard free energy of micellization was found to increase with increase in the length of the oxyethylene chain. On the other hand, the effect of this change on the standard free energy of adsorption was found to be almost insignificant.;Of the two cationic surfactants, N-dodecylpyridinium bromide was found to be somewhat more surface active than the corresponding chloride in all properties investigated. The difference appears to be due to the greater degree of hydration of the chloride ion compared to the bromide. Micellization appears to involve more dehydration of the counterion than adsorption at the aqueous solution-air interface.;Zwitterionic surfactants of structure, RN(CH(,2)C(,6)H(,5))(CH(,3))CH(,2)COO('-), where R is an alkyl chain of 10 or 12 carbon atoms, and RN(CH(,2)C(,6)H(,5))(CH(,3))CH(,2)CH(,2)SO(,3) where R is 8, 10 and 12 carbon atoms, were synthesized. The surface areas per molecule for the glycines are comparable to those of the corresponding N-alkyl,N,N-dimethylglycines and 2-(trimethylammonium)alkanoates. On the other hand, the cmc for the glycines are found to be considerably smaller than for the corresponding N-alkyl,N,N-dimethylglycines and 2-(trimethylammonium)alkanoates.;Two series of anionic surfactants of type C(,12)H(,25)(OC(,2)H(,4))(,i)OSO(,3)Na, where i = 1 and 2, and C(,n)H(,2n+1)(OC(,2)H(,4))(,i)SO(,3)Na, where i = 0 or 1, and n = 10 and 12 were investigated. In contrast to the polyethenoxylated nonionics, increases in the negative standard free energies of micellization and adsorption were observed with introduction of oxyethylene units into both these types of compounds. The complexation of the counterion with the oxyethylene groups of these polyethenoxylated anionic surfactants is suggested as an explanation for these results.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Chemistry
