ma7b01741_si_006.avi (7.72 MB)
Photomechanical Motion of Liquid-Crystalline Fibers Bending Away from a Light Source
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posted on 2017-10-19, 17:32 authored by Zhangxiang Cheng, Shudeng Ma, Yihe Zhang, Shuai Huang, Yuxuan Chen, Haifeng YuA series
of photomechanical fibers was fabricated with a thermal
drawing method by using liquid-crystalline random copolymers containing
azobenzene and biphenyl groups in side chain. After being post-cross-linked
under mild conditions, these fibers showed photoinduced bending motion
away from the light source even though homogeneous alignment of mesogens
was observed along the drawing direction. This abnormal photoinduced
deformation of the obtained fibers is far different from previously
reported light-directed motions about liquid-crystalline fiber and
film materials. The interesting photomechanical deformation can be
ascribed to the surface volume expansion caused by photoisomerization
of azobenzene moieties. Then the photoinduced bending behaviors of
these fibers containing different azobenzene concentrations and cross-linking
densities were systematically investigated, suggesting that the location
of photoresponsive azobenzene played an important role in deciding
their photomechanical behaviors. This provides one convenient way
of controlling over the photoinduced bending direction through the
location of light-active moieties in side chain or cross-linker. In
addition, irradiation of visible light accelerated the recovery of
bent fibers. These fibers possess quick response, large deformation,
and good thermal stability, indicating their promising applications
for smart devices and energy conversion devices.