Development And Device Application Of Nanomaterial Composite Photoresins Based On Two-Photon Polymerization

Three-dimensional(3D)intelligent integrated systems have the ability to sense the environment,analyze and store information,and respond to their surroundings accordingly.The realization of 3D intelligent integrated systems requires stimulus-responsive materials that can sense and respond to the surrounding environment,conductive materials that can transmit information,and semiconductor materials needed for computation and storage,which are difficult to achieve by traditional approaches of manufacturing.Femtosecond laser micro/nano 3D printing technology based on two-photon polymerization(TPP)is promising for realizing 3D intelligent integrated systems due to its high spatial resolution and true 3D fabrication capability.However,commercial photoresins suitable for TPP can only produce static 3D micro/nano polymer structures without stimulus-responsiveness,conductivity,and semiconducting functionality,which seriously constrain the development of 3D intelligent integrated systems.In this thesis,three functional nanomaterial composite photoresins suitable for TPP were developed to address the challenges above towards realization of 3D intelligent integrated systems.Functional 3D micro/nanostructures and their 3D micro/nanodevices with stimulus-response properties,conductive properties,and semiconductor properties were successfully fabricated.The development of new nanomaterial composite photoresins opens the way for TPP technology to realize 3D intelligent integrated systems.The main research contents and innovation points are as follows:(1)In 3D micro/nano manufacturing of stimulus-responsive materials,the polymerization mechanism of temperature-responsive hydrogel poly(Nisopropylacrylamide)(PNIPAM)was investigated in-depth,and a two-step freezing method was proposed to reduce the preparation time from 10 hours or several days to 2 hours.The prepared hydrogel had the following three advantages,including fast swelling/deswelling responsiveness,large swelling ratio,and excellent fatigue resistance under large strain.Furthermore,PNIPAM hydrogels were endowed with excellent photothermal response performance,fast near-infrared light responsiveness,and programmable deformability through the incorporation of multi-walled carbon nanotubes(MWCNTs).Finally,a photo responsive composite hydrogel photoresins was developed using PNIPAM hydrogel and MWCNTs,and a light-driven 3D micro-actuator was successfully constructed by TPP technology,which has fast response characteristics and spatial programmable deformation capability under near-infrared light.(2)In 3D micro/nano manufacturing of conductive materials,a conductive composite hydrogel photoresin was developed using acrylamide(AAm),polyethylene glycol diacrylate(PEGDA),and polyethylene glycol(PEG)-modified MWCNT(PEG-MWCNT).3D nanostructured electrically conductive hydrogels(NECH)were prepared though TPP technology and subsequent self-assembly of the conductive polymer poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate(PEDOT: PSS).In addition,microscale alcohol sensors and supercapacitors have been successfully fabricated using NECH,laying the foundation for the development of 3D integrated electronic devices.(3)In 3D micro/nano manufacturing of semiconductor materials,a semiconducting composite photoresin was developed using metal-organic framework(MOF)materials and photoresin monomers such as acrylates,epoxy resins,and hydrogels.3D architected metal oxides were produced by two-photon polymerization of semiconducting composite photoresins followed by high-temperature pyrolysis in oxygen,which possess high spatial resolution(170 nm),high shape fidelity,and high surface quality.In addition,3D microscale UV detectors based on Zn O were fabricated and characterized,demonstrating a large on/off ratio and high cycling stability.In this thesis,three different types of functional nanomaterial composite photoresins are developed for 3D intelligent integrated systems,and functional 3D micro/nano structures with stimulus responsiveness,conductivity,and semiconducting properties are fabricated using TPP micro/nano 3D printing.It aims to realize 3D on-chip intelligent integrated systems combining 3D structures with different functional properties,which is expected to play an important role in the fields of flexible electronics,biomedical electronics,photonics,and micro/nano electromechanical system.