Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session W11: Invited Session: Polymer Based Soft Materials: Industrial Applications
2:30 PM–5:30 PM,
Thursday, March 21, 2013
Sponsoring Units: DPOLY FIAP
Chair: Miriam Rafailovich, State University of New York, Stony Brook
Abstract ID: BAPS.2013.MAR.W11.1
Abstract: W11.00001 : Tuning the Photoinduced Motion of Glassy Azobenzene Polymers and Networks*
2:30 PM–3:06 PM
Preview Abstract Abstract
(Air Force Research Laboratory)
Continual innovation at the forefront of soft-matter, in areas such as liquid crystal networks, nano-composites and bio-molecules, is providing exciting opportunities to create smart materials systems that exhibit a controlled, reproducible and reversible modulation of physical properties. These material systems evoke the adaptivity of natural organisms, and inspire radical aerospace notions. A key example is photo-responsive polymers, which convert a light stimulus input into a mechanical output (work). Photoinduced conformational changes, such as within azobenzene, dictate molecular-level distortions that summate into a macroscopic strain, which often manifests as a shape change or motion. The transduction of the molecular-level response to a macroscale effect is regulated by mesoscopic features, such as chain packing, free volume, and local molecular order - factors which depend on chemical composition as well as the process history of the material. For example, physical aging increases the density of the glass, reduces local free volume, and thus decreases the minima in local conformation space which strongly influences the azobenzene photochemistry (trans-cis-trans isomerization). The subsequent change in the energy landscape of the system reduces the fraction of azobenzene able to undergo reconfiguration as well as increases the probability that those photoinduced conformations will relax back to the initial local environment. The result is a tuning of the magnitude of macroscopic strain and the ability to shift from shape fixing to shape recovery, respectively.
*Work done in collaboration with H. Koerner, K.M. Lee, M. Smith, D. Wang, L-S. Tan. and T. White, Air Force Research Laboratory.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2013.MAR.W11.1
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