Recent Highlights

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December 2015

We used the ESRF’s X-rays to study the blue and white feathers of the Jay and have found that birds use well-controlled changes to the nanostructure of their feathers to create the vivid colours of their plumage. This research opens new possibilities into creating non-fading, synthetic colours for paints and clothing. This is published in the open access journal Nature Scientific Reports

October 2015

• Work looking at the way in which Amyloid diseases like Alzheimers damage the cell has been published as an open access article in the journal Soft Matter available here


September 2015

• Heating and cooling cycles like that would be experienced under actual operation are able to make breath pattern structures on the surface of polymer solar cell blend films. This has now been published in the journal Polymer Physics as part of the Ed Kramer special issue polymer physics, also open access.




Blends of block copolymers as anti-counterfeit materials

Coloured materials were made using block copoylmers (an alloy of two different polymers). By mixing the block copolymers together, we were able to create any colour in the rainbow from two non-coloured solutions. This type of polymer then automatically organises itself into a layered structure, causing optical effects similar to opals. The colour also changes depending on the viewing angle see video. This system has huge advantage in terms of cost, processing and colour selection compared to existing systems. The image to the left shows the range of colours that can be made by mixing the two block copolymers in varying proportions. The work was published in Soft Matter 2011, 7, 3721-3725 . We carried out the small angle x-ray measurements Diamond light source This work has been covered extensively in the media Independent online, the BBC, the Engineer and ScienceDaily

fish

Watching phase separation in spin coated polymer blends

Spin coating polymer blend thin films provides a method to produce multiphase functional layers of high uniformity covering large surface areas. This work recently published in ACS Nano has employed synchronized stroboscopic illumination to optically observe structure evolution in such blends during spin coating in real time. The aim was to understand the evolution as the rapidly spinning layer dries to then be able to reliably control the final morphology.The work gave insights to the very early stage evolution of thin film phase separation.

link to the article

video of in-situ spin coating

spin

Layering / stratification in polymer solar cell blends

Using neutron reflectivity, self-stratification in a model P3HT/PCBM blend was observed. The as-spun and solvent-annealed films show a depletion of PCBM near the top surface and enrichment of PCBM at the substrate (see figure). Depletion of PCBM at the cathode interface in a photovoltaic device could act as a barrier to efficient electron extraction. On thermal annealing, the PCBM depleted region is eliminated; an effect that partially explains the improvement of P3HT/PCBM devices on thermal annealing.


Depletion of PCBM at the Cathode Interface in P3HT/PCBM Thin Films as Quantified via Neutron Reflectivity Measurements Andrew J. Parnell, Alan D. F. Dunbar, Andrew J. Pearson, Paul A. Staniec, Andrew J. C. Dennison, Hiroshi Hamamatsu, Maximilian W. A. Skoda, David G. Lidzey, Richard. A. L. Jones Advanced Materials Volume 22, Issue 22, pages 2444–2447, June 11, 2010

link to the article

The development of nanoscale morphology in polymer: fullerene photovoltaic blends during solvent casting

The development of structure and order in a model polymer solar cell blend has been studied using in situ ellipsometry and grazing incidence x-rays. This `dynamic´ information permits a number of basic mechanisms in film-formation processes to be resolved; information that will help the design of new and improved materials for plastic solar cell applications.

Sheffield press release

The development of nanoscale morphology in polymer:fullerene photovoltaic blends during solvent casting Journal Paper, Tao Wang,Alan Dunbar,Paul Staniec,Andrew Pearson,Paul Hopkinson,Emyr Macdonald,Samuele Lilliu,Claire Pizzey,Nicholas Terrill,Athene Donald,Anthony Ryan,Richard Jones,David Lidzey, Soft Matter link to the article

Self-Motile Colloidal Particles

Directing objects on the small scale is an intriguing problem that has been studied recently by researchers from our group. Jon Howse (who has recently been appointed a lecturer in chemical engineering at Sheffield) examined the motion of an artificial microscale swimmer that uses a chemical reaction catalyzed on its own surface, in order to achieve autonomous propulsion. This catalyst is distributed asymmetrically on the surface and propels the particle by a process called self diffusiophoresis. At short time scales directed propulsion was observed whilst at longer times the motion of the particles becomes more diffusive in behavior.

Howse et al, Physical Review letters 99, 048102 (2007) (Subscription required)