"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 subdiscipline 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 righthandside movie, taken with confocal microscopy, shows the crystal growth process, while the iridescence in the main picture is due to individual colloidal crystallites Braggscattering 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 ongoing 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 phaseseparating 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 39^{th} IFF Spring School 2008 at Juelich.)
Physics of bacterial populations
We are interested in the soft matter and statistical physics of bacterial populations. In particular, we are investigating how bacteria selfassemble 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
 Bringing Order to a ‘Zoo’ of Colloidal Gels
 Combining neutron reflectivity experiments with coarsegrained molecular dynamic simulations: a synergistic approach to determining the structure and dynamics of bacterial membranes
 Fabrication Routes for Soft Energy Materials Aligned with Industrial Processes
 How Do Colloidal Particles Flow at Liquid Interfaces?
 How do Dense Suspensions Flow?
 Proteins as interfacial stabilisers  improving lowfat foods and increasing satiety
 Soft materials for the Liair battery electrode
 The physics of active colloids
 The Salvinia Effect on a colloidal scale
 Theory and Simulation of Microbial Swimmers and Subcellular Liquid Crystals
 Using dipeptide fibres to stabilize a foam
 Using spin echo reflection grazing incidence scattering and spectroscopy (SERGIS/GINSES) to probe the mechanical properties of interfacial thin films
People in Soft Matter Physics
Name  Position  Contact details  Location  Photo 

Rosalind Allen  Lecturer 
rosalind [dot] allen [at] ed [dot] ac [dot] uk 
JCMB 2507 

Aidan Brown  Chancellor's Fellow 
abrown20 [at] staffmail [dot] ed [dot] ac [dot] uk 
JCMB 2610 

Paul Clegg  Reader 
paul [dot] clegg [at] ed [dot] ac [dot] uk 
JCMB 2614 

Oliver Henrich  Advanced Fellow EPCC 
ohenrich [at] epcc [dot] ed [dot] ac [dot] uk 
JCMB 2405 

Cait MacPhee  Professor 
cait [dot] macphee [at] ed [dot] ac [dot] uk 
JCMB 2613 

Davide Marenduzzo  Personal Chair in Computational Biophysics 
dmarendu [at] ph [dot] ed [dot] ac [dot] uk 
JCMB 2506 

Alexander Morozov  Reader 
alexander [dot] morozov [at] ed [dot] ac [dot] uk 
JCMB 2616 

Wilson Poon  Professor 
w [dot] poon [at] ed [dot] ac [dot] uk 
JCMB 2620 

Job Thijssen  Chancellor's Fellow 
j [dot] h [dot] j [dot] thijssen [at] ed [dot] ac [dot] uk 
JCMB 2421 

Simon Titmuss  Lecturer 
simon [dot] titmuss [at] ed [dot] ac [dot] uk 
JCMB 2504 
Name  Position  Contact details  Location  Photo 

Jochen Arlt  Research Fellow 
j [dot] arlt [at] ed [dot] ac [dot] uk 
JCMB 2601 

Elena Blanco  PDRA 
m [dot] blanco [at] ed [dot] ac [dot] uk 
JCMB 1508 

Matthew Blow  PDRA 
mblow [at] staffmail [dot] ed [dot] ac [dot] uk 
JCMB 1506 

Keith Bromley  Postdoctoral Research Fellow 
keith [dot] bromley [at] ed [dot] ac [dot] uk 
JCMB 1601 

Timothy Bush  PDRA 
t [dot] bush [at] ed [dot] ac [dot] uk 
JCMB 2509 

Dongyu Cai  Research Fellow 
dongyu [dot] cai [at] ed [dot] ac [dot] uk 
JCMB 2610 

Niccolo De Francesco  Research Assistant 
nicco [dot] defran [at] ed [dot] ac [dot] uk 
JCMB 2612 

Joost de Graaf  Marie Curie Fellow 
j [dot] degraaf [at] ed [dot] ac [dot] uk 
JCMB 2601 

