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Science 10 June 2005:
Vol. 308. no. 5728, pp. 1615 - 1617
DOI: 10.1126/science.1110505
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Reports

Photoinduced Plasticity in Cross-Linked Polymers

Timothy F. Scott,1 Andrew D. Schneider,1 Wayne D. Cook,2 Christopher N. Bowman1*

Chemically cross-linked polymers are inherently limited by stresses that are introduced by post-gelation volume changes during polymerization. It is also difficult to change a cross-linked polymer's shape without a corresponding loss of material properties or substantial stress development. We demonstrate a cross-linked polymer that, upon exposure to light, exhibits stress and/or strain relaxation without any concomitant change in material properties. This result is achieved by introducing radicals via photocleavage of residual photoinitiator in the polymer matrix, which then diffuse via addition-fragmentation chain transfer of midchain functional groups. These processes lead to photoinduced plasticity, actuation, and equilibrium shape changes without residual stress. Such polymeric materials are critical to the development of microdevices, biomaterials, and polymeric coatings.

1 Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, USA.
2 School of Physics and Materials Engineering, Monash University, Clayton, Victoria 3800, Australia.

* To whom correspondence should be addressed. E-mail: christopher.bowman{at}colorado.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Towards electrically conductive, self-healing materials.
K. A Williams, A. J Boydston, and C. W Bielawski (2007)
J R Soc Interface 4, 359-362
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