Gelation and glass transitions of colloidal particles are common phenomena in everyday life. However, the understanding of the physics mechanisms for the gelation and glass transitions are very limited, and necessitates continued efforts to investigate them at a wide range of length and time scales. On the other hand, many interesting structures formed during the gelation/glass transition have been useful for industrial applications, and can be controlled by tuning the effective interaction potential between colloidal particles.

One example of the self-assembled gel system is the formation of Bijel by dispersing neutrally wetted particles in a binary solvent that can form bicontinuous structures. However, it is more common to find particles that are preferentially wetted by one component of the binary solvent, which we have been studying recently and found that they form different type of structures compared with Bijel systems. Even for particles in a one-component solvent, interesting structures have been found for gel states too. For example, recent interests in model systems with both a short-range attraction and a long-range repulsion (SALR) have led to the discovery of the intermediate range order in liquid and glassy states. It should be noted that the general understanding of SALR systems are beneficial to biological and pharmaceutical applications as many proteins systems are SALR systems too.

The goal of this project is to study the structure and dynamics of colloidal particles in liquid and during the transition to the gel/glass states, and how to control the self-assembled colloidal structures by tuning the properties of particles and solvents. Many different techniques will be used to study these gel systems. For example, small angle neutron scattering, neutron spin echo, and rheometers can be used to understand both the structural and dynamic properties of the systems undergoing the gel/glass transition. We are also interested in how external conditions affect the structure, such as the shearing force and AC electric fields.