CoPEC · Colloidal particles in elasto-capillary fields

Colloidal particles in elasto-capillary fields

The “CoPEC” project was a fundamental research project designed to advance knowledge in the field of soft matter Physics, and more particularly in the area of colloids and complex fluids interfaces. The main task of the proposal was to investigate the physical properties of colloidal particles evolving in elastocapillary fields, which can be realized by considering, e.g., particles attached to liquid crystal (LC) fluid interfaces. Such systems remain largely unexplored today and represent a new type of material whose properties are anticipated to be mainly governed by the coupling between capillary and elastic phenomena. The former originates from the surface tension inherent to any fluid interface, whereas the latter is intrinsic to all liquid crystal phases. These phenomena have always been considered separately in previous works, and consequently, examining their intimate coupling has been one of the salient and innovative aspects of the “CoPEC” project. Indeed, elasto-capillary couplings may lead to novel colloidal interactions and the subsequent discovery of new collective properties which could be exploited to design materials with yet unknown important functions. Potential areas of impact include optical applications such as the next generation of ‘smart’ PDLC (Polymer Dispersed Liquid Crystals) windows or drug delivery systems at the micro- or sub-micrometer scale for the pharmaceutical industry. The project was carried out using numerical simulations based on continuum theories. The overall objective was to develop computer models to gain basic knowledge on the behavior of colloidal particles adsorbed at liquid crystal interfaces. Understanding collective phenomena, which are essential to make predictions on potentially interesting applications, was one of the final scientific targets of the project. But prior to addressing multi-particle systems, a large part of the project first focused on gaining general knowledge on (i) the behavior of a single particle, and (ii) pair interaction potentials. Overall, “CoPEC” fulfilled its main objective, i.e. new computer codes could be designed and developed to improve our understanding of particles straddling LC interfaces. Unexpected results (see below), essentially at the single particle level, were unveiled due to the aforementioned elastocapillary coupling, allowing new insights to be gained. However, a great deal of efforts are still needed to fully characterize such systems, whose physical properties are very rich due to the numerous intertwined effects (e.g., capillarity, elasticity, multiphase flows).

Data: CORDIS, © European Union