Brack - Surface modification and characterisation of advanced materials
Our research focuses on creating, understanding and controlling materials at the nanometer scale. We have a strong focus on surface science, in particular, exploring chemical and molecular properties and processes at surfaces and at interfaces. Surface modification strategies have been designed and developed for a diverse range of material systems including next generation aircraft materials, carbon nanomaterials and electrospun nanofibres. Surface analytical studies have provided significant insight into the fundamental aspects and properties of these systems.
We have made significant and innovative contributions in a number of research fields, for example:
- growth and manipulation of CNTs for improved strength composite materials
- ultrasonicated ozone modification of exfoliated graphite and CNTs for ink jet printing applications and hierarchical-nanocomposite materials
- next generation aerospace materials
- micropatterning of fluoropolymer surfaces.
Production, properties and potential of iron-carbon nanomaterials
Ferromagnetic carbon nanomaterials offer significant interest for many applications such as high-capacity hydrogen storage, drug delivery, electron transfer applications and electromagnetic shielding. We use carbon nanomaterials, such as carbon nanotubes, graphene nanoplatelets and iron, as building blocks to create multifunctional nanomaterials; thereby extending their application from simple to complex functions. Simple, economically viable and scalable processes are employed to create these materials, offering new and exciting opportunities in the area of magnetic field sensors.
The relationship between nanoscale chemistry and structure of these materials and their magnetic properties provides invaluable insight into their enhanced functionality compared to conventional bulk materials. By incorporating these materials into industrially relevant platforms, we create smart composites for magnetic field sensors.
Chemical and electronic modification of carbon nanomaterials using nitrogen plasma
Nitrogen doped carbon nanomaterials offer significant potential as catalysts for fuel cell applications especially at the oxygen reduction cathode. They offer a metal free and inexpensive alternative to precious metal catalysts (Pt) without sacrificing catalytic activity.
The incorporation of nitrogen atoms into carbon nanotubes or graphene has been achieved by introducing the dopant species to the feedstock during chemical vapour deposition or by post annealing in a nitrogen containing atmosphere. These approaches fail to provide a homogenous distribution, to control the nature of the dopant species and site selectivity. An alternative versatile approach is plasma treatment which offers short treatment times, high doping yields and control over introduced nitrogen functionalities. We explore the effect of nitrogen plasma treatments on carbon nanotubes and graphene nanoplatelets in terms of changes to the surface chemistry, electronic properties and oxygen reduction activity.
Surface grafting of electrospun fibres for the control of biointerfacial interactions
The development of electrospun nanofibres from biodegradable and biocompatible polymers has created exciting opportunities for biomedical applications. Meshes of fibres with high surface areas, porosities and appropriate stiffness have been produced through the electrospinning technique.
Despite their desirable structural and topographical properties, the nature of the fibre surface has inhibited their development. Hydrophobicity, undesirable non-specific protein adsorption and bacterial attachment and growth, coupled with a lack of surface functionality and a full understanding of the interactions between cells and extracellular matrix (ECM) molecules have impeded the success of these systems.
Chemical and physical treatments have been applied to the fibres in order to modify or control their surface properties. Chemical modification using controlled living radical polymerization has successfully introduced advanced functionalities on the surface of some fibre systems. Atom transfer radical polymerization (ATRP) and reversible addition fragmentation chain transfer (RAFT) techniques are two of the most widely investigated techniques.
We explore the surface of electrospun nanofibres scaffolds via controlled living radical polymerization in order to create low fouling materials for cardiovascular applications. The surface modification of the fibres is expected to reduce the foreign body response improving biointerfacial interactions. In vitro and in vivo assays is undertaken to analyse cell and material interactions and corroborate the low fouling properties of the fibres.