Preparation Of Waterborne Photosensitive Printing Electronic Materials And Its Application In Inkjet Printing

With the explosive development of electronic industry and materials science, printingelectronics is becoming the key technology of enabling low-cost, large-area, flexibleelectronics or photoelectric patterns. Therefore, the printing electronic materials andcorresponding printing techniques have inspired great interest among academic and industrialcommunity. Undoubtedly, the research reach a new climax after the emergence of some novelprinting electronic materials, such as carbon nanotubes (CNTs) and poly(3,4-ethylenedioxythiophene)(PEDOT). Dispersibility of CNTs and PEDOT is a prerequisitebefore their application in printing electronics. Even though aqueous dispersion is morefascinating from environmental perspective, materials obtained in aqueous dispersion directlyhave some intrinsic drawbacks, such as weak water-resistance and instability due to their highhydrophilic.In order to optimize the properties and performances of printing electronic materials, awater-soluble and photosensitive polymer P(SS-co-AA-g-GMA)(PSAG) was designed andreported in this thesis. Moreover, two kinds of printing electronic materials, i.e., PSAG-CNTsand PEDOT:PSAG was prepared from PSAG, with correspondingly devices, i.e.,MCNTs/paper gas sensors and transparent, flexible PEDOT conductive patterns also beingdeveloped with the assist of an ordinary piezoelectric inkjet printer. Finally, the effect ofphotosensitive property on functional coating was studied. The main contents and results areas follows:(1) Dispersion and performance of CNTs based on a novel water-soluble and photosensitivepolymer PSAGAcrylic acid (AA), sodium4-styrenesulfonate (SS), glycidyl methacrylate (GMA) wereused as monomers to synthesize water-soluble and photosensitive polymer-P(SS-co-AA-g-GMA)(PSAG). The structure and photosensitive property of PSAG were confirmed by1H-NMR. PSAG was found to be highly effective for the solubilization of CNTs in water,resulting in homogeneous and stable PSAG-CNTs aqueous dispersion. In addition, comparedto two common polymeric dispersants of Triton X-100and PSS, PSAG demonstrated betterperformance for dispersing CNTs at the same condition. Furthermore, a flexible crosslinkedPSAG-CNTs films with high electrical conductivity were formed after UV irradiation,followed by substrate conversion, endowing the CNTs films with better water-resistance.(2) MCNTs/paper chemical vapours sensors prepared by inkjet printingNew multiwalled carbon nanotubes (MCNTs) with a diameter of less than8nm and alength of0.2-5μm were used to obtain a water-soluble photosensitive MCNTs ink based onthe excellent dispersing performance of PSAG to CNTs. MCNTs chemical vapours sensorswere prepared by inkjet printing, using photopapers as substrates. The sensing results of theprinted MCNTs/paper sensors for chemical vapours showed that the sensors had betterresponsibility to common organic solvents, especially to ammonia and methanol, comparedwith ordinary sensors obtained by drop coating on gold electrodes. Additionally, the gas- sensing mechanism was discussed and the sensing results were depended on the relativequantity of MCNTs and PSAG, which played a role of antagonism.(3) Inkjet printing of PEDOT:PSAG for electronics fabricationPEDOT:PSAG conductive dispersion with outstanding printing performance wasobtained through the polymerization of EDOT with PSAG as dopant and polymeric template.In the condition of the appropriate surface tension, various conductive PEDOT:PSAG patternswere printed using photopapers and PET films as substrates with the help of an ordinarypiezoelectric inkjet printer. It showed that the conductive patterns on PET were flexible andtransparent. Additionally, the electrical conductivity and flexibility of the patterns printed onPET was superior to that of paper after comparing the performance of the devices on differentsubstrates and printing layers. Eventually, a crosslinked photosensitive PEDOT:PSAG gottenfrom UV irradiation demonstrated a great improvement in the water resistance and PETadhesion, while electrical conductivity decreased slightly and flexibility stabilized during thethis process.