What makes a material a solid? Crystalline materials have their atoms and molecules organized into neatly repeating patterns — breaking up these repeating patterns costs energy, and the result is a material that resists deformation, that is, one that is solid. Glassy materials — which can be made from silica as in ordinary window glass but also many other polymeric, molecular, or colloidal liquids — are quite different: unlike orderly crystals their components are disordered, and their viscosity can vary enormously when their temperature is varied very slightly. Almost all disordered materials follow two characteristic patterns for the precise way that their dynamics slow down, leading to a categorization of glasses as either “fragile” or “strong.” Very recently there has been evidence of a third type of glass, an “ultra-strong” glass, whose dynamics and material properties would be much less sensitive to changing temperature than strong or fragile glasses. This unusual type of glass has, so far, been observed in two seemingly disconnected systems: computational models of dense epithelial tissue (tissue that covers all body surfaces and line body cavities) and of low-density vitrimers (a type of plastic material).
The National Science Foundation has awarded a CAREER grant to Prof. Sussman to understand this new class of materials, using a systematic combination of extensive computational modeling together with an effort to build a theoretical description of ultra-strong glasses. At its core, this research seeks to address two primary questions: 1.) What is the fundamental nature of an ultra-strong glass? 2.) What features of a physical system lead to it? This project also supports educational and outreach activities that are closely integrated with the research project.