Modelling the impact of processing conditions on the kinetics of self assembly of soft multicomponent materials: effects of shear flow

I aim at developing conceptual and mathematical models for the thermodynamic and momentum, heat and mass transfer mechanisms that determine the self-assembly of edible multicomponent systems subject to different external fields (temperature profiles, shear and extensional flow, etc.). Shear flow is used very empirically in industry to obtain desired structural properties, but little fundamental knowledge exists. This application focuses on crystallization of multicomponent lipid systems prepared with pure components. This will somewhat simplify the complexity from the multicomponent nature and the polymorphism of these materials: even a pure component can form different solid phases. Studies at high temperature will look at the initial steps when the particles are nanometres in size, because they are crucial to the spatial distribution of particles, that will impact all the crystallization mechanisms occurring at later stages. Studies at lower temperatures will include polymorphic transformations. Models based on fundamental mechanisms and amenable to work under flow and variable temperature are required. Yet, the few models used in the literature do not have that flexibility. I recently developed a successful model for the crystallization of palm oil and milk fat under shear (e.g. Phys. Rev. E. 71, 041607, 2005), and propose to examine the hypotheses proposed with that model: impact of particle segregation on growth/nucleation ratios, acceleration of polymorphic transformations by secondary nucleation of undercooled liquid, and layered crystallization. To examine these hypotheses we require measurements that integrate several methods to provide quantitative phase distribution, particle characteristics and mechanical properties in-situ and in real time. We will combine NMR, rheology and synchrotron XRD. Done simultaneously these measurements will mean a breakthrough in the study crystallization kinetics of multi-phase systems. The findings will be very useful for aggregation processes in other materials as well since the lipid molecules have sizes between large polymers and small compounds.