1. Water Interactions with Calcium Carbonate Nanoparticles and 2. Catching up on Bijels
- Event time: 1:00pm
- Event date: 8th December 2008
- Speaker: Joe Tavacoli (Formerly School of Physics & Astronomy, University of Edinburgh)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
The presence and effect of water on calcium carbonate nanoparticles used in engine additives, stabilized with a sulfonate surfactant, is investigated using small-angle neutron scattering, dynamic light scattering, Fourier transform infrared spectroscopy and rheometry. These techniques provide complementary data that suggests the formation of a layer of water around the core of the particles ensuring continued colloidal stability yet increasing the dispersion viscosity. Through the use of small-angle neutron scattering, the dimensions of this layer have been quantified to effectively one or two water molecules in thickness. The lack of a significant electrostatic repulsion is evidence that the water layer is insufficient to cause major dissociation of surface ions.
PART 2 Catching up on Bijels
Bicontinous interfacially jammed emulsion gels (Bijels) are a new class of soft materials which were theoretically described (1) in 2004 and experimentally verified in 2007 (2). Such gels consist of two immiscible liquids, separated by interfacially positioned colloidal particles that afford each liquid unbroken ?pathways? throughout the structure. As such, the structure is said to be bicontinous. This bicontinuity coupled with the Bijel's high interfacial area has led to speculation that the Bijel could have numerous industrial applications, such as in solvent extraction and catalysis. The first Bijel comprised of water, lutidine and fluorescein isothiocyanate (FITC) tagged silica. This system is now well established and here we present some novel systems. Unlike the water-lutidine system these are stable at ambient temperature.
(1) Stratford K, Adhikari R, Pagonabarraga I, Desplat J-C and Cates M E 2005 Science 309 2198
(2) Herzig E M, White K A, Schofield A B, PoonW C K and Clegg P S 2007 Nat. Mater. 6 96
This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..