Abstract
Light has been used to induce photochemical changes in the surface chemistry of porous polymer microstructures giving rise to a substantial change in volume. When illumination is asymmetric, this results in light-directed motion of the structure. Swellable trimethylolpropane trimethacrylate cross-linked poly(2-hydroxylethyl methacrylate) microstructures were constructed by azo-bis-isobutyronitrile photopolymerization using a 20 × 0.5 NA microscope objective and 365 nm laser excitation. Structures were aminiated with glycine and protected with the photolabile group 4-nitroveratryloxycarbanyl (NVOC). Addition of NVOC resulted in a volume increase >10% when performed in the solvent N,N′-dimethylformamide. Photochemical cleavage of NVOC using asymmetric illumination of a cone-shaped microstructure with a 365 nm laser induced polymer shrinkage in excess of 4% at the base of the cone and resulted in a maximum velocity of 1 mm/s at the tip of the cone. Symmetric illumination gave rise to displacement of solvent from the microstructure due to shrinkage with a velocity in excess of 0.01 mm/s. This system could in principle be used for light-directed movement of micromechanical systems, optical control of microfluidics, or light activated chemical delivery.
Original language | English (US) |
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Pages (from-to) | 4949-4953 |
Number of pages | 5 |
Journal | Langmuir |
Volume | 21 |
Issue number | 11 |
DOIs | |
State | Published - May 24 2005 |
ASJC Scopus subject areas
- General Materials Science
- Condensed Matter Physics
- Surfaces and Interfaces
- Spectroscopy
- Electrochemistry