Science and Engineering at the University of Edinburgh
Prof Vasileios Koutsos
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Research: Soft Materials, Complex Fluids, Surfaces & Interfaces

We are interested in the behaviour of soft materials and complex fluids at surfaces & interfaces. Complex fluids consisting of two or more components, such as nanocolloid or polymer suspensions, polymer blends, block copolymers, exhibit unusual physical properties due to the geometric constraints imposed by the coexistence of the different phases. When confined on surfaces, there is an additional geometric constraint which induces further changes in their behaviour. Polymers and nanocolloids can self-assemble into a variety of nanostructures and nanopatterns at interfaces offering alternative ways of facile and inexpensive nanofabrication routes which have great potential for many applications ranging from micro/nanoelectronics to biomedical implants.

There are plenty of unsolved problems in our understanding of the behaviour of complex fluids in confined spaces. The prediction and determination of materials/fluids properties at the nanoscale is not a trivial task and unexpected deviations from bulk behaviour are not uncommon. We study systematically micro/nanostructures formed on surfaces by the self assembly of various complex fluid systems such as diblock copolymers, binary polymer blends, star polymers and nanocolloids. Our experimental work shows the formation of thin films and soft nanostructures which are the direct consequence of confinement and/or interfacial interactions with the solid substrate. The overall behaviour on surfaces is usually different to what is expected from bulk behaviour. The phenomena studied include lamellae formation parallel to the substrate for asymmetric diblock copolymers, 2D jamming of star polymers, increased elastic modulus of polymer nanodroplets due to surface ‘pinning’. The experiments are complemented by scaling theory, continuum theory and computer simulations.

Particular emphasis is laid on using the atomic force microscope (AFM) as an advanced multipurpose tool to probe not only the nanometre-scale morphology but also the nanomechanical/rheological, physicochemical, adhesive and frictional properties of surfaces, ultrathin films, nanostructures and nanomaterials for both fundamental studies and applications (chemical industry, manufacturing, biotechnology & biomedicine, micro/nanoelectronics).

The following links detail the main research themes:

Diblock Copolymers

(a) High contrast AFM topography image highlighting the cone-like terraced structure of a symmetric Poly(isoprene‑b‑ethylene Oxide) (PI-b-PEO) diblock copolymer; also note the dendritic morphology of the first thin monolayer. (b) AFM amplitude image (amplitude scale: 616 mV) of (a). (c) AFM phase image (angle units: degrees) of the area presented in (a). (d) Height profile of the corresponding image; the cone-like structure consists of 5 layers. (e) AFM 3D image of a different cone-like terraced area of symmetric PI-b-PEO block copolymer containing 8 layers (image: 20×20 μm2 and z-scale: 242 nm). (f) Schematic drawing of the first thin monolayer directly over the mica substrate and the lamellae on top of the monolayer.

More details, including the asymmetric PI-b-PEO case, in

  • M. Kalloudis, E. Glynos, S. Pispas, J. Walker, V. Koutsos. Thin Films of Poly(isoprene-b-ethylene oxide) Diblock Copolymers on Mica: An Atomic Force Microscopy Study. Langmuir 2013, 29 (7), 2339 - 2349
  • E. Glynos, S. Pispas, V. Koutsos. Amphiphilic Diblock Copolymers on Mica: Formation of Flat Polymer Nanoislands and Evolution to Protruding Surface Micelles. Macromolecules 2008, 41 (12), 4313 - 4320