Soft Matter Physics

"Soft matter" is a convenient term for materials that are easily deformed by thermal fluctuations and external forces. In short, it refers to ‘all things squishy’! Everyday examples include paint, blood, milk, spreads and ice cream. Soft materials share several characteristic features, e.g. that their building blocks are intermediate in size between atoms and grains, and this is crucial to understanding their behaviour. In the Edinburgh Soft Matter Physics group, we use experiments, computer simulations, and theoretical calculations to understand colloidal and granular model systems for phenomena ranging from jamming to bacterial colonies and to rationally design novel soft materials for use in applications ranging from foods to energy materials.

Overview

The experimental research in our group has two directions: ‘Soft Matter’, a sub-discipline of physics concerned with the study of colloidal suspensions, surfactants and polymers, and Active Matter (see also here) the active or life counterparts of soft matter, such as bacterial suspensions and biological polymers. A large number of the materials studied have industrial applications and the group has a dedicated team who undertake industrially linked research.

Soft matter displays many fascinating properties. One example is shown above, where suspensions of Perspex spheres that act as hard particles (~1 micron diameter), self assemble into ‘colloidal crystals’ at high densities. The right-hand-side movie, taken with confocal microscopy, shows the crystal growth process, while the iridescence in the main picture is due to individual colloidal crystallites Bragg-scattering incident white light. Soft matter also shows interesting mechanical behaviour. A well known ‘kitchen’ example is ‘shear thickening’ - a concentrated corn starch solution gets harder to stir the harder it is stirred. Significantly, biology is almost entirely made up of ‘living soft matter’ – globular proteins are colloids, DNA is a stiff polymer, and the lipids forming cell membranes are essentially surfactants.

Soft matter has been studied by chemists, chemical engineers and biologists for many years. It is increasingly clear, however, that these systems show generic properties independent of chemical details. For example, all polymers share certain properties simply because they are long strings of balls performing Brownian motion. This is the central reason why physicists are getting interested. Moreover, studying the generic properties of soft matter can give fresh insights into a broad range of fundamental questions that cut across the whole of condensed matter physics, e.g. concerning the nature of disordered solids.

Many experimental projects (mostly done in our interdisciplinary labs for physicists, physical chemists and biologists) are closely related to projects in theory and simulation in our group.

Research interests

Much of our research is funded by successive EPSRC programme grants, the current one running from December 2011 for 6 years. This flexible funding source gives significant scope for exploration of new topics and the exploitation of unexpected opportunities arising from on-going research, and for postdoctoral researchers to work on multiple projects. The main directions of our research are:

Rheophysics of soft matter

What physical mechanisms govern the yielding and flow of dense colloids, gels and emulsions and how are these related to the ‘dynamical arrest’ or jamming in these systems without flow? We study these problems via confocal microscopy of the flow (particle tracking and velocimetry) with simultaneous rheological measurement. These experiments give important new insights in this field, sometimes overthrowing accepted ideas and results in concentrated colloid rheology. For example, the flow of a concentrated hard sphere suspension in a rectangular channel (flow profile shown in figure) is not like that of a ‘yield stress fluid’, but behaves instead more like dry grains (click here for the paper). For more details on the various projects, see below.

Physics of barriers in soft matter and biology

The ‘aging’ of concentrated metastable states in colloids (‘glasses’), the switching between different phenotypes in bacteria, and the nucleation of growth of fibrillar aggregates in certain proteins (see picture, click here and here for related papers) share a common feature – all three processes involve crossing energy (or free energy) barriers. Experimental work in all three areas will be complemented by novel simulations and analytic theory. We believe generic features will emerge despite apparent dramatic differences between these experimental systems.