Clemence Devailly  PDRA 
clemence [dot] devailly [at] ed [dot] ac [dot] uk 
JCMB 1508 

David French  PDRA 
david [dot] french [at] ed [dot] ac [dot] uk 
JCMB 1509 

Steven Gardner  Postdoctoral Research Associate 
steven [dot] gardner [at] ed [dot] ac [dot] uk 
JCMB 1603 

Martin Gorman  PDRA 
m [dot] gorman [at] ed [dot] ac [dot] uk 
CSEC 2.2805 

Daniel Hodgson  PDRA 
daniel [dot] hodgson [at] ed [dot] ac [dot] uk 
JCMB 2603 

Michal Kepa  PDRA 
mkepa [at] staffmail [dot] ed [dot] ac [dot] uk 
JCMB 3.3812 

Nick Koumakis  PDRA 
nick [dot] koumakis [at] ed [dot] ac [dot] uk 
JCMB 2621 

Thomas Le Goff  Postdoctoral Research Associate 
thomas [dot] legoff [at] ed [dot] ac [dot] uk 
JCMB 1509 

Benno Liebchen  Marie Curie Fellow 
benno [dot] liebchen [at] ed [dot] ac [dot] uk 
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 
JCMB 1505 

Vincent Martinez  PDRA 
vincent [dot] martinez [at] ed [dot] ac [dot] uk 
JCMB 2609 

Andrew Matheson  Postdoctoral Research Associate 
andrew [dot] matheson [at] ed [dot] ac [dot] uk 
JCMB 2603 

Gavin Melaugh  PDRA 
gmelaugh [at] ed [dot] ac [dot] uk 
JCMB 1508 

Davide Michieletto  PDRA 
davide [dot] michieletto [at] ed [dot] ac [dot] uk 
JCMB 1505 

Rory O'Neill  PDRA 
rory [dot] o'neill [at] ed [dot] ac [dot] uk 
JCMB 1510 

Javier Otero Marquez  Early Stage Researcher 
javier [dot] otero [at] ed [dot] ac [dot] uk 
JCMB 1509 

Anne Pawsey  Impact Acceleration Associate 
a [dot] pawsey [at] ed [dot] ac [dot] uk 
JCMB 1601 

Andrew Schofield  PDRA 
a [dot] b [dot] schofield [at] ed [dot] ac [dot] uk 
JCMB 2203 

Marieke Schor  PDRA 
mschor [at] ed [dot] ac [dot] uk 
JCMB 2617 

Jana SchwarzLinek  PDRA 
jslinek [at] staffmail [dot] ed [dot] ac [dot] uk 
JCMB 2609 

Teun Vissers  Marie Curie Fellow 
t [dot] vissers [at] ed [dot] ac [dot] uk 
JCMB 2621 

Tiffany Wood  Director of the Edinburgh Complex Fluids Partnership 
tiffany [dot] wood [at] ed [dot] ac [dot] uk 
JCMB 2611 
Name  Position  Contact details  Location  Photo 

Siobhan Liddle  Tutor 
s [dot] liddle [at] ed [dot] ac [dot] uk 
JCMB 2510 

Hugh Vass  Technical Staff 
h [dot] vass [at] ed [dot] ac [dot] uk 
JCMB 2310 
Name  Position  Contact details  Location  Photo 

Veronika Afonina  Postgraduate Student 
s1374087 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2805 

Giovanni Brandani  Postgraduate Student 
s1246659 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 

Flaviu Cipcigan  Postgraduate Student 
s0790438 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 1605 

Giulio De Magistris  Postgraduate Student 
s1356442 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2501 

Katy Dickinson  Postgraduate Student 
s0914066 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 1511 

Ana Fialho  Postgraduate Student 
s1460631 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 1511 

Milana Filatenkova  Postgraduate Student 
s1145105 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 

Martina Foglino  Early Stage Researcher 
mfoglino [at] staffmail [dot] ed [dot] ac [dot] uk 
JCMB 1510 

