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Modifying the structure and flow behaviour of aqueous montmorillonite suspensions with surfactant

DOI: 10.1098/rsta.2012.0262 DOI Help
PMID: 23459964 PMID Help

Authors: Yannan Cui (University of Bristol) , Claire Pizzey (Diamond Light Source) , Jeroen Van Duijneveldt (University of Bristol)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Philosophical Transactions Of The Royal Society A: Mathematical, Physical And Engineering Sciences , VOL 371 (1988) , PAGES 20120262 - 20120262

State: Published (Approved)
Published: March 2013

Abstract: Colloidal suspensions of plate-like particles undergo a variety of phase transitions. The predicted isotropic/nematic transition is often pre-empted by a sol/gel transition, especially in suspensions of the most commonly used natural swelling clay montmorillonite (MMT). A number of factors, including charge interactions, flexibility and salt concentration, may contribute to this competition. In this study, the effect of surfactant adsorption on suspensions of MMT was studied using rheology, small-angle X-ray scattering, static light scattering and optical microscopy. The addition of a polyetheramine surfactant reduced the moduli of the system and shifted the sol/gel transition to a much higher clay concentration, compared with suspensions of bare clay particles. Yet, scattering data revealed no change in suspension structure on length scales up to around a micrometre. Primary aggregates remain at this length scale and no nematic phase is formed. There is, however, a change in structure at large length scales (of order 20??m) where light scattering indicates the presence of string-like aggregates that disappear on addition of surfactant. Microscope images of dried suspensions also revealed a string-like structure. The dried strings show strong birefringence and may consist of concentric cylinders, self-assembled from clay sheets

Journal Keywords: Clay; Surfactant; Liquid Crystal; Rheology; Scattering

Subject Areas: Chemistry


Instruments: I22-Small angle scattering & Diffraction