Abstract
Since the discovery of carbon nanotubes (CNTs) in 1991, there had been a huge number of investigations on its basic properties and applications. Superior properties have been found such as high electric and thermal conductivity, mechanical strength, low threshold voltage for field emission, among many others. Nowadays, CNT/polymer composite gains much attention due to its industrial development especially for flexible electronics. The general access to CNT/polymer composite has been studied such as melt-mixing, spinning, in-situ polymerization and adhesive. Among these, the unavoidable problem was that the poor adhesion between CNT/polymer or the thermal deformation of substrate. On the other hand, microwave is a kind of specific energy that could transfer energy directly to materials via molecular interactions. The unique characteristics of microwave heating such as remotely, quickly, volumetric and material-selective make it much suitable for solving the adhesion problem of CNT/polymer.In this study, we first successfully examined the microwave heating of multi-wall carbon nanotube (MWNT) while the maximum temperature could be higher than 900 oC and made clear the heating mechanism. By such characteristic, MWNT can be easily bonded onto polymer substrates under microwave irradiation within a few seconds which we developed and called it microwave welding process. It was shown that the MWNTs are good ‘solders’ of polymer parts with a strength two orders of magnitude higher than those bonded by adhesives.The other study was focused on the implication of microwave welding. The microwave welding is a new access to flexible electronic companying with the paste-printing technique. There is no more interlayer such epoxy necessary in MWNT/polymer composite and the MWNT welded on polymer’s surface could fully exhibit its superior properties such electron conduction, field-emission. The flexible device would exhibit better than traditional way due to the strong surface welding without crack or deformation within polymer substrates. Finally, for more rapidly, uniformly and selectively heating characteristics, microwave welding was demonstrated to be of great importance in flexible electronics, such as conductors, resistors and field emitters.