Yuichi Makita

Nanoparticle chemisorption printing technique for conductive silver patterning with submicron resolution

Silver nanocolloid, a dense suspension of ligand-encapsulated silver nanoparticles, is an important material for printing-based device production technologies. However, printed conductive patterns of sufficiently high quality and resolution for industrial products have not yet been achieved, as the use of conventional printing techniques is severely limiting. Here we report a printing technique to manufacture ultrafine conductive patterns utilizing the exclusive chemisorption phenomenon of weakly encapsulated silver nanoparticles on a photoactivated surface. The process includes masked irradiation of vacuum ultraviolet light on an amorphous perfluorinated polymer layer to photoactivate the surface with pendant carboxylate groups, and subsequent coating of alkylamine-encapsulated silver nanocolloids, which causes amine–carboxylate conversion to trigger the spontaneous formation of a self-fused solid silver layer. The technique can produce silver patterns of submicron fineness adhered strongly to substrates, thus enabling manufacture of flexible transparent conductive sheets. This printing technique could replace conventional vacuum- and photolithography-based device processing.

Electrochemical elucidation of structural changes in physical organo bicontinuous microemulsion gel systems.

The structural changes in a bicontinuous microemulsion gel system in a sol-gel state were elucidated via determination of the apparent diffusion coefficients, which were estimated electrochemically. The temperature dependence of D(app) in the micro oil phase or the saline phase revealed complementary hysteresis, which occurred as a result of formation of a gel network and subsequent mesoscopic phase separation.