The aqueous phase behavior of linear alkylbenzene sulphonate/polycarboxylate polymer systems

5^th World Congress on Physics

July 17-18, 2018 Prague, Czech Republic

M Hussain, M Nagaraj, O J Cayre, H Tantawy, E S J Robles and A E Bayly

University of Leeds, UK
Procter & Gamble Ltd, UK

Posters & Accepted Abstracts: J Laser Opt Photonics

Abstract :

Linear alkylbenzene sulphonate (NaLAS) surfactant, used in detergent products, is often combined with polycarboxylate polymers that act as anti-redeposition agents and viscosity modifiers. This work investigates the interaction of the polymer and surfactant in an aqueous system via a NaLAS-polyacrylate-water phase diagram at 50ºC. It shows the multiple effects the depletion flocculation phenomena have depending upon the region of the phase diagram being considered. 2H-NMR shows that the sizes of the multilamellar vesicle structures increase with polymer concentration. This is the first time that 2H-NMR has been used to probe the diffusion and anisotropy of D2O within the bilayers of the vesicles for such a system. The phase diagram, shown below, presents a micellar region at surfactant concentrations of up to 35 wt% NaLAS and a lamellar phase plus micellar region at higher concentrations, consistent with previous observations by Stewart1 and Richards2. As polymer is added at low surfactant concentrations, between 10 and 20 wt% NaLAS, a non-birefringent phase is observed; perhaps a polymer rich phase resulting from depletion flocculation. At high surfactant concentrations, a second lamellar phase is also induced, different in bulk density from the original, again likely resulting from depletion flocculation of multilamellar vesicles. 2H-NMR was used to determine an increase in average multilamellar vesicle size as a function of polymer concentration. The mechanism causing this is likely a result of vesicle fusion resulting from depletion flocculation caused by polymer addition, as initially described by van de Pas3.

Biography :

E-mail: ed10m5h@leeds.ac.uk