Past Seminars Seminários Já Decorridos 2013

Self-assembly of patchy particles: chains, rings, branches and bigels.

By: José Maria Tavares
From: CFTC-UL and ISEL
At: Instituto de Investigação Interdisciplinar, Anfiteatro
[2013-11-27] 11:00

The competition between self-assembly and phase separation in fluids with anisotropic interactions is investigated using several models of patchy particles. The type of aggregates onto which particles self assemble is controlled by the number of patches in each particle,  their sizes, shapes and interaction energies.

We use Wertheim's first order perturbation theory (augmented to include the possibility of ring formation) and a generalized version of the Flory-Stockmayer percolation theory, to obtain the thermodynamics and structure of these models.

The phase diagrams of models with a competition between self-assembling in chains, rings and branched structures are shown to have several unusual features, like re-entrant liquid and vapor binodals and two critical points. The comparison with results of Monte Carlo simulations for the same models validates the predictions of the theory.

We also investigate the structure of  a binary mixture of patchy particles and identify four distinct percolated phases: two gels (where only one of the species is percolated), a mixed gel (where the two species are percolated but neither of them is percolated by itself) and a bigel (where the two species percolate independently, forming two interpenetrating spanning networks).