Calendar Details

For more information about item submission and attendance, see About the Technical Calendar.

Tuesday, December 11

Mechanochemical Remodeling: From New Reactions to Adaptive Materials

Professor Steve Craig, Duke University, Durham, NC
University Partnerships Seminar
12:30 PM — 1:30 PM, Joint Institute for Computational Sciences (JICS), Building 5100, Room 262
Contact: Debbie Turner (turnerdk@ornl.gov), 865.576.7777

Abstract

The forces typical of the macroscopic world (for example, those between a baby's fingers) are many orders of magnitude larger than the forces between the individual atoms of a molecule. It has been known for decades, in fact, that breaking a piece of plastic or shearing a polymer solution can lead to homolytic carbon-carbon bond scission along the main chain of an organic polymer and a concomitant reduction in molecular weight. The magnitude of macroscopic forces, in combination with the fact that they are directional, creates a spectacular opportunity to direct chemistry that might otherwise be effectively impossible.

This talk will present studies of reactions under large, directional forces, and their applications in studies of fundamental reactivity and new classes of stress-responsive polymers. Specific outcomes include the ability to trap transition states for extended periods of time, molecules that get shorter in response to being pulled, and the nearly instantaneous and reagentless conversion of a single homopolymer into well-ordered diblock copolymers. Within materials applications, a new class of self-healing polymers will be introduced, in which mechanical activation of chemical reactions leads to improved structure and properties under conditions that are typically destructive to both.