Details of Grant 

EPSRC Reference:	EP/D07214X/1
Title:	Colloidal Particles at Fluid Interfaces: Interactions and Applications for Novel Materials and Microfluidic Devices
Principal Investigator:	Horozov, Dr TS
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department:	Physical Sciences
Organisation:	University of Hull
Scheme:	Advanced Fellowship
Starts:	01 October 2006	Ends:	30 September 2011	Value (£):	477,105
EPSRC Research Topic Classifications:	Chemical Structure Complex fluids & soft solids Instrumentation Eng. & Dev.
EPSRC Industrial Sector Classifications:	No relevance to Underpinning Sectors
Related Grants:
Panel History:	Panel Date Panel Name Outcome 20 Apr 2006 Materials Fellowships 2006 - Interview Panel Deferred 31 Mar 2006 Materials Fellowships 2006 - Sift Panel Deferred
Summary on Grant Application Form
Small solid particles (1000 times smaller than a pinhead) have various applications as fillers and stabilisers in a range of industrial products and as building blocks of different materials and devices used in optics and electronics. Many of their applications utilise the ability of these particles to stay firmly attached to oil-water interfaces, thus forming particle monolayers. Interfacial particles are partially immersed in both liquids. The water liking particles (called hydrophilic) are largely immersed in the water, while the oil liking ones (called hydrophobic) are mainly immersed in the oil. It was found recently that the behaviour of hydrophilic and hydrophobic particles at the oil-water interface is very different. Hydrophilic particles attract each other making particle rafts. In contrast, the hydrophobic particles strongly repel each other and stay well separated at large distances in ordered arrays. It has been shown that the repulsion between hydrophobic particles is caused by electric charges at their surface in contact with the oil. However, the important questions about the origin of these charges and how they depend on the chemical nature of particles and oil are still open. The situation became even more puzzling after very recent findings which suggested that the same electric charges might be responsible for long range particle attraction. In addition, strange selective attraction between hydrophobic and hydrophilic particles has been observed in their mixed monolayers. Hence, many aspects of the interactions between particles at oil-water interfaces are still controversial and puzzling. One of our aims in this research is to investigate the interactions between solid particles at oil- water interfaces in order to reveal the factors and mechanisms responsible for the surface charge at the particle-oil interface. To clarify these aspects is of significant scientific and practical importance.Solid particles can also attach to the surface of droplets when oil, water and particles are stirred together. The obtained particle-stabilised emulsion can be extremely stable (for years!) because particle armoured droplets cannot merge. This is their best asset which makes these emulsions useful for preparation of durable cosmetics and other products. However, we will not focus on this traditional application of particle-stabilised emulsions. Instead, we will use them as a tool to develop methods for fabrication of novel materials and devices with interesting and useful properties. Our research strategy is based on the following experimental facts: (i) particles are strongly (irreversibly) held at the drop surface staying partially immersed in the drop; (ii) particles can form an incompressible porous membrane around the drops, preserving the droplet area when the drop volume is decreased; (iii) particle stabilised droplets can be firmly connected to each other when some solid particles become simultaneously attached to the surface of two separate droplets. The latter occurs spontaneously in some emulsions. We will take an advantage from these unique features of particle-stabilised emulsions by using them in a non-traditional way in order to develop experimental methods and procedures for fabrication of so-called Janus particles whose two halves have very different properties (for instance hydrophilic and hydrophobic), unusual emulsions with non-spherical shape of their droplets, non-spherical composite solid particles, porous materials with controllable structure and composition, etc.
Key Findings
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Organisation Website:	http://www.hull.ac.uk