publications

2023

1. On kinetic constraints that catalysis imposes on elementary processes

   Yann Sakref, Maitane Muñoz-Basagoiti, Zorana Zeravcic, and 1 more author

   The Journal of Physical Chemistry B, 2023

   Abs

   Accepted for publication, 2023

2. Computational design of a minimal catalyst using colloidal particles with programmable interactions

   Maitane Muñoz-Basagoiti, Olivier Rivoire, and Zorana Zeravcic

   Soft Matter, 2023

   Abs arXiv

   Catalysis, the acceleration of chemical reactions by molecules that are not consumed in the process, is essential to living organisms but currently absent in physical systems that aspire to emulate biological functionalities with artificial components. Here we demonstrate how to design a catalyst using spherical building blocks interacting via programmable potentials, and show that a minimal catalyst design, a rigid dimer, can accelerate a ubiquitous elementary reaction, the cleaving of a bond. By combining coarse-grained molecular dynamics simulations and theory, and by comparing the mean reaction time in the presence and absence of the catalyst, we derive geometrical and physical constraints for its design and determine the reaction conditions under which catalysis emerges in the system. The framework and design rules that we introduce are general and can be applied to experimental systems on a wide range of scales, from micron size DNA-coated colloids to centimeter size magnetic handshake materials, opening the door to the realization of self-regulated artificial systems with bio-inspired functionalities.

2022

1. Self-assembly of emulsion droplets via programmable folding

   Angus McMullen*, Maitane Muñoz-Basagoiti*, Zorana Zeravcic, and 1 more author

   Nature, 2022

   Abs arXiv

   At the cutting edge of materials science, matter is designed to self-organize into structures that perform a wide range of functions. The past two decades have witnessed major innovations in the versatility of building blocks, ranging from DNA on the nanoscale to handshaking materials on the macroscale. Like a jigsaw puzzle, one can reliably self-assemble arbitrary structures if all the pieces are distinct, but systems with fewer flavors of building blocks have so far been limited to the assembly of exotic crystals. Inspired by Nature’s strategy of folding biopolymers into specific RNA and protein structures, here we introduce a minimal model system of colloidal polymers with programmable DNA interactions that guide their downhill folding into two-dimensional geometries. Combining experiments, simulations, and theory, we show that designing the order in which interactions are switched on directs folding into unique geometries called foldamers. The simplest alternating sequences (ABAB...) of up to 13 droplets yield eleven foldamers, while designing the sequence and adding an extra flavor uniquely encodes more than half of the 619 possible geometries. These foldamers can further interact to make complex supracolloidal architectures, seeding a next generation of bio-inspired materials. Our results are independent of the dynamics and therefore apply to polymeric materials with hierarchical interactions on all length scales, from organic molecules all the way to Rubik’s snakes.

2020

1. Electrostatics and domains in ferroelectric superlattices

   Daniel Bennett, Maitane Muñoz-Basagoiti, and Emilio Artacho

   Royal Society Open Science, 2020

   Abs arXiv

   The electrostatics arising in ferroelectric/dielectric two-dimensional heterostructures and superlattices is revisited within a Kittel model in order to define and complete a clear paradigmatic reference for domain formation. The screening of the depolarizing field in isolated ferroelectric or polar thin films via the formation of 180 degree domains is well understood, where the width of the domains w grows as the square-root of the film thickness d, following Kittel’s Law for thick enough films (w < d). For thinner films, a minimum is reached for w before diverging to a monodomain. Although this behaviour is known to be qualitatively unaltered when the dielectric environment of the film is modified, we consider the quantitative changes in that behaviour induced on the ferroelectric film by different dielectric settings: as deposited on a dielectric substrate, sandwiched between dielectrics, and in a superlattice of alternating ferroelectric/dielectric films. The model assumes infinitely thin domain walls, and therefore is not expected to be reliable for film thickness in the nanometre scale. The polarization field P(r) does vary in space, deviating from Ps, following the depolarizing field in linear response, but the model does not include a polarization-gradient term as would appear in a Ginzburg–Landau free energy. The model is, however, worth characterizing, both as paradigmatic reference, and as applicable to not-so-thin films. The correct renormalization of parameters is obtained for the thick-film square-root behaviour in the mentioned settings, and the sub-Kittel regime is fully characterized. New results are presented alongside well-known ones for a comprehensive description. Among the former, a natural separation between strong and weak ferroelectric coupling in superlattices is found, which depends exclusively on the dielectric anisotropy of the ferroelectric layer