Mark FoxPowell  Postgraduate Student 
m [dot] foxpowell [at] ed [dot] ac [dot] uk 
JCMB 1607 

Joe French  Postgraduate Student 
joseph [dot] french [at] ed [dot] ac [dot] uk 
JCMB 2603 

Jay Gillam  Postgraduate Student 
j [dot] e [dot] gillam [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2603 

Emily Gould  Postgraduate Student 
e [dot] m [dot] gould [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 1616 

Samuel Griffiths  Postgraduate Student 
s [dot] e [dot] griffiths2 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 

Ben Guy  Postgraduate Student 
s0804561 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 

Tom Ives  Postgraduate Student 
s0935333 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2501 

James Johnson  Postgraduate Student 
s0841882 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2501 

Navneeta Katyan  Postgraduate Student 
n [dot] katyan [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 

Nico Kronberg  Postgraduate Student 
nico [dot] kronberg [at] ed [dot] ac [dot] uk 
JCMB 4401 

Hanna Landenmark  Postgraduate Student 
s1046113 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 1511 

Tao Li  Postgraduate Student 
s1165179 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 

Benjamin Little  Postgraduate Student 
s0675186 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2603 

Christian Loach  Postgraduate Student 
s1355587 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 3311 

Iva Manasi  Postgraduate Student 
s1374036 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 

Elliot Marsden  Postgraduate Student 
elliot [dot] marsden [at] ed [dot] ac [dot] uk 
JCMB 1509 

Laura McKinley  Postgraduate Student 
l [dot] e [dot] mckinley [at] ed [dot] ac [dot] uk 
JCMB 2510 

Alexander McVey  Postgraduate Student 
a [dot] f [dot] mcvey [at] ed [dot] ac [dot] uk 
G.25 

Rudi Mears  Postgraduate Student 
s1563187 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2618 

Ryan Morris  Postgraduate Student 
ryan [dot] morris [at] ed [dot] ac [dot] uk 
JCMB 1601 

Francois Mouvet  Visitor 
francois [dot] mouvet [at] epfl [dot] ch 
JCMB 1510 

Ed Muir  Postgraduate Student 
s1620953 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 

Iain Muntz  Postgraduate Student 
s1123068 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 1616 

Jakub Pastuszak  Postgraduate Student 
s0789788 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 1510 

Chay Paterson  Postgraduate Student 
s1338295 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2501 

Samuel Payler  Postgraduate Student 
s1251564 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 1607 

Carolina Pereira  Postgraduate Student 
s1460633 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 1511 

Ciprian Pruteanu  Postgraduate Student 
s1028231 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 3311 

Matthew Reeves  Postgraduate Student 
s0784777 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 

James Richards  Postgraduate Student 
j [dot] a [dot] richards3 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2603 

Marion Roullet  Postgraduate Student 
marion [dot] roullet [at] ed [dot] ac [dot] uk 
JCMB 1506 

Katherine Rumble  Postgraduate Student 
s1345985 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 

Toby Samuels  Postgraduate Student 
s1360327 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 1607 

Laura Sawiak  Postgraduate Student 
s1478680 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2601 

Alexander Slowman  Postgraduate Student 
s1271420 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2501 

Daniel Taylor  Postgraduate Student 
daniel [dot] taylor [at] ed [dot] ac [dot] uk 
JCMB 2510 

Pat Teeratchanan  Postgraduate Student 
s1270872 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 3311 

Stuart Thomson  Postgraduate Student 
s0828679 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 

Robin Turnbull  Postgraduate Student 
s0907517 [at] sms [dot] ed [dot] ac [dot] uk 
CSEC 2.2804 

Simon Weir  Postgraduate Student 
s0563200 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2611 

Joshua Williams  Postgraduate Student 
s1461461 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 

Anthony Wood  Postgraduate Student 
s1538277 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2618 

Xuemao Zhou  Postgraduate Student 
s1461318 [at] sms [dot] ed [dot] ac [dot] uk 
JCMB 2510 