| Start Date: | 10/25/2012 | Start Time: | 3:30 PM |
| End Date: | 10/25/2012 | End Time: | 4:30 PM |
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Event Description
The Department of Physics will host “Slow Dynamics and Topological Entanglement in Macromolecular Liquids” with Dr. Kenneth S. Schweizer, G. Ronald and Margaret H. Morris Professor of Materials Science and Engineering, University of Illinois at Urbana-Champaign, October 25, 2012 at 3:30 p.m. at Disque Hall, room 919 (32nd and Chestnut Streets).
Concentrated liquids of large synthetic and biological macromolecules display fascinating and unique slow dynamics of great importance in fields as diverse as the materials science and processing of molten plastics to cellular rigidity and biophysics. Two common features of all entangled linear polymers is their ability to interpenetrate (ala a bowl of cooked or uncooked spaghetti) but not dynamically cross each other. The combined consequences of these factors is called “topological entanglement”, and a fundamental understanding remains a major challenge in physics. Dr. Schweizer will first discuss key experimental phenomena and the reptation-tube model which postulates that at large enough times long polymers move like snakes corresponding to anisotropic diffusion along their own contour. As distinctive consequences, relaxation, diffusion and flow occur extremely slowly and rubber-like elasticity (ala silly putty or chewing gum) emerges on intermediate time and length scales. However, the reptation-tube theory lacks a microscopic foundation in terms of forces, and many fundamental questions remain unanswered such as the following. Where does the confining tube due to forces between different polymers really come from? What is the microscopic origin of the remarkable elasticity? Are entanglements effectively unbreakable? Building on recent advances for understanding slow dynamics in glass-forming liquids, Daniel Sussman and Schweizer have developed a fundamental theory for entangled polymers of different shapes (rods, random coils, and star-like branched crosses). The key ideas and new predictions that address the above questions will be described in detail for rigid rods, and quantitative comparisons made with simulations and biopolymer experiments. Time permitting, generalization of the approach to random coil flexible polymer chains will be briefly discussed.
The lecture is free and open to the Drexel community. For more information, email Dr. Shyamalendu Bose at bose@drexel.edu. |
Contact Information:
Name: Dr. Sam Bose
Phone: (215) 895-2718
Email: bose@drexel.edu |
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Location:
Disque Hall, room 919 (32nd and Chestnut Streets) |
Audience:
AlumniCurrent StudentsFacultyParents & FamiliesProspective StudentsPublicStaff |
Special Features:
Free FoodGiveawaysOnline AccessCEU Available |
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