Crystallization and glass formation in colloidal-hydrogel suspensions

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

Non-Technical Abstract Advances in synthetic, experimental and modeling/simulation methodologies have considerably enhanced our understanding of materials. Yet, despite this remarkable progress, many outstanding challenges remain in our quest to understand how the properties of the basic material units or particles determine the properties at the macroscale. This work uses small soft particles to address this question. In particular, the project aims at understanding how single-particle deformability and compressibility affect formation of ordered and disordered solids. The research involves graduate and undergraduate students, and provides materials for enhancing existent soft matter physics courses, both at the theoretical and laboratory-work levels. We also exploit the natural connection between the science we address and food and cooking, to bring the research to the general public; this is achieved by bringing chefs and scientists together and organizing outreach events that include talks and demos by the speakers. Technical Abstract This project uses colloidal hydrogels as model soft particles to address (i) the formation of disordered solids and how it depends on the single-particle softness, and (ii) elucidate how size mismatch and polydispersity affect crystallization in soft-particle suspensions. One focus is the relation between glass formation and jamming, and whether these are distinct mechanisms, and if so, in which way and in what parametric range are they at play, for formation of disorder solids made of colloidal hydrogels. Another focus is to unravel the relation between fragility, which quantifies the way the liquid approaches the glass, and single-particle elasticity. The third focus is to elucidate the mechanism enabling crystallization of polydisperse colloidal-hydrogel suspensions. Ultimately, the overarching goal of this research is to understand and eventually exploit how single-particle softness affects macroscopic behaviour. The techniques employed include 3D-static light scattering, as well as small angle neutron and X-ray scattering, to quantify the structure of the suspension, 3D-dynamic light scattering and rheology, to quantify the dynamics at different time and length scales, and osmosis, to determine the suspension osmotic pressure, an important state function for colloidal systems. The experimental work is complemented with computer simulations and numerical calculations.