Surface Studies In Carbon Science and Materials Chemistry
Professor R.H. Bradley
Materials Research Centre
School of Engineering
The Robert Gordon University
Aberdeen, United Kingdom
Tuesday, November 28, 2006 3:00 pm
Ben Bandy Conference Center
UK Center for Applied Energy Research
Surface and interfacial properties influence the behavior of almost all Materials systems and understanding and controlling these properties is therefore critical in optimizing macroscopic behavior in practical applications.
In the first part of my talk I will give a brief introduction to the main research areas of my group. I will then give an overview of the main interatomic and molecular forces which determine physical interactions such as adsorption and adhesion and then go on to show how surface science and surface engineering methods can be used to study and control these types of phenomenon in a range of carbon based and other materials systems which are of practical and topical interest.
I will then illustrate how the quantitative analysis of equilibrium adsorption isotherm data can be combined with surface composition information, obtained from x-ray photoelectron spectroscopy, to explain the thermodynamic behavior of particulate carbon black surfaces. Changes in heats of immersion in different liquids will be shown to result from specific interactions with carbon surface chemical groups. The overall behavior can be understood within the experimental and theoretical framework used and I will go on to describe how this approach may be used as a basis to predict adsorption behavior of systems for which no experimental data exist.
In the second part of the presentation I will take surface engineering examples to show how macroscopic behavior can be characterized and influenced at the nanoscale. The use of plasma enhanced CVD methods to modify the adsorptivity of commercial active carbons will be considered in terms of both carbon hydrophobicity and adsorbate size selectivity. Using this deposition approach, it appears possible to produce carbons which are partially hydrophobic and therefore less susceptible to pore blocking and loss of adsorption capacity due to ambient water adsorption in practical use. Constriction of pore entrances due to kinetic ‘gate’ effects is also observed which means that, if suitably control can be achieved, these materials may be of use for gas separations such as hydrogen enrichment. The theme of carbon surface modification will be extended to show the effects of electrolytic surface treatments of carbon fibres on the inter laminar shear strength of carbon fibre reinforced plastic composites and the general relationships between fibre surface chemistry, wettability and composite property will be discussed.
To conclude I will discuss polymer surface engineering more generally and show examples of UV/ozone and plasma methods which lead to changes in surface roughness and adhesion which can be studied using scanning probe microscopy. I will also show how this technique can be used to obtain micromechanical information from surfaces. The use of micropatterning techniques to produce chemically heterogeneous surfaces will be discussed and examples given of how these surfaces can be used in comparative adsorption studies and as templates in new areas of technology such as biomaterials and tissue engineering.