New soft materials

An emerging research focus is the study of colloidal particles dispersed in complex solvents, in particular various liquid crystals and phase-separating binary fluids. Often, new soft materials result. Because of the presence of an ‘intermediate length scale’ between colloids and the bulk, the properties of these materials can often be tuned by altering kinetic pathways during their preparation. For example, the picture shows what happens when a binary liquid mixture phase separates under the ‘spinodal’ mechanism in the presence of particles that wets the two phases equally – a bicontinuous jammed emulsion (bijel) is formed (see the paper announcing its discovery and a more recent one on the effect of the particle size). We are also interested in gels formed by fibrillar protein aggregates (see also under barrier crossing). While in vivo these are associated various neurodegenerative diseases, our interest is more in using these as structural elements in building new soft materials.

Physics of cellular motion

The current experimental focus here is on the motility of bacteria (see picture for E. coli cells with their flagella) in complex polymer media – concentrated polymer solutions as well as porous polymer gels (including agar, a standard microbiological culture medium). We are interested in how the polymer affects the motility of single cells, as well as how various kinds of collective motion may emerge, either ‘on its own’, or under the influence of external fields (such as gravity, or gradients in nutrients, etc.). Bacterial motility in confined geometries, such as inside microfluidics devices, is also of interest. This new area emerged partly because we started thinking about bacteria as colloids – they certainly fit into the colloidal domain in terms of size, with their locomotive ability adding extra features. (Click here for a chapter on bacteria as colloids published in the 39th IFF Spring School 2008 at Juelich.)

Physics of bacterial populations

Pseudomonas aeruginosa bacteria colonising an agar surface.
Pseudomonas aeruginosa bacteria colonising an agar surface.
Courtesy of Diarmuid Lloyd.

We are interested in the soft matter and statistical physics of bacterial populations. In particular, we are investigating how bacteria self-assemble to form biofilm communities on surfaces, how they aggregate together in suspension, how they respond to antibiotic treatment and how they interact with each other metabolically in complex and changing environments.

For further information, see Physics of Living Matter.

