Colloidal Particle Structures at Liquid Interfaces
- Event time: 1:00pm
- Event date: 3rd September 2007
- Speaker: Tommy Horozov (University of Hull)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
Phenomena related to solid particles trapped at fluid interfaces by interfacial tension forces are a subject of considerable attention, not least because of the relevance to various processes such as the stabilisation of emulsions, foams and fluid bicontinuous structures by particles and to the preparation of new materials. We study the behaviour of monodisperse silica particles at oil/water and air/water interfaces by microscope observations. Particles of different sizes and/or hydrophobicity and their mixtures are spread at the liquid interface to give one- or two-component particle monolayers. It is found that the structure of one-component monolayers strongly depends on the particle wettability. Very hydrophobic particles are well ordered in triangular lattices at very large interparticle distances (up to ~20 particle diameters) due to a strong long range repulsion through the oil (air). In contrast, a weak repulsion between hydrophilic particles is found. The repulsion is mediated mainly through the water and one-component hydrophilic particle monolayers are disordered and aggregated. Binary mixtures of large and small very hydrophobic particles form two-dimensional super lattices with different structure depending on the composition. The possible reasons for the very long-range repulsion between hydrophobic particles are discussed.
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..