Light scattering studies on the polymerisation and solubilization in detergent solutions

Robb, Derek J. M (1964) Light scattering studies on the polymerisation and solubilization in detergent solutions. PhD thesis, University of Glasgow.

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The thesis has been presented in two parts:- Part I. Many previous attempts have been made to measure the size of light scattering techniques. The principal difficulties encountered in this analysis are (1) the impossibility of measurement at concentrations below the critical micelle concentration (C.M.C.) due to dissociation of the micelles, (2) the ionic nature of the micelles and (3) the possibility that the degree of aggregation of the micelles does not remain constant as the concentration is varied. Instead of applying present theory, which involves some uncertainties, the suggestion was made that it may be possible to modify the micelles in such a way as to eliminate some of the difficulties and allow for a more concise analysis. This could be achieved by utilizing unsaturated soaps such as sodium oleate CH3(CH2)7CH=CH(CH2)7 COONa+, undecenyl trimethyl ammonium bromide (U.T.A.B.) CH2=CH(CH2)9N(CH3)3+Br and sodium undecenyl sulphate (S.U.S.) CH2=CH(CH2)9OSO3-Na+. By causing polymerisation of the double bonds of the molecules in each separate micelle a 'polymicelle' may be obtained. A solution containing such 'polymicelles' would escape difficulties (1) and (3) while case (2) could be overcome for the carboxylic soaps by acidification after polymerisation and extraction of the polycarboxylic acid by organic solvents in which light scattering measurements could also be performed. The possibility that polymicelles as envisaged above, could be formed with sodium oleate containing solubilized styrene is thwarted by the formation of a long chain polysoap, vastly different in size from the original micelle. The styranaoleate co-polymers (formed by irradiation with U.V. light and using azobisisobutyronitrile (A.B.I.N.) as initiator) have molecular weights dependent upon the styrehe concentration. The break in the Av's curves (denoting the C.M.C.) is eliminated with solutions of S.U.S. after irradiation and light scattering by the soap can be detected below the C.M.C. of the unirradiated soap. This indicates that there are few dissociable micelles left in solution. Measurements of (dn/dc)u electrolyte have been made and used in final analysis in preference to the (dn/dc)c electrolyte values employed by previous investigators in determining micellar weights in dilute salt solution. Evaluation of the refractive index increment at constant chemical potential of electrolyte involves dialysing soap solutions against respective salt solutions. This quantity cannot be determined for ordinary soaps as the micelles would simply dissociate and diffuse through the membrane. The polymicellar weight obtained for S.U.S., both measured directly and by exprapolation of the solubilized styrene measurements, are in the region of 13,500. The value obtained by conventional means is 30,800. The discrepancy between the two values can be accounted for by incomplete polymerisation of the micelles and the possibility that there is more than one polymerisation centre per micelle and termination is by disproportionation. With U.T.A.B. the polymicellar weight (12,750) is close to the apparent micellar weight of 13,300. This indicates that most, if not all, of the U.T.A.B. molecules within the micelles have polymerised together. (Abstract shortened by ProQuest.).

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: A J Hyde
Keywords: Polymer chemistry
Date of Award: 1964
Depositing User: Enlighten Team
Unique ID: glathesis:1964-73062
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56

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