Multidimensional Structure Design, Preparation And Property Of Actuator

Mechanical actuators exhibiting reversible shape changes in response to environmental stimuli,such as light,thermal,electrical,or chemical energy,have attracted much attention.This is because of their potential in environment-triggered sensors,artificial muscles,and electromagnetic-free generators.Various actuators including liquid crystal elastomers,dielectric elastomers,ionic polymer-metal composites,and carbon nanotube actuators have been developed.However,such mechanical actuators have inherent limitations.Their principle actuation mechanisms have been attributed to stimuli-induced chemical reactions,electrically controlled ion/solvent transport,or thermal expansion.Thus,they require complex chemical systems,external power supplies,or distinct temperature changes,which limits their application.They are also often single-triggered,and exhibit slow responses,small-scale movement,and low stress generation.Faced with these problems,based on a variety of nano-materials with environmental responsiveness,a series of multi-driven?moisture,thermal,electrical,chemical and so on?actuator were developed through adjusting micro-nano structure.It mainly included the following parts:A graphene monolayer?GM?paper with a gradient reduced graphene oxide/graphene oxide?rGO/GO?structure was fabricated using an economical,scalable,low temperature and environmentally friendly process.GO exhibits strong water absorption/desorption capability,and rGO is strongly hydrophobic.Both GO and rGO exhibit good photothermal heating effects.These properties are exploited to yield GM paper with reversible,fast?,0.3 s?,powerful(3.1 W kg^-1 work output),and controllable mechanical deformation and recovery,in response to moisture,heat,and light.The response of this water-driven actuator to multiple stimuli allows the artificial muscles and electric generators to be fabricated.The GM paper can be produced on large scales?i.e.many meters?,which promotes its practical application.An instant self-folding graphene paper with a programmed dualgradient?vertical and lateral?structure is developed to address many of the issues facing self-folding structures described above.That is,we usefunction-designed graphene oxide?GO?nanoscale building blocks to fabricate a self-folding all-graphene paper that represents both a single-component gradient structure and a functional device that demonstrates three capabilities:producing predesigned shapes,walking,and turning a corner.The performance of this paper can be remote-controlled by exposure to gentle light or heat.We propose and develop an easy and efficient method to fabricate a hierarchically wrinkled elastic transparent conductor?HWETC?via a“balloon-blowing”method.Unlike previous elastic transparent conductors that were prepared using 1D or 2D stretching methods,our HWETC structure exhibits typical short-and long-period wrinkles that occur reversibly out of phase in the multiaxial directions.Because of the periodic hierarchical wrinkling of the r GO layer,the HWETC demonstrates high conductivity?<500?/??and transmittance under substantial stretching?>400%?.Various potential applications for HWETCs,including use as artifcial muscles and in sensors,are suggested by the results.In addition,inspired by biological membrane molecular channel,a commercially available polymer,perfluorosulphonic acid ionomer?PFSA?film is studied as a kind of intrinsically deformable vapor driven actuators,with numbers of nanoscale molecular channels and biphasic?hydrophilic phase and hydrophobic phase?coexistence.In-situ grazing incidence wide angle X-ray scattering?GIWAX?was applied to investigate the microstructure evolution with the vapor exposure and further clarify the deformation mechanism.A series of ultra-fast vapor driven monolayer and bilayer actuator has been developed by a simple and practical process,exhibiting extremely rapid response?0.25 s for one curl?and ultra-stability?>80,00times without deterioration?.Multi-dimension actuation,including two-dimensional bending actuation as well as three-dimensional helical actuation with twisting/untwisting and elongation/contraction deformation capability,was obtained via interfacial structure design.The kirigami-inspired mono-layer actuator was developed for personal humidity and heat management system through macroscale geometry design,and a bilayer stimuli-responsive actuator with the multi-color switch was invented through surface chemical modification.This vapor-deformable micro-actuator is expected to have broad application prospects in human-interfacial applications,e.g.personal wet and heat management smart cloth,low observable technology,and artificial intelligence.