Nanoscale Spatio-Temporal Glassy Dynamics

Northeastern University, Boston MA

Investigators

Abstract

This individual investigator award will support a project to investigate the complex dynamics of glassy systems using scanning probe microscopy. In particular fluctuations on nanometer length scales of dielectric and visco-elastic properties as a function of frequency, time, position, electric field, and temperature in polymers and super-cooled liquids will be studied. The goals of the work are to probe individual cooperatively-rearranging-regions (CRR), to understand their structure, detailed dynamics, and their role in glassy phenomena. In addition, nonequilibrium fluctuations will be investigated in aging glassy materials. Theoretical work has predicted that the fluctuation-dissipation-relation will be violated in a model-dependent way in slowly relaxing systems such as glasses. The experiments will investigate the frequency, temperature, and aging-time dependences of these violations in super-cooled liquids and polymers, and thereby constrain theories of the glass transition and aging and advance our understanding of nonequilibrium statistical mechanics. The graduate students involved in this research will be trained in skills that will enable them to pursue future careers in academe or the high-technology industries. In addition, through undergraduate-research-fellowships, cooperative-education, and experiential-education programs, undergraduates will participate in this research, gaining valuable nanoscience experience and preparing them to contribute to important nanotechnologies of the future. When studying the properties of a material by probing ultra-small regions (nearly as small as a molecule), it has been found that properties such as hardness, elasticity, or electrical conductivity can vary considerably from nano-region to nano-region or with time. As nanotechnology is developed over the next few years, these variations will be increasingly important to understand. Nano-properties are also key to a fundamental understanding of disordered materials. Materials such as glass, polymers (plastics), and some metal alloys are called disordered because their molecules are randomly arranged. This individual investigator award will support a project to use advanced scanning probe microscopy techniques to investigate nano-property variations in disordered materials. These studies will advance our understanding of this important but poorly understood class of materials. The graduate students involved in this research will be trained in skills that will enable them to pursue future careers in academe or the high-technology industries. In addition, through undergraduate-research-fellowships, cooperative-education, and experiential-education programs, undergraduates will participate in this research, gaining valuable nanoscience experience and preparing them to contribute to important nanotechnologies of the future.