I am presenting my research in the School of Chemistry at the University of Sydney on: “Microfluidic manipulation of Colloids and Polymers to create novel Functional Materials”.

Abstract:

Adapting and manipulating the components of a material to achieve the desired properties is an essential requirement for the study and the advancement of science and technology. The same approach is also the key to develop, for instance, new biocompatible materials to understand the bio-chemical mechanisms of cells behaviour.
In my seminar I will describe different approaches that I developed to manipulate suspended colloidal particles or polymers in constrained geometry. I will present the unexpected trapping phenomena that I recently unveiled and how the density and size of the solute can alter this behaviour. By exploiting the hydrodynamics in microfluidic geometry it is also possible to focus and order particles in specific positions, I will present evidences of the flow-field that guide particles by means of all optical methods. Also, by controlling the interface properties of two immiscible fluids, we discovered a novel and highly efficient method to obtain microemulsions to be used to produce monodisperse colloidal particles. Then, by imposing a temperature gradient, I have exploited thermophoresis to manipulate nano- and micro- colloidal particles. In particular, I have investigated how the size, the average temperature and the kind of electrolytes dispersed in solution can be used to control the magnitude and direction of the motion. Thermophoresis is present under thermal non-equilibrium conditions. Once a steady state is reached the temperature gradient is balanced by a concentration gradient. Recently, I was able to freeze this non-equilibrium condition by exploiting a polymerization process, thus obtaining a concentration gradient material. It is easy to tune its properties by controlling the characteristics of the concentration gradient of the solute. Preliminary results on the functionalised biocompatible calcium alginate hydrogel obtained by thermophoresis will be presented. In particular, I will show how its mechanical properties can be adjusted with a temperature gradient and how cells respond to them.