RA5a: Structure,environment and staffing policyThis submission is based on research carried out in the School of Applied Sciences under the umbrella of Materials Surfaces, the main themes are: Surface Analysis, Surface Engineering, Adsorption and Catalysis. These areas were identified for strengthening in a post-1996 strategic review of scientific research after which two new Chairs in Materials were established: in 1997 Iain Baikie was promoted to Professor of Applied Physics for his work on surface work function and the scanning Kelvin probe and Robert Bradley joined the School, from The Institute of Surface Science & Technology at Loughborough University, as Professor of Materials Chemistry. Recruitment of Dr Alex Shard, who joined the surface chemistry group from the IRC in Surface Science, and Dr Paul Campbell to the physics group to work on scanning probes/nano-technology, further strengthened the group. In addition to academic staff recruitment, a substantial commitment and investment (>£0.5m) has been made by the University to upgrade facilities. As a result of this, the equipment and laboratories that service the relevant work are of the highest standards.
The submission is small and highly focused in the areas of molecular and nano/micro structural properties of Surfaces and Interfaces and their effects on macroscopic behaviour in a small range of materials systems. The output as assessed by peer review is of high quality and the workers returned here are well supported by grant income and publish their findings in the most prominent and highly regarded international materials/physical science journals. The volume of work referenced in this document is necessarily low but a significant output exists besides those publications listed e.g. www.\rgu\msig.
Professor Bradley (RHB) and Professor Baikie (IB) have strong international reputations based on visiting positions and collaborations with EU and US universities and corporations and have wide UK and international funding bases. Dr Shard (AS) has a strong reputation for fundamental work in Surface Science techniques (SEXAFS, NIXSW and Surface XRD) and has developed a range of national and international collaborations in these areas as well as winning substantial OST funding for surface science and biomaterials work. Dr Campbell (PC) was extremely active in the development of scanning probe microscopy and in nano-technology having secured funding from the Royal Society and Nuffield Foundation and worked with a number of UK establishments and international instrument manufacturers.
RHB et al have developed chemical force microscopy (CFM) to obtain surface chemical, frictional and energetic information. The main thrust of this has been the use of silane based surface coating techniques to chemically functionalise AFM probe tips with specific end groups and to use these probes to study chemically engineered polymer surfaces [PC1]. By combining this approach with X-ray photoelectron spectroscopy data a new model which allows prediction of surface oxygen levels and reactivity (water contact angle and polar free energy) has been developed [RHB1]. Sub-micron chemical imaging of chemically heterogeneous polymer surfaces has been demonstrated using test substrates produced by spin-casting phase separable polymer blend films with chemically distinct features [RHB2][RHB3].
Surface modification using plasmas, ozone, flame, corona etc. to promote adhesion and wettability is a major feature of industrial polymer usage. We have developed the techniques of XPS and AFM to study the chemical, physical and mechanistic routes that constitute surface modification. We have studied structural and functional polymers and identified mechanisms of chain oxidative cleavage which result in the formation of low molecular weight oxidised material as a function of oxidation levels, the fluid like nature of this material, and it's surface tension lead to flow and accretion resulting in topographical changes. This has led to a short series of papers in high quality journals [such as PC2] and a greater understanding of some of the surface properties which determine adhesion to polymer surfaces.
RHB et al are investigating the surface engineering of polymers and metals for biomedical device applications (previous CASE award Smith & Nephew). Recent work has shown that untreated polystyrene has very poor attachment and growth properties for soft tissue culture purposes. Grafting surface oxygen functional groups onto the PS leads to more rapid cell attachment and improved growth [RB4]. A treatment method to produce tissue culture grade polystyrene from standard low-cost material has been patented. This has led to a partnership with the orthopaedic divisions of Grampian University Healthcare Trust to engineer soft tissue, bone and cartilage materials for reconstructive surgery and to modify the interactions between bone and metal/ceramic surfaces in order to extend the lifetime of joint implants (with Smith & Nephew and Stryker UK).
RHB is working on the photosensitisation of textile fibre surfaces using ultra violet/ozone to manipulate the kinetics of dye adsorption and desorption. He has already received substantial income for work in this area from the UK wool industry (The Woolmark Company £20K and CSIRO Australia £140K) and a body of literature has resulted.
