Photoresponsive
materials based on azobenzene (Azo) and its derivatives
have attracted wide attention because the cis-trans isomerization of Azo under illumination often leads
to changes in shape, color, size, polarity, and so on; it has great
application potential in soft robot, actuator, sensor, and other fields.
In this paper, by using evaporation-induced self-assembly method,
taking advantage of the hydrogen bonding among chitosan (CS), polyvinyl
alcohol (PVA) and Azo, and by polishing and grinding the surface of
the adopted silicon film mold in advance to form grooves, the Azo/CS/PVA
film with a certain degree of oriented aggregation convex surface
was prepared. The film has good deformation characteristics of dual
response of light and humidity. Also, it has excellent light response
direction controllability under UV light, sunlight, and LED illumination.
By studying the structure, morphology, photo-stimulus response behavior,
humidity-photo response behavior, and mechanical properties of the
films, it is found that when the Azo content reaches 10% wt, the response
speed is the fastest and the response deformation is the largest.
The result shows that under the irradiation of summer sunlight (sunny
day), the film can reach 144°directional bending within 55 s.
Moreover, the film has excellent humidity response performance, which
can absorb sweat in the fingertips, deform quickly, and recover quickly
after leaving fingers. The film with an Azo content of 10% wt has
a fast humidity response speed, and the maximum bending angle is 140°.The
designed simple sunlight response driver can lift a heavy object five
times heavier than itself to a certain height, and realize the effective
conversion from light energy to mechanical energy. This work effectively
broadens the application range of bio-based environmentally friendly
materials and has guiding significance for the development and design
of multi-stimulus response intelligent materials. The light response
directional control method is simple and practical. It is of great
significance for the effective utilization of solar energy.