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UoR Home > NanoScience Home > Research > Polymer Nanostructures

Polymer Nanostructures

Power

Supercapacitors are essential for the effective development of electric vehicles. Currently, a number of small scale high performance supercapacitors have become available commercially for use in relatively low power electronic applications, but the challenge remains to scale these up for exploitation in large vehicles. Work at Reading has led to the development of a new low cost approach to the production of nitrogen containing high surface area carbon nano-particles. When these are incorporated in to prototype supercapacitors they exhibit power densities which are in excess of current industry targets.

The Proton Exchange Membrane Fuel Cell is now beginning to approach viability However, the costs associated with fuel cell technology are still an order of magnitude too high for widespread acceptance. The key fuel cell component in this type of power source is the membrane-electrode assembly, comprising a thin film of proton-conducting ionomer laminated on each side to a layer of transition-metal catalyst and thence to a porous gas-diffusion electrode. Current work at Reading is focused on the development of new types of the membrane materials with the aim on reducing costs.

 

Smart materials

We have discovered how nano and micro conducting particles can be dispersed in deformable media to yield materials whose electrical conductivities remarkably increases rather than decreases upon deformation. We are exploring the potential for these novel materials as sensors and for use in smart textiles.

The development of molecular sized wires has been a key target in the field of molecular electronics and current work at Reading is making considerable inroads towards realising this target. The approach taken is to polymerise within a nanostructured template with very well defined porous columns. The approach has considerable flexibility and a range of wires can be prepared.

 

Nanocomposites

There is world-wide interest in the inclusion of nano-particles in synthetic polymers to enhance existing properties and to define new ones. We are exploiting the expertise at Reading in time-resolving x-ray and neutron scattering techniques to develop an understanding of how nano-particles such as clays are mixed and exfoliated within a polymer matrix during flow.

We have discovered how small quantities of a low molar mass compound can be dispersed in polymers including biodegradable systems to provide a self-assembling nanoscale framework which directs the subsequent crystallisation to yield high levels of crystal orientation. This control can have a marked influence on the properties of the final material. We are exploring this new approach in a variety of materials including those used for preparing medical implants and scaffolds.

 

Optical

Photonic crystals provide the analogous properties for light as semi-conductors provide for electrons. Self-assembly is seen as the key in this materials demanding area. We are developing novel polymers for use in self-assembling photonic crystals for exploitation in the visible and infra-red spectral regions.

Security is a vital area in today's society and we have initiated a major programme to develop novel security devices which use nano-structured surfaces to define the optical properties of thin films. These are designed at the outset to have the potential for volume manufacturing to facilitate use in protecting documents, ID cards and high value goods.

 

Molecular Machines

We are working on the development of nanoscale machines in which molecular components assemble into larger structures and modify one another’s behaviour. Our best example of this so far is a molecular tweezer which can grip a second molecule between its arms and induce significant changes in the shape and spectroscopic characteristics of the second molecule.

 

Molecular Pumps and Motors

Polyelectrolyte brushes, where chemically charged polymers are grafted to a substrate in an aqueous environment, exhibit an interesting transition between a collapsed and an extended state induced by changing the pH. This transition offers a convenient mechanism of converting chemical energy into mechanical energy to form various nanoscale machines. See for example www.polymercentre.org.uk/expert/features/0101.php for a possible design of a nanoscale pump. We are currently involved in developing the theory for these new exciting systems.

 

Nanoscale Templating

This is a relatively new method for the production of nanostructured materials and employs surfactant molecules as templating agents. Surfactant templating utilises the 3D aggregate structures (true liquid crystalline phases) formed by surfactant molecules as moulds around which a solid material may subsequently be formed. Electrodeposition of adherent nanostructured films from these templates has been achieved. The surfactant method of nanostructuring has been shown to be useful for the preparation of a wide variety of materials, such as many metals/metal oxides/hydroxides and semiconductors, and ease of fabrication suggest that the use of these materials in the fields of batteries, fuel cells and electrochemical capacitors may be advantageous.

Block copolymers involve the bonding together of two or more incompatible polymer chains, and are renowned for their self-assembly into nanoscale periodic morphologies with wide-ranging symmetries. In recent years, thin layers of block copolymer material have been used as templates for etching patterns into various substrates. One intended application is to etch nanoscale holes into silicon wafers in which ferromagnetic material is deposited to form ultrahigh-density magnetic-storage devices. We are involved in the theoretical modelling of such pattern formation and the prediction of its symmetry in terms of the molecular characteristics of the block copolymer.

As an alternative to block copolymers, we are also investigating the possible benefits of using binary polymeric brushes to form patterned layers. In this case, two types of chemically incompatible polymers are grafted to the substrate, and they self-assemble into patterned morphologies. The mechanism is very similar to that of block copolymers, but the immobility of the chains offers certain advantages.


Catalysis, Sensors and Data Storage
Polymer Nanostructures
Bioscience and Pharmaceuticals
Biomimetic Nanostructures
Page last updated March 23, 2010
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