PhD project opportunities in Soft Matter Physics

People in Soft Matter Physics

Academic staff
Name Position Email address Telephone (UK) Building Room number
Rosalind Allen Lecturer rosalind [dot] allen [at] ed [dot] ac [dot] uk 0131 651 7197 JCMB 2507
Paul Clegg Reader paul [dot] clegg [at] ed [dot] ac [dot] uk 0131 650 5295 JCMB 2614
Oliver Henrich Advanced Fellow EPCC ohenrich [at] epcc [dot] ed [dot] ac [dot] uk 0131 650 5818 JCMB 2405
Cait MacPhee Professor cait [dot] macphee [at] ed [dot] ac [dot] uk 0131 650 5291 JCMB 2613
Davide Marenduzzo Personal Chair in Computational Biophysics dmarendu [at] ph [dot] ed [dot] ac [dot] uk 0131 650 5289 JCMB 2506
Alexander Morozov Reader alexander [dot] morozov [at] ed [dot] ac [dot] uk 0131 650 5882 JCMB 2616
Wilson Poon Professor w [dot] poon [at] ed [dot] ac [dot] uk 0131 650 5297 JCMB 2620
Job Thijssen Chancellor's Fellow j [dot] h [dot] j [dot] thijssen [at] ed [dot] ac [dot] uk 0131 650 5274 JCMB 2421
Simon Titmuss Lecturer simon [dot] titmuss [at] ed [dot] ac [dot] uk 0131 650 5267 JCMB 2504
Research staff
Name Position Email address Telephone (UK) Building Room number
Elena Blanco PDRA m [dot] blanco [at] ed [dot] ac [dot] uk 0131 651 3456 JCMB 1508
Matthew Blow PDRA mblow [at] staffmail [dot] ed [dot] ac [dot] uk 0131 650 5175 JCMB 1506
Keith Bromley Postdoctoral Research Fellow keith [dot] bromley [at] ed [dot] ac [dot] uk 0131 650 6799 JCMB 1601
Aidan Brown PDRA abrown20 [at] staffmail [dot] ed [dot] ac [dot] uk 0131 651 3456 JCMB 2610
Dongyu Cai Research Fellow dongyu [dot] cai [at] ed [dot] ac [dot] uk 0131 650 5229 JCMB 2610
Joost de Graaf Marie Curie Fellow j [dot] degraaf [at] ed [dot] ac [dot] uk 0131 650 5121 JCMB 2601
Clemence Devailly PDRA clemence [dot] devailly [at] ed [dot] ac [dot] uk 0131 651 3456 JCMB 1508
David French PDRA david [dot] french [at] ed [dot] ac [dot] uk 0131 651 3455 JCMB 1509
Steven Gardner Postdoctoral Research Associate steven [dot] gardner [at] ed [dot] ac [dot] uk 0131 651 7771 JCMB 1603
Michiel Hermes PDRA m [dot] hermes [at] ed [dot] ac [dot] uk 0131 650 5883 JCMB 2621
Michal Kepa PDRA mkepa [at] staffmail [dot] ed [dot] ac [dot] uk 0131 651 7222 JCMB 3.3812
Nick Koumakis PDRA nick [dot] koumakis [at] ed [dot] ac [dot] uk 0131 650 5883 JCMB 2621
Thomas Le Goff Postdoctoral Research Associate thomas [dot] le-goff [at] ed [dot] ac [dot] uk 0131 651 3455 JCMB 1509
Benno Liebchen PDRA benno [dot] liebchen [at] ed [dot] ac [dot] uk 0131 650 5175 JCMB 1506
Alex Lips Honorary Professor alex [dot] lips [at] ed [dot] ac [dot] uk JCMB
Diarmuid Lloyd PDRA diarmuid [dot] lloyd [at] ed [dot] ac [dot] uk 0131 651 7742 JCMB 1505
Vincent Martinez PDRA vincent [dot] martinez [at] ed [dot] ac [dot] uk 0131 650 8617 JCMB 2609
Andrew Matheson Postdoctoral Research Associate andrew [dot] matheson [at] ed [dot] ac [dot] uk 0131 650 5263 JCMB 2603
Gavin Melaugh PDRA gmelaugh [at] ed [dot] ac [dot] uk 0131 651 3456 JCMB 1508
Davide Michieletto PDRA davide [dot] michieletto [at] ed [dot] ac [dot] uk 0131 651 7742 JCMB 1505
Javier Otero Marquez Early Stage Researcher javier [dot] otero [at] ed [dot] ac [dot] uk 0131 651 3455 JCMB 1509
Anne Pawsey Industry Research Liaison a [dot] pawsey [at] ed [dot] ac [dot] uk 0131 651 7772 JCMB 1601
Andrew Schofield PDRA a [dot] b [dot] schofield [at] ed [dot] ac [dot] uk 0131 650 7257 JCMB 2203
Marieke Schor PDRA mschor [at] ed [dot] ac [dot] uk 0131 650 7165 JCMB 2617
Jana Schwarz-Linek PDRA jslinek [at] staffmail [dot] ed [dot] ac [dot] uk 0131 650 8617 JCMB 2609
Joe Tavacoli Industrial Research Liaison Officer jtavaco2 [at] staffmail [dot] ed [dot] ac [dot] uk 0131 651 7687 JCMB 2611
Adriano Tiribocchi PDRA atiriboc [at] staffmail [dot] ed [dot] ac [dot] uk 0131 65- 5175 JCMB 1506
Teun Vissers Marie Curie Fellow t [dot] vissers [at] ed [dot] ac [dot] uk 0131 650 5883 JCMB 2621
Justin Whitehouse Postdoctoral Research Assistant j [dot] whitehouse [at] ed [dot] ac [dot] uk 0131 651 7686 JCMB 2509
Tiffany Wood Industrial Research Liaison tiffany [dot] wood [at] ed [dot] ac [dot] uk 0131 651 7687 JCMB 2611
Other staff
Name Position Email address Telephone (UK) Building Room number
Siobhan Liddle Tutor s [dot] liddle [at] ed [dot] ac [dot] uk 0131 650 6799 JCMB 2510
