Study On The Preparation Of Biomimetic Functional Films And Intelligently Driven Behavior

In recent years,with the scientific development of bionics and material interface,further researches of surface engineering provide a number of novel ideas and methods for the design and exploitation of stimulus-response driving devices.At present,the driving materials are mainly divided into three types: surface functional materials,bulk materials and multistage structural materials.The polymer brush could be extensively used to regulate the physicochemical properties of the surface,construct various surface with different structures,functions and inorganic/organic hybrid materials,which attribute to its excellent modifiability,and by the method of Surface Initiated Polymerization(SIPs).Modifying the surface of soft materials with polymer brushes such as temperature-sensitive and humidity-sensitive can achieve an ideal response driving effect.In addition,the graphene oxide,a kind of two-dimensional material with high specific surface area,possessing excellent thermal,electrical,mechanical,and optical properties also can be a promising candidate for fabricating actuation devices.In this paper,through the surface modification method,using the temperature-sensitive and humidity-sensitive response characteristics of polymer brushes,the PDMS(polydimethylsiloxane)film was modified on one side and asymmetric on both sides,respectively,and various actuators were developed.In addition,graphene oxide(GO)was used as the photothermal driving layer and PDMS was used as the driven layer.Using the difference in thermal expansion coefficients between GO layer and PDMS layer,a driving film with fast light response characteristics was prepared.The main contents as follow:(1)PDMS film was modified on one side with temperature-sensitive polymer brush PNIPAAM(Poly N-isopropylacrylamide)and moisture-sensitive polymer brush PSPMA(Poly 3-Sulfopropyl methacrylate potassium salt)through surface initiated-atom transfer radical polymerization(SI-ATRP),which could obtain two driving films with humidity and temperature response characteristics,respectively.At the same time,the corresponding test characterization and driving mechanism explanation have been completed.It lays the foundation for the research of asymmetric polymer brushes modified films.(2)Based on the research in the previous chapter,an asymmetric polymer brushes modified driving film was prepared,which further improved the response nature of temperature and humidity.In addition,we found that under high humidity,the film exhibited a novel orthogonal bending behavior.Based on this,we developed a smart gripper that could quickly pick up and release object which are five times their own weight in 2s.In addition,this film is highly sensitive to humidity that even the approaching finger just could make it to bend.Based on this,we also designed smart humidity sensor and bionic plant inspired by mimosa.(3)A significant difference in thermal expansion coefficients between the PDMS layer and the GO layer was used to successfully prepare a light-responsive driving film with in-built porous structure.The film can exhibit different bending states under the stimulation of near-infrared light with different light intensities,and the bending direction can be changed with different angles of incident light,which greatly improved the efficiency of light energy utilization.In addition,a series of research results shows,it can be greatly enhanced of the interface bonding strength between the PDMS layer and the GO layer due to the introduction of porous structure,and at the same time,it had a significant effect on the bending amplitude and improved response speed of film.