AS has a track record in surface analysis of biopolymers [AS1] and has recently collaborated with RHB in the areas of polymer surface modification/biocompatibility for soft tissue culture applications. EPSRC funding to study plasma patterning of polymer surfaces for controlled cell attachment has recently been won (£65,000). In addition AS has considerable expertise in the area of catalysis where his work on the structure of adsorbates on single crystal surfaces has been recognised by the award of synchrotron radiation beam time worth over £330,000 from CLRC in peer reviewed submissions over the past three years. From these investigations his work on iodine on Pd (111) using standing wave absorption has shown the sites of adsorption to be the three-fold fcc hollows [AS2]. SEXAFS studies of chlorine on Pd(111) have allowed computation of the Cl-Pd bond length and given information regarding the surface structure of the adsorbed states as a function of coverage [AS3]. The adsorption of chlorine on silver has been studied at low temperatures and the established understanding of this system completely revised. His J.Phys.Chem paper on this work was regarded as „presenting extremely important results…which generally tidy up a lot of loose ends in the field“ by the referees.
RHB has a longstanding collaboration with MOD/DERA in the area of vapour adsorption and purification which has resulted in a stream of publications on porosity characterisation relating to physical adsorption of organic vapours. This has been extended to include consideration of the surface chemical interactions of carbons for adsorption and catalysis purposes and two funding awards have been made by DERA in recognition of novel achievements in this area. Currently work with CBD/DERA Porton Down focuses on a new generation of breathing apparatus filter materials for military use (£47,000).
EPSRC funding (£72,000) has also been obtained to study specific interactions within the pores of polymer based carbons and work has been published on molecular sieve carbons produced from polyaramid fibres. This has shown that aliphatic, aramid, nitrogen undergoes rearrangement to aromatic quaternary structures during carbonization, the associated photoelectron binding energy shift data has been reported as have the C-N aromatic bond lengths and angles. This work is ongoing and Bradley and Shard have been awarded CLRC synchrotron beam time of value £30,000 to study physical and chemical rearrangements which occur during polymer carbonization in what was noted by the CLRC committee as an "interesting and highly rated proposal". Very recent studies of the use of active carbons surface chemistry for the selective removal of toxic species such as heavy metals and organic species from water sources has generated interest from commercial and military carbon users. Adsorptivity of aqueous metal ions such as Cu2+ has been shown to increase as a function of surface oxygen level (controlled using an O2/O3 fluidised bed) whilst the adsorption of aromatic hydrocarbons decreases – individual mechanisms of adsorption have been proposed. These methods are being used to enhance the adsorptivity of active carbons toward water borne pollutants, the work is being partly supported by Westvaco Carbon Corp. Charleston SC and is under-pinned by a chemical and thermodynaic modelling - a series of journal papers has resulted.
IB has developed the UK’s first UHV High Resolution Scanning Kelvin Probe (SKP) incorporating surface tracking [IB1,IB2] which has been applied to a range of surface phenomena including semiconductor quality control, hyperthermal surface ionisation, surface photovoltage spectroscopy and surface photoelectric emission under a JREI initiative with DERA matching funding. The project has been co-funded by Royal Society (£10,000) and EPSRC/SPMI (£65,000), EPSRC/Electronic Materials (£12,000). The final EPSRC SPMI report was awarded alpha 5 „Highly significant contribution to the field“ with excellent management of resources. Indeed all EPSRC projects held by Prof. Baikie have achieved a minimum of alpha 4 for scientific/technical merit. Ambient and vacuum versions of the device have been developed and have recently featured in the Nov 2000 edition of „Vacuum Solutions“ (IOP publishing). Application of the Vacuum version include in-situ profiling of high and low work function surfaces as suitable targets for hyperthermal surface ionisation (a novel very high resolution gas analysis technique) funded by DERA/JREI (£60,000) and £35,000 of additional DERA monies from the anti-terrorist unit at Fort Halstead. In collaboration with Prof. Cahay, Department of Electronic Materials, University of Cincinnati, USA, the performance of (stable) very low work function surfaces (< 2.1 eV) for microwave switching applications have also been studied. Data have been published on the initial oxidation of semiconductor surfaces, including Si(111), Si(100) and surface preparation techniques [IB3] and recently, in the J. Appl. Phys., a procedure to permit absolute work function/surface potential measurements from this hitherto relative technique has been published. Usage of the SKP has been extended to aid the detection of low level metal impurities via Deep Level Transient Spectroscopy and Surface Photovoltage Spectroscopy. Baikie et al have conducted a study of 2 and 3 D contamination in industrial quality silicon wafers funded by EPSRC (Analytical Sciences) and was performed in conjunction with IMEC (Belgium) and AEA Technology PLC (Harwell). This work and that of the other research projects have been published by Baikie et al in the journals Surface Science and Thin Solid Films and presented at the Spring MRS, 1998,2000, Fall AVS 2000. In the former conference we were awarded one of the 4 major poster prizes from among the circa 2000 entries.
