Community Research and Development Information Service - CORDIS


COLLDENSE Report Summary

Project ID: 642774
Funded under: H2020-EU.1.3.1.

Periodic Reporting for period 1 - COLLDENSE (Hybrid Colloidal Systems with Designed Response)

Reporting period: 2015-01-01 to 2016-12-31

Summary of the context and overall objectives of the project

Colloids found different applications in almost every part of our lives -- medicine, food, cosmetics -- and it might even seem that these systems are fully understood and “tamed”. In reality, this is far from the case! Both fundamental understanding and a clear application strategy are required. Nowadays, soft and anisotropic colloids are in high demand, not only due to their rich phase behaviour, but also due to the possibility to control them with various external drives. The main aim of COLLDENSE is to elucidate the relationship between "shape/internal structure/deformability of a single colloid"-"density of the hybrid colloidal system"-"external drive (shear, field, pH)" and the “macroscopic response/phase behaviour of these systems”. Scientific part of COLLDENSE is divided into three scientific workpackages (WPs) according to the hierarchical complexity of the building blocks. The main objective of the WP1 is to understand the behaviour of soft colloids, such as star polymers, micelles, droplets both in the equilibrium conditions and under mechanical, electric and rheological drives. WP2 is dedicated to the study of hybrid colloids such as telechelic stars, dipolar colloids and functionalized droplets. Finally, in WP3 we study mixtures of various colloids from the WP1 and WP2. This combination allows to obtain the broad knowledge about mechanical and rheological properties of colloidal systems, being able at the same time, to trace back the dependence on the complexity of building blocks through comparing results obtained in different WPs.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The most challenging and potentially useful deformable colloids are those that can readily change both volume and shape. To this end, we have designed 5 specific projects, within WP1, encompassing synthesis, detailed experimental analysis, simulations and theoretical modelling of the properties deformable colloids under the external drive. Here, experimentally we start with single droplets and using optical microscopy describe their pair interaction. It turned out that the composition of droplets is a key parameter to tune, in order to change their behaviour. To this end, another project studies in computer simulations the mobility of a single 3D droplet depending on its composition and the properties of the solvent. We showed that the transition from the osmosis to the electrophoresis can be found changing the solvation energy of the droplet. The ensemble of droplets is also addressed currently in the simulations of the 3rd project, where the first signs of the soft-hard transition in a 2D system was found (third project). The effects of shear are also studied by the 4th project experimentally. Here, first possible scenarios for jamming were proposed during the reporting period. Finally, to elucidate the mechanical properties and the phase diagram, a new theoretical approach (5th project) has already shown the limitations of pair-wise interactions and the dependence of the variety of structures on the softness of the colloids, using free energy minimization. In WP2, we study hybrid colloids: DNA coated droplets, functionalized micelles, micro gels, telechelic star polymers and dipolar colloids. In the 1st project, using optical tweezers and microscopy, first DNA coated droplets were synthesized, whose interactions can be tuned by light. Continuing along the line of tuneable interactions, it was shown that the rheological behaviour of the functionalized telechelic stars can be controlled by changing their topology. For that, in the 2nd project a special molecular dynamics method was developed. Experimentally, in the 3rd project special micelles and microgels were synthesized with tuneable isotropic attractive interaction. First comparison of the rheology and relaxation of the gels made of these hybrid colloids were studied. In simulations, relaxations of these systems are addressed in the 4th project of WP2. It was shown that shear can change their behaviour from percolation to phase separation. Talking about percolations and phase transitions in hybrid colloids is impossible without having a stable method to calculate cluster partition functions. This method has been developed in the frame-work of the 5th project in WP2 and tested for hybrid dipolar colloids. One of the most versatile and efficient strategies for designing new materials with unconventional behaviour is based on competitive interactions. This is the part of COLLDENSE (WP3), in which we study mixtures of complex colloids. The first project in WP3 is studying the mixture of two population of colloids in order to construct gels with controllable strength. The first results show a large potential of such mixtures for industrial applications. The 2nd industrial project is dedicated to the study of self-filtration and jamming in gels. During the first period it has been shown that the rheology of these systems can be controlled by tuning the process of gel drying under different conditions and confinements. Rheological measurements is also the subject of the 3rd project. Here, however, the mixture of various grafted anisotropic nanoparticles are investigated. First shape-dependent results on the flow of these systems were obtained. The last two projects address the study of DNA gels. The purpose of one of them is to develop a simulation hybrid Monte Carlo method for DNA origami, whereas, in the second one, the experimental synthesis and light/neutron scattering characterization of DNA stars is performed. Both projects show first result on the properties of DNA mixt

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The ESRs have a unique opportunity to perform research in a highly active, interdisciplinary and inter-sectorial environment. As a result, more than 50 scientific papers were published during the reporting period. All of them are now available to broad audience due to the open access policy. More than 40 oral and poster presentations were delivered at more than 10 international scientific events, such as schools, workshops and conferences. Our ESRs are trained in applying and developing state-of-the-art theoretical, numerical, and experimental techniques to tackle problems in the fabrication of new colloidal materials, and have a unique possibility to travel between nodes (more than 50% of the ESRs made at least one secondment in a different COLLDENSE node). Furthermore, their exposure to the non-academic sector allows them to obtain hands-on experience into the interplay between academic and industrial research, scaling-up of research results for real-life applications and the relevance of Intellectual Property Rights. This was assured by an industrial training specially organaised for the ESRs of COLLDENSE. The organisation of science for refuges workshops, public lectures, scientific exhibitions and educative workshops (more than 10 events took place in the reporting period) offers benefits toward the public understanding of science, while at the same time sharpening the skills of the ESR’s in putting forward convincingly the relevance of their research work. All these efforts taken by ESRs and PIs of COLLDENSE, we believe, enhance the position that the EU has in the field of soft matter research.
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