Research activity

Studying lipid membranes is essential to understand their behaviour, design novel drugs, and target specific functions. At the PSCM, substantial efforts are deployed to increase our understanding of lipid membranes through well-characterized membrane models for physical and biological studies. Research activity covers: (i) extraction and purification of deuterated natural lipids from yeast and bacteria, to better mimic the complexity of living systems, (ii) investigations of structure and dynamics in lipid mono- and bi-layers to gain fundamental insight into their behavior, and (iii) studying the interactions of lipid membranes with colloidal objects, such as proteins, polymeric micelles, or nanoparticles. We support for example scientists investigating the structure of lipid films at the water surface and on solid supports. We also collaborate on the development and test of experimental apparatuses able to measure additional membrane properties - such as electrostatic charging - during scattering and diffraction experiments.

Controlling the spontaneous assembly of colloidal objects into supramolecular particles is one of the main research lines at the PSCM. In particular, we study the self-assembly of surfactant molecules, the formation of inclusion complexes with cyclodextrins, and their interaction with polymers in aqueous solution and at interfaces. In this context, natural polyelectrolytes play a primary role. Furthermore, we tune the spontaneous assembly of polyelectrolytes by employing stimuli-responsive counterions and we investigate the surfactant-induced self-assembly of nanoparticles at liquid-liquid interfaces. Additional examples include time and temperature resolved studies of interfacial molecular freezing, volume transitions in spherical polyelectrolyte brushes, and growth of worm-like vesicles in solution.

In addition to offering access to a wide range of conventional laboratory tools for the preparation and characterization of soft matter samples, the PSCM contributes also to the in-house development of specific setups and technologies aimed at a more efficient use of the ILL and ESRF large-scale instruments allowing the users to perform experiments under complex conditions. For example, we are implementing a 3D-printing facility used to produce e.g. sample holders, compact experimental cells, and advanced microfluidic systems of interest for soft matter, materials, and life sciences. We are also specializing in the development of cryogenic and nano-scanning sample environment for the biophysical investigations of cells and soft tissues. We also optimize atomic force microscopy nano-mechanical operation modes with applications in e.g. thin films and wood science. Finally, equipment is under development to study a broad variety of systems under controlled humidity conditions, high hydrostatic pressure or shear load. The in-situ combination of laboratory methods with the large scale instruments is also developed, e.g. light or X-ray scattering, infrared spectroscopy, ellipsometry, QCM-D and rheology.

The PSCM contributes also to research endeavours that address materials ranging from colloids to complex systems, and involving both fundamental scientific interest and widespread applications with societal impact. For example, we (a) synthesize model colloids and characterize their structural and dynamical features across phase transitions, (b) investigate in-situ the nucleation, growth and aggregation of nanoparticles in solution, (c) characterize the bulk and interface nanostructure of ionic liquids and complex fluids, (d) investigate the structure and dynamics of microemulsions and ouzo-systems, (e) characterize chemical reactions and ionic effects in molecular systems at air-liquid, liquid-liquid and solid-liquid interfaces. We also support researchers investigating complex biological materials ranging from silk, pollens, nacre and sea-shells to cells, tissues, muscles and bones.

Last two decades brought a spectacular increase of scientific research devoted to synthetic and living systems that extract energy from their environment at the single particle level and convert to mechanical work in the form of self-propulsion. These systems are out-of-equilibrium and manifest a variety of collective phenomena as the control parameters are tuned. Examples of active matter include systems as diverse as flocks of birds, motile microorganisms, molecular motors and synthetic Janus particles in an active medium. The emergent dynamics of these systems at the particulate level (superdiffusion, mean propulsion speed, velocity fluctuations, etc.) can be probed  using X-ray scattering methods (USAXS, XPCS, etc.). Current inhouse activities involve phoretic dynamics induced by solvent phase separation, self-phoretic dynamics of Janus colloids in catalytic media, etc. The scattering methods derive ensemble averaged static and dynamic information in the thermodynamic limit. The PSCM provides support to users for the investigation of model systems using different scattering methods, following the approval by the peer review.

Given the importance of polymers in our worlds, it is appropriate to define our time as the Age of Polymers, in analogy to the Stone, Bronze, and Iron Age. At the PSCM, polymers play a very important role, and we investigate the behaviour of polymer blends, polymer solutions, polymer coatings, microgels, and mixtures of polymers with other colloids such as surfactants and nanoparticles. In particular, the response of polymer-based systems towards external stimuli such as temperature, pressure, or pH, is explored. In addition, we investigate for example the spontaneous organization of copolymers into complex nanostructures, explore the effect of polymers on physico-chemical phenomena such as biomineralization and nanoparticle growth, and optimize polymer-based inks for 3D-printing. We also support the micro/nano-structural investigation of biopolymers such as starch and cellulose, and of high performance materials such as Peek and Kevlar micro-fibers.