Gels and Soft Glass Transition
Recent experimental and theoretical advances have allowed a combined look at the rheology of the glass transition as compared to gelation, and to find universal rheological patterns that govern these phenomena. One such finding is that the relaxation time spectrum of a variety of gels and glasses consistently reduces into a powerlaw format, in which gels adopt a negative and glasses a positive powerlaw exponent. The finding is empirical for gelation and for molecular glasses but has theoretical backing through the mode coupling theory for colloidal glasses. (It is fortunate that rheology can distinguish between gelation and vitrification!) The rheological understanding of the solidification behavior of amorphous materials is a major scientific challenge, but it is also of practical importance, since many industrial products and processes rely on the control of rheological properties near the transition from liquid to solid. Examples include drug release dynamics, ordered self-assembly, and mechano-chemistry. Further examples include sealants, crystallizing polymers, phase separating block co-polymers, coacervates, hydrogels, and waterborne paints.
Professor Winter provides an overview of his work in this area and its importance across different industries, applications, and processes.