In conjunction with the Biocurrents Research Center, Woods Hole, Mass., USA we have developed the worlds first multiple tip scanning Bio-Kelvin probe. This work, published in Review of Scientific Instruments, indicates that the SKP technology can be used to measure bio-potentials due to photo- and geo-tropism in plants and human wounding potential in the cornea of the eye and in the epidermis [IB4]. Work continues with BRC, Woods Hole, MD’s in the New England Medical Centre, Boston, USA., Prof. Peder Estrup, Dean of Research, Brown University, Providence USA. The plant investigations will continue via Prof. Porterfield, Department of Biological Sciences, University of Missouri-Rolla and have been submitted for NASA and NIH funding. The SKP technique has been applied in collaboration with Dr. F. Cacialli (from Prof. Friends Group at Cambridge University) to investigate ITO and Semiconductor polymers and the results published. We have hosted scientists from Univ. of Ulster (Defect Density of Si and GaAs Technologies), Universitiet des Bundeswhehr (Catalytic activity in nobel metal fuel cells), and conducted survey scans for Surrey University (ITO), Cambridge Display Technology Ltd (ITO), DERA (DLC), Thin Solar Films (Hahn-Meitner Institute, Berlin), Mupor Ltd (coated microporous membranes). To correlate work function changes occurring at the outer layers of materials with geometrical effect we have performed in-situ SKP and STM in collaboration with Prof. J. Behm’s group in the Department of Surface Chemistry and Catalysis at Ulm University, Germany. The principal outcome of this work, which has been published, is the ease with which surface reaction mechanisms can be mapped out initially with SKP, allowing STM to be performed at selected relevant points in , e.g., an adsorption, experiment.
Environment: Facilities Since 1996 existing Auger electron spectroscopy and electron diffraction facilities have been upgraded and Scanning Kelvin Probe and BioKelvin Probe facilities developed by external and internal investment (EPSRC, industrial, University Educational Development Trust and University Research Funds). In addition new laboratories for materials surfaces and interfaces studies have been established which house monochromated, imaging X-ray photoelectron spectroscopy (Kratos 5 channel Axis); scanning probe microscopy (Digital Instruments Nanoscope III); adsorption/catalysis equipment (Hiden IGA) and immersion calorimetry (Setaram C80). Mechanical, NDT and acoustic emission facilities have also been upgraded. A total of £0.5m (obtained from the University Educational Development Trust and Capital Equipment Fund) has been spent since the last RAE. Investment has been extremely high and the groups have state-of –the-art facilities to support the specific studies in materials surface and interfaces and related macro-properties, which they undertake.
Research Ethos Our objective in establishing a small high quality research grouping is to provide niches of postgraduate and postdoctoral research excellence. We recognise the inclusive nature of Materials Science and the sub-areas in which we operate. Outside the main expertise of our own staff we continually find new areas to which we can apply the techniques and approach that we have developed. This has led to a wide range of international collaborations with other materials groups working in both EU countries and with the US. Each year a substantial number of undergraduate third and fourth year BSc honours students undertake research projects within materials. We also accept students from the French Universities of Limoge and Lannion who wish to undertake a period of study abroad under programmes such as Erasmus and Tempus.
Research Management Materials research takes place within the School of Applied Sciences. RHB is the overall research co-ordinator for the School and also takes specific responsibility for Materials Science. The University runs a vigorous staff development programme, which includes instruction for new researchers in supervision, funding application and project management. All staff are expected to undertake research in their relevant fields. An in-School staff-mentoring scheme is in operation to allow staff to develop their academic skills and interdisciplinary research is positively encouraged
Staffing Policy Where recruitment has been possible, this has been carried out to strengthen the existing expertise in surfaces and interfaces. This approach will continue in order to reinforce and widen our expertise.
Copyright 2002 - HEFCE, SHEFC, ELWa, DEL
Last updated 17 October 2003