# Presentation: 774642

## Application of Dynamic Spectroscopic Methods to the Rheo-Optical Study of Polymers John F. Rabolt (University of Delaware) and Bruce Chase (DuPont)DMR 0315461

- The correlation between changes in the macroscopic properties of polymeric materials and changes at the molecular level presents a  challenge to the experimentalist.  The coupling of infrared absorption spectroscopy with dynamic mechanical analysis (DMA) offers just such a connection.  Whereas, vibrational spectroscopy is sensitive to molecular structure and orientation, DMA provides information on the elastic and viscoelastic properties of a material under cyclic strain. The limitation of previous efforts in this field has been the ***time*** required using step-scan FT-IR.  We have demonstrated dynamic infrared measurements on isotactic polypropylene (IPP) films during a strain cycle using a newly developed planar array IR (PA-IR) technique.  The comparison with FT-IR results is excellent with measurement times ***reduced by two orders of magnitude***.  Good S/N PA-IR spectra can be obtained in less than ***one second*** measurement time, yielding information at any point during the stress-strain cycle, and providing a detailed molecular picture of the IPP side chain (-CH3) and backbone response to strain.

*Applied Spectroscopy*., **2004**, 58, 799.

- PA-IR and FT-IR spectra of Dynamic Measurements on IPP

- Dynamic PA-IR Measurements at Intermediate Points During a Stress/Strain Cycle for the 1167 cm-1 C-C Stretch

## Application of Dynamic Spectroscopic Methods to the Rheo-Optical Study of Polymers John F. Rabolt (University of Delaware) and Bruce Chase (DuPont)DMR 0315461

- Since the DMA/PA-IR instrument has shown such promise in our earlier studies, Dr. Christian Pellerin, a postdoc partially supported on this grant, developed a teaching/demonstration module for a graduate class, Analytical Methods in Materials Science. This module gives students a chance to compare and understand the concepts of single channel, multi channel and multiplex measurements.  Twenty-three students (graduate and upper undergraduate) from Materials Science and Engineering, Chemical Engineering and Chemistry took this course in F04.
- Danielle Rockwood, a third year graduate student supported on this grant, made initial DMA/PA-IR measurements on a polyurethane-polycaprolactone copolymer (from Prof. Kim Woodhouse, Toronto) in order to evaluate its long term ageing characteristics and deformation mechanisms.   Electrospun membranes of this material are currently under investigation for use in an elastomeric ***heart patch. ***

**Outreach**
- Danielle Rockwood, a third year graduate student supported on this grant, spent two 2-week periods at the University of Toronto educating our collaborators on the importance of structure/processing/property relationships for the design a polyurethane-polycaprolactone copolymer high surface area membranes for biomedical applications.
- Because of its uniqueness, the DMA/PA-IR instrument for characterizing the dynamical behavior of polymers with molecular deformation was considered by an undergraduate/graduate class in “Entrepreneurship and Risk”, taught jointly by the College of Engineering (the PI-Rabolt was one of the instructors) and the College of Business as a candidate for a high technology startup company.  This PBL class (total enrollment 55 students) coupled 3-4 engineers with 2 MBA students in a team to write a technical/business plan for 9 such “virtual” companies and give an 8-minute presentation before a VC.  During the day many of the engineers and MBA students were employed in companies located in DE, MD, PA and NJ.

*Application of Dynamic Spectroscopic Methods to the Rheo-Optical Study of Polymers **John F. Rabolt (University of Delaware) and Bruce Chase (DuPont)**DMR 0315461*