Contactless, Photoinitiated Snap-through In Azobenzene-functionalized Polymers

Authors

M. Ravi Shankar, University of Pittsburgh - Main Campus
Matthew L. Smith, Hope CollegeFollow
Vincent P. Tondiglia, Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base
Kyung Min Lee, Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base
Michael E. McConney, Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base
David H. Wang, Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base
Loon-Seng Tan, Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base
Timothy J. White, Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base

Document Type

Article

Publication Date

11-19-2013

Publication Source

Proceedings Of The National Academy Of Sciences Of The United States Of America

Volume Number

110

Issue Number

47

First Page

18792

Last Page

18797

Publisher

National Academy of Sciences

ISSN

0027-8424

Abstract

Photomechanical effects in polymeric materials and composites transduce light into mechanical work. The ability to control the intensity, polarization, placement, and duration of light irradiation is a distinctive and potentially useful tool to tailor the location, magnitude, and directionality of photogenerated mechanical work. Unfortunately, the work generated from photoresponsive materials is often slow and yields very small power densities, which diminish their potential use in applications. Here, we investigate photoinitiated snap-through in bistable arches formed from samples composed of azobenzene-functionalized polymers (both amorphous polyimides and liquid crystal polymer networks) and report ordersof- magnitude enhancement in actuation rates (approaching 10(2)mm/ s) and powers (as much as 1 kW/m3). The contactless, ultra-fast actuation is observed at irradiation intensities << 100 mW/cm(2). Due to the bistability and symmetry of the snap-through, reversible and bidirectional actuation is demonstrated. A model is developed to elucidate the underlying mechanics of the snap-through, specifically focusing on isolating the role of sample geometry, mechanical properties of the materials, and photomechanical strain. Using light to trigger contactless, ultrafast actuation in an otherwise passive structure is a potentially versatile tool to use in mechanical design at the micro-, meso-, and millimeter scales as actuators, as well as switches that can be triggered from large standoff distances, impulse generators for microvehicles, microfluidic valves and mixers in laboratory-on-chip devices, and adaptive optical elements.

Keywords

Author Keywords: photochemistry; elastic instability KeyWords Plus: NETWORKS; ISOMERIZATION; ELASTOMERS; DEVICES

Recommended Citation

Shankar, M. Ravi, Matthew L. Smith, Vincent P. Tondiglia, Kyung Min Lee, Michael E. McConney, David H. Wang, Loon-Seng Tan and Timothy J. White. "Contactless, Photoinitiated Snap-through in Azobenzene-Functionalized Polymers." Proceedings Of The National Academy Of Sciences Of The United States Of America 110, no. 47 (2013): 18792-18797.