Photomechanical Effects in Azo-Polymers Studied by Neutron Reflectometry

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TypeArticle
Journal titleMacromolecules
Macromolecules
ISSN0024-9297
Volume39
Issue26
Pages93119319; # of pages: 9
AbstractNeutron reflectometry is used to study photomechanical effects in thin films of azobenzene polymer cast onto silicon substrates. A significant photoexpansion effect, up to 17%, is observed at 25 C, due to the free volume requirement of the azobenzene chromophore photoisomerization. Above a distinct crossover temperature of ~50 C, the material response is inverted and instead photocontraction effects, of more than -15%, are observed. In this case the combined photomotion and thermal mobility enables aggregation and crystallization of the azobenzene dipoles. The photomechanical effects, which can be reversed, occur readily using a variety of irradiation powers, incident polarizations, and film thickness values. This photomechanical behavior, which appears to be general to all azo materials, is likely the origin for a wide variety of curious photomotions observed in these systems, including macroscopic bending of samples and micron-scale surface mass transport.
Publication date
Linkhttp://pubs3.acs.org/acs/journals/doilookup?in_doi=10.1021/ma0617320
AffiliationNational Research Council Canada; NRC Canadian Neutron Beam Centre
Peer reviewedNo
Identifier10061873
NPARC number12328670
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Record identifiereecae0d0-f627-4c85-a847-dfacdf4964b5
Record created2009-09-10
Record modified2016-05-09
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