Hugh Vass Technical Staff h [dot] vass [at] ed [dot] ac [dot] uk 0131 650 8616 JCMB 2310
Research postgraduates
Name Email address Telephone (UK) Building Room number
Veronika Afonina s1374087 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 7210 JCMB 2805
Giovanni Brandani s1246659 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 6799 JCMB 2510
Timothy Bush s1118784 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 6799 JCMB 2509
Flaviu Cipcigan s0790438 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 7773 JCMB 1605
Giulio De Magistris s1356442 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 8603 JCMB 2501
Katy Dickinson s0914066 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 7176 JCMB 1511
Ana Fialho s1460631 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 7176 JCMB 1511
Milana Filatenkova s1145105 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 6799 JCMB 2510
Martina Foglino mfoglino [at] staffmail [dot] ed [dot] ac [dot] uk JCMB 1510
Joe Forth s1115855 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 3455 JCMB 1509
Mark Fox-Powell m [dot] fox-powell [at] ed [dot] ac [dot] uk 0131 651 7774 JCMB 1607
Jay Gillam j [dot] e [dot] gillam [at] sms [dot] ed [dot] ac [dot] uk JCMB 2603
Ben Guy s0804561 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 6799 JCMB 2510
Daniel Hodgson s0784104 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 6799 JCMB 2510
Tom Ives s0935333 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 8603 JCMB 2501
James Johnson s0841882 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 8603 JCMB 2501
Nico Kronberg nico [dot] kronberg [at] ed [dot] ac [dot] uk JCMB 4401
Hanna Landenmark s1046113 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 7176 JCMB 1511
Tao Li s1165179 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 6799 JCMB 2510
Benjamin Little s0675186 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 5263 JCMB 2603
Christian Loach s1355587 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 5258 JCMB 3311
Iva Manasi s1374036 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 7176 JCMB 2510
Elliot Marsden elliot [dot] marsden [at] ed [dot] ac [dot] uk 0131 651 3455 JCMB 1509
Laura McKinley l [dot] e [dot] mckinley [at] ed [dot] ac [dot] uk 0131 650 6799 JCMB 2510
Alexander McVey a [dot] f [dot] mcvey [at] ed [dot] ac [dot] uk 0131 651 3454 G.25
Rudi Mears s1563187 [at] sms [dot] ed [dot] ac [dot] uk 07981811595 JCMB 2618
Ryan Morris ryan [dot] morris [at] ed [dot] ac [dot] uk 0131 650 6799 JCMB 1601
Jakub Pastuszak s0789788 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 6799 JCMB 1510
Chay Paterson s1338295 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 8603 JCMB 2501
Samuel Payler s1251564 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 7774 JCMB 1607
Carolina Pereira s1460633 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 7176 JCMB 1511
Ciprian Pruteanu s1028231 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 5258 JCMB 3311
Matthew Reeves s0784777 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 6799 JCMB 2510
Marion Roullet marion [dot] roullet [at] ed [dot] ac [dot] uk 07871203178 JCMB 1506
Katherine Rumble s1345985 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 6799 JCMB 2510
Toby Samuels s1360327 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 7774 JCMB 1607
Laura Sawiak s1478680 [at] sms [dot] ed [dot] ac [dot] uk JCMB 2601
Alexander Slowman s1271420 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 8603 JCMB 2501
Daniel Taylor daniel [dot] taylor [at] ed [dot] ac [dot] uk JCMB 2510
Pat Teeratchanan s1270872 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 6799 JCMB 3311
Stuart Thomson s0828679 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 7176 JCMB 2510
Robin Turnbull s0907517 [at] sms [dot] ed [dot] ac [dot] uk 0131 650 5258 JCMB 3311
Simon Weir s0563200 [at] sms [dot] ed [dot] ac [dot] uk JCMB 2603
Joshua Williams s1461461 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 7176 JCMB 2510
Anthony Wood s1538277 [at] sms [dot] ed [dot] ac [dot] uk JCMB 2618
Xuemao Zhou s1461318 [at] sms [dot] ed [dot] ac [dot] uk 0131 651 7176 JCMB 2510
Last updated: 08 Jan 2016 at 10:52