Physico-chemical studies on solutions of synthetic non-ionic detergents

Florence, Alexander Taylor (1965) Physico-chemical studies on solutions of synthetic non-ionic detergents. PhD thesis, University of Glasgow.

Abstract

This thesis deals with an investigation into the properties of aqueous solutions of non-ionic detergents of the polyoxyethylene mono-alkyl ether clans, and comprises of an introductory and an experimental section, part I and part II respectively. Part I contains a review of previous work on the synthesis and purification of homogeneous non-ionic detergents and on their solution properties. The theoretical basis of micelle formation is then treated and a section is devoted to the structure and strozWring of waters as this is an important factor in micelle formation. Considerable interest has recently been shown in the thermodynamics of micellisation of non-ionic detergents, and the work done to date on this topic is discussed. The penulmate section of the Introduction deals with aqueous non-electrolyte solution with particular reference to hydration and its effect on solute activity concentration relationships. The theory of the techniques used in the investigation (surface tension, light-scattering, viscosity and vapour pressure techniques) is dealt with briefly, and concludes part 1.This thesis deals with an investigation into the properties of aqueous solutions of non-ionic detergents of the polyoxyethylene mono-alkyl ether clans, and comprises of an introductory and an experimental section, part I and part II respectively. Part I contains a review of previous work on the synthesis and purification of homogeneous non-ionic detergents and on their solution properties. The theoretical basis of micelle formation is then treated and a section is devoted to the structure and stroring of waters as this is an important factor in micelle formation. Considerable interest has recently been shown in the thermodynamics of micellisation of non-ionic detergents, and the work done to date on this topic is discussed. The penulmate section of the Introduction deals with aqueous non-electrolyte solution with particular reference to hydration and its effect on solute activity concentration relationships. The theory of the techniques used in the investigation (surface tension, 1ight-scatteriDg, viscosity and vapour pressure techniques) is dealt with briefly, and concludes part 1. The effect of branching the hydrocarbon chain of non-ionic detergents was studied by synthesising a new series of branched-hydrocarbon, chain compounds of general formula, R20CH0CH2(OCH2(H2)n0H with n = 6 or 9 and R 7-1 Olin 9 C2H5D nc-C3H7p WA1/4110 0 Three straight chain compounds were also prepared for comparative studies, these being CH3(CH2)(OCH4H2)110H with = 1. 3 and 5 and n = 6. The surface chemistry of these compounds in aqueous solution was studied at three temperatures. The temperature variation of the critical micelle concentration yielded the enthalpies and entropies of mieellisation by the use of an equation of the Clausius-Clapeyron type. High critical micelle concentrations were evident in some of the systems, and this afforded an opportunity of studying ;ire-t icellar behaviour. Viscosity and vapour pressure measurements gave an indication or the hydration of the detergent monomers and of the polymethylene glycols. Viscosity measurements on micellar solutions yielded hydration values for the micelles, and an increase in hydration of the glycol portion of the monomers was indicated on micelle forwtion. The positive entropy values may be explained by the loss of water structure around the alkyl chains ao they enter the micelleo. Micellar sizes and aggregation numbers were obtained by light-scattering, but the smallness of the micelles precluded any inference am to their shape being drawn from the data. it was concluded, however, that the micelles were in general, symmetrical but for those formed by the detergent, (04H9)20H.GR(0012CH2)6011 which, on interpretation of viscosity measurements and Hugginsl constants,were assumed to become asymmetric as the temperature of the system was raised. Vapour pressure stadies on aqueous solutions of three glycols ( with 6 9 and 12 ethylene oxide mut) showed a negative deviation from Raohlt,e Law, interpmtable in the caul of the first two glycols on the basis of hydration. Other explanations of the deviation of solute activity from ideal behaviour were tested and the results discussed. Similar measurements were also made on three detergent gystams. It was shown that the activity of the detergent increased above the critical micelle concentration, in agreement with the behaviour predicted by the Law of Mass Action approach to micelle formation, although at variance with the predictions of the pseudo-phase approach.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: P H Elworthy
• Keywords: Physical chemistry
• Date of Award: 1965
• Depositing User: Enlighten Team
• Unique ID: glathesis:1965-72682
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 11 Jun 2019 11:06
• Last Modified: 11 Jun 2019 11:06
• URI: https://theses.gla.ac.uk/id/eprint/72682