Structure Design Of Graphene Oxide-based Composite Films And Their Responsing Actuation Performence

The evenly distributed Graphene oxide(GO)aqueous solution with adjustable concentration is identified as the most basic raw materials for the preparation of graphene-based films with layered structure.Thin film deposition techniques that based on the GO aqueous solution are also being renewed and improved.In addition,a reduced graphene oxide(RGO)film with favorable electrical conductivity can be obtained through the reduction of as-prepared GO film,which is a very simple operation,and the layered microstructure of the GO-based film precursor will be maintained.Due to the numerous of excellent properties of GO and graphene,they have shown great potential and advantages in the smart actuation system.Asymmetric structure,bilayer or multilayer composite structures have been designed to endow the GO and graphene based film with smart actuation triggered by various environmental stimuli.In this study,the preparation and reduction of GO film with different methods,the fabrication and responsing performance of GO-based Janus film were carried out by the following parts.1.The inproved Hummers method was adopted to obtain the GO aqueous solution with uniform dispersion.Then several GO films with layered structure were prepared through interfacial self-assembly,evaporation-induced assembly and vacuum filtration methods,respectively.The RGO films with the higher thermal conductivity and the lower the resistances were also obtained by thermo-compression,thermal decomposition,and chemically HI-reduction methods,respectively.The characterization results show that the vacuum filtration could give rise to a more uniform structure and well mechanical properties of the GO film,and the film thickness manipulation is easy to operate,thus turn it into the most efficient technology for preparing GO film.In addition,the RGO film obtained by HI-reduction can keep the film integrity,and meanwhile improve the thermal/electrical conductivity of the original GO film,so as to achieve the best reduction effect.2.On account of the water absorption and desorption specialities of GO and RGO are quite different,the GO/RGO Janus film with environmental stimuli-responsiness was designed and febraciated successfully.The resultant film exhibited rapid response to humidity and temperature,accompanied by reversible crimping and bending actuations.Morever,the structure optimization provided the GO/RGO Janus film with an improved sensitive and response capacity to intelligent actuating behavior,which could be triggered by a sweaty or warm hand.Since the obtained RGO layer created with HI-reduction exhibited favorable electrical conductivity,a "smart perceptual switch" based on the GO/RGO Janus film was developed to switch a bulb on/off triggered by the moist-air supply or a sweaty hand.3.Based on the design of Janus structure,a variety of GO/polymer composite films with responsiveness to environmental stimuli have been developed,including the GO/PEBA,GO/PA and GO/PC composite films.These kind of smart actuators have revealed varying degree of response capacity,which was affected by the deifferent nature between GO layer and the polymer layer.The thermal/mosture stimulus-responsing test results suggested that the stimulus responsing capacity of the GO/PEBA Janus film was weak,while the GO/PA and GO/PC Janus film shown the similar responsing performance.However,the GO/PC Janus film was able to achieve the higher maximum bending angle under the same test condition,which cold be attributed to the more apparent differentces of the hygroscopic expansion and the drying shrinkage process between the GO layer and the PC layer.Finaly,the "octagonal" and "claw" intelligent actuators based on the GO/PA and GO/PC Janus film,respectively,could imitate the standing and graping behaviors under the thermal and mositure stimuli.