Research Investigação

DFT theory of inhomogeneous mixtures of Lisbon patchy colloids: interfacial gels

Using Wertheim's theory and a generalization of the Flory-Stockmayer's theory of polymerization we investigated the bulk phase diagram and the connectivity of binary mixtures of Lisbon patchy colloids, where each species is decorated by sites of two types. One of these types promotes bonds between identical species, and the other favours bonding between unlike species. We have found a rich phase diagram and discovered four different gels: two standard gels (where the mixture is percolated but only one species remains percolated if the inter-species bonds are broken), a mixed gel (where the mixture is percolated but neither species remains percolated if the bonds between species are broken) and a bicontinuous gel (where the mixture and both species are percolated separately). These novel systems are interesting as the percolation state of the system may be tuned by varying the temperature, pressure or composition of the mixture, paving the way for a range of applications that exploit its connectivity. When the dimensionality is reduced, as required by some applications, the effect of surfaces and interfaces may dominate.

Mixed gel, bigel, gel and gel.

Here we investigate the interfacial (liquid-liquid interfaces) and surface properties of mixtures of Lisbon patchy colloids by means of density functional theory (DFT). We will use different approximations for the excess free energy (that accounts for the excluded volume interaction between the hard-cores and the bonding free energy), such as the fundamental measure theory.