25717543751500Suitable diagram or picture showing the test set-up.
Schematic of processing in the segmented ﬂow tubular reactor (SFTR) system for the multi-gram synthesis of AgNPs.
Specific test method including the testing procedure
Two specific test methods that need to be used:
(i) The continuous production of silver nanoparticles (AgNPs)
(ii) The measurement of reaction yield by X-ray absorption near-edge spectroscopy (XANES).
The SFTR is consists of a micromixer that ensures that the reactants are efficiently mixed, a segmenter, and a PTFE tubular reactor placed in a thermostatic bath.
The continuous polyol synthesis of AgNPs in grams amount and in the size range of 7–104 nm was carried out in the segmented flow tubular reactor (SFTR).
Particle size can be tailored by controlling the synthesis parameters such as temperature, reactant concentrations, and polyvinylpyrrolidone (PVP) molecular weight.
The continuous production was tested for 4 h.
Reliable continuous production of AgNPs can be achieved with a lab-scale SFTR.
The produced particles were fully characterized with respect to size, size distribution, and chemical purity.
Futhermore the synchrotron-radiation high-resolution X-ray diffraction, and X-ray absorption spectroscopy data can be collected directly on the AgNPs suspension.
In particular, from XANES experiments, the conversion yield of Ag+ to Ag0 will be measured.
The results should be consistent with a two-step process where PVP controls the particle nucleation while growth is ensured by thermally induced ethylene glycol oxidation.
In conclusion, silver is one of the most desired materials widely used in conductive inks. The present conductive ink applications in printed electronics have a very bright market. Researchers are focusing on silver ink due to its eﬀective properties compared to other materials such as copper. Conductive ink patterns can be utilized in flexible electronics and optoelectronics applications. Silver has been considered to be a better pigment material in conductive inks due to its high electrical and thermal properties. However, there are several challenges for synthesis of AgNPs. Firstly, how to get the eﬀective size reduction. The size of the resultant particles plays a crucial role in the nanoparticles synthesis. Silver conductive ink synthesis primarily depends on the size of the particles due to its application in printed electronics and inkjet printing. Next the limitations is how to find the ways to avoid oxidation. Oxidation is a very serious and undesired issue that has become a main drawback in a few metal-based inks. Oxidation occurs when the surface of the metal exposed to air reacts with the oxygen in the atmosphere and forms a dense layer of metal oxide. In order to overcome the oxidation of metal atoms, ink printing has to be carried out in an inert atmosphere or vacuum, or the ink has to be stabilized by adding suitable blends or stabilizers that restrict oxidation and enhance conductivity