DELTAS · The dynamics and rheology of self-assembled empty liquids: from patchy toy models to anisotropic realistic systems

The dynamics and rheology of self-assembled empty liquids: from patchy toy models to anisotropic realistic systems

The fabrication of versatile building blocks that reliably self-assemble into desired ordered and disordered phases is amongst the hottest topics in contemporary materials science. The possibility of fine-tuning the structure of these materials by changing the microscopic details of the building blocks lend themselves well to many applications, ranging from medicine to material science. The problem of how the microscopic details of the building blocks affect the behaviour of the resulting macroscopic material particularly complex. The last years have seen a growing interest into non-spherical particles, which have shown to exhibit very interesting properties that has been linked to countless technological applications. As a result, several new sophisticated techniques for particle synthesis have been developed and refined. These recent advances allow for the creation of an immense variety of non-spherical building particles. Anisotropy can arise from shape, surface patterning, inter-particle interactions or a combination thereof. Huge theoretical and numerical efforts have only scratched the surface of the possible phenomena that can occur in systems composed of these exotic building blocks, let alone established the link between microscopic anisotropy and macroscopic phase behaviour. The main objective of my project was to explore the effect of different kind of anisotropies on the thermodynamics and dynamics of these new materials. My contribution has been to investigate the collective behaviour of both toy and realistic models of anisotropic particles. I have found strong connections between the dynamics and thermodynamics of simple spheres decorated with attractive patches, the so-called patchy particles, and the behaviour of more realistic systems such as water and molecular glasses. In addition, I have also investigated the phase behaviour of systems made entirely of DNA. In fact, the advances in DNA nanotechnology and in the synthesis of DNA-based materials call for the development of numerical and theoretical methods for the evaluation of their macroscopic properties. In my contribution, I helped developing a theoretical approach to predict the thermodynamic behaviour of particles made entirely of DNA, called DNA nanostars. I have also participated in a joint experimental/numerical effort to measure and interpret the inner structure of hydrogels made of DNA. Our results shed light on the dependence of the phase behaviour on temperature and salt concentration, providing guidance for future experimental work. The multidisciplinary character of the research I have carried out, which pertains to physics, physical chemistry, material science and nanotechnology, will reach different communities. Indeed, the different nature of the systems I studied, which ranges from colloids to DNA, are relevant to many diverse fields.

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