posted on 2022-12-05, 05:56authored byWen Wang, Shuying Liu, Shuang Wang, Chenxue Xiang, Yangjie Huang, Mufang Li, Dong Wang
As an important branch of intelligent materials, the
research and
development of stimulus-responsive flexible intelligent actuation
materials is of great significance to promote the industrialization
of intelligent materials. In this study, the asymmetric PVA-co-PE/silicon nanoparticle (PPSN) composite films and PVA-co-PE/silicon sol (PPSS) composite film with different silicon
distributions were prepared by a simple spraying method. The silicon
nanoparticle layer in the PPSN composite film was similar to the sand-like
water-absorbing layer, which can quickly absorb water and permeate
it into the interior region, leading to the hygroscopic expansion
behavior on one side of the nanofiber film. Then, the PPSN composite
film would quickly bend and deform to the silicon nanoparticle side.
However, in the PPSS composite film, due to the excellent hygroscopicity
and swelling characteristics of the silica sol layer, the composite
film can be rapidly deformed to the PVA-co-PE nanofiber
film side under moisture stimulation. The above results subvert the
traditional asymmetric actuation film, which mainly depends on the
hydrophilicity difference to determine the hygroscopic responsiveness
and deformation direction, and ignore that the swelling degree is
the main factor determining the bending direction of actuator. In
addition, both the composite films can quickly respond to moisture
stimulation (<1 s) and produce large-scale bending deformation
(180°). Furthermore, due to the excellent interface adhesion
formed by the continuity structure in the PPSS composite film, it
has better actuation stability than the PPSN composite film. The excellent
actuation characteristics and different bending directions of the
PPSN and PPSS composite films make it a great application prospect
in the field of bionics in the future.