Below is a list of titles and abstracts from current or very recently expired grants with various bodies.
Structure and activity of phospholipases at membrane surfaces (1/4/2003-31/3/2006 £242k)
Neutron reflection and ellispometry will be used to follow the evolution of the structure and composition of phospholipid bilayers and monolayers during attack by phospholipases and lipases. The overall objective will be to elucidate the local mechanisms of interfacial enzyme reactions. This can be divided approximately into the following subsidiary objectives: (i) to identify the main structural changes occurring during the basic mechanism of interfacial catalysis and to correlate these between different chemical situations, (ii) to obtain structural and kinetic information about the mechanism of catalysis at a higher level than presently accessible, with a focus on the specific details for phospholipase PLA2, and (iii) to explore parallels in the behaviour of other phospholipases and possibly to a lipase.
Current EPSRC Support
Chemistry/function relationships at interfaces in soft condensed matter (1/10/2001-30/9/2002 £82k)
Functional characteristics of materials are to a large degree determined by the properties of material surfaces and their interactions with the ambient media, which has the consequence that such properties as wetting, adhesion, and friction, can be manipulated by the introduction of molecular-size surface layers. The proposal aims to explore this linkage along the following lines: (i) To examine new possibilities for material surface design by exploiting the potential of using novel methods of depositing thin films at surfaces by, for example, co-adsorption and sequential adsorption strategies; (ii) The elaboration of experimental methods for studying the interfacial properties of thin adsorbed layers with a focus on enhancing the complementarity of ellipsometry, neutron reflectometry and atomic force microscopy; (iii) The development of theoretical models for predicting dynamic adsorption and surface ordering phenomena in adsorbed layers and thin surface films; (iv) The improvement of our empirical and theoretical understanding of chemistry-topography-function relationships for thin surface films, where function refers principally to adhesion, friction, and wettability.
The structure and composition of polymer/surfactant mixtures at interfaces (1/6/2001-30/11/2004 £1166k)
Surfactant/polymer mixtures are used in a wide range of formulations because the combination of the two leads to a wide variety of useful rheological and surface properties. The former have been relatively well studied, but the latter hardly studied at all. The difficulty has been the lack of suitable experimental techniques. Neutron reflection is sensitive to interfacial composition and structure and the complexity of the interfaces of polymer/surfactant mixtures in no way diminishes this sensitivity. We have already demonstrated that neutron reflection is able to reveal an unexpected level of interesting detail in these mixed layers. We now propose to make a systematic study of the interfacial composition and structure of representative types of surfactant/polymer mixture and to relate this molecular level information to the thermodynamic aspects of the surface behaviour. We will focus on the air/water interface because we will be able to achieve a much higher precision of measurement and interpretation and therefore have a significant chance of producing a quantitative model. However, we are aware that, in terms of applications, the behaviour at the solid/liquid interface is more important and we will be seeking to extend the model to this more difficult surface.
The mixing of surfactants at interfaces (19/4/1999 - 18/10/2002 £616k)
For the first time we have an experimental technique, neutron reflection, that can determine the composition and key structural parameters of surfactant mixtures adsorbed at interfaces. We propose to use the technique for a thorough study of four systems which would form the basis of a predictive model, more soundly based than any presently available.
Interactions of proteins and surfactants at the solid/liquid interface (J.R.Lu (UMIST) the principal investigator, 1/10/2001-31/3/2002 £70k)
Neutron reflection combined with deuterium labelling offers the best means for tackling the complexity of the interaction of protein and surfactant at the solid-water interface. The adsorption and structural distributions of a range of food and blood proteins at the solid-water interface will be studied and their subsequent removal from a range of solid substrates will by investigated by using surfactants of different structural type. The surface properties will be controlled by chemically grafting monolayers with different functional groups on the outer surface. The effect of system conditions, e.g. pH, salt and protein concentrations in bulk solutions on the ease of protein removal from the solid substrates will be quantified.
Recent past EPSRC Support
Adsorption from solution at functionalized solid surfaces (1/1/1998-31/8/2001 £636k)
Neutron reflection will be used to give molecular level information about layers of amphiphiles (including)proteins) adsorbed at the solid / liquid interface. Interfaces with a range of surface functionality, some to mimic the surfaces of important technological materials, will be prepared using self-assembly techniques and in situ chemistry. To enhance the sensitivity of the neutron experiment the self-assembled monolayers will be partially and selectively deuterated.
The structure of surfactant layers at the air/water interface (1/1/1998-30/9/2001 £551k)
For the first time we have an experimental technique, neutron reflection that can determine the main structural parameters of surfactactant layers adsorbed at the air/liquid insert interface. We propose to use the technique to study a selection of surfactants representative of the different types used industrially, i.e. anionic, cationic, zwitterionic, non-ionic, etc., and to attempt to relate molecular structure of the layer to macroscopic behaviour.
ROPA: Characterization of clay/surfactant/oil complexes and the preparation of novel clay based materials (1/10/1996-30/6/2000 £51k)
The range of structures adopted by clay/surfactant/oil mixtures will be studied by X-ray and neutron diffraction using single crystal vermiculites as the clay material and isotopic labelling to locate the intercalated components. The understanding obtained will be used to optimise conditions for the synthesis of porous zeolite-like catalysts and polymer-clay composites.
ROPA: Time dependent behaviour of multicomponent mixtures at wet interfaces (1/4/1995-31/3/1996 £48k)
To develop and optimise experiments for studying the dynamics of adsorption in multi-component systems. To apply the techniques of netron reflection and sum frequency spectroscopy to study the time dependent structure and composition of wet interfaces.
The structure of wet interfaces (1/4/1994-30/9/1997 £165k)
To use neutron and x-ray reflection to determine the structure of layers adsorbed at air/liquid, liquid/liquid, and solid/liquid interfaces including the determination of ion distributions at charged interfaces.
Interactions of proteins and surfactants at the solid-water interface (J.R.Lu (University of Surrey) the principal investigator, 18/5/1998-30/4/2001 £469k)
Neutron reflection combined with deuterium labelling offers the best means for tackling the complexity of the interaction of protein and surfactant at the solid-water interface. The adsorption and structural distributions of a range of food and blood proteins at the solid-water interface will be studied and their subsequent removal from a range of solid substrates will by investigated by using surfactants of different structural type. The surface properties will be controlled by chemically grafting monolayers with different functional groups on the outer surface. The effect of system conditions, e.g. pH, salt and protein concentrations in bulk solutions on the ease of protein removal from the solid substrates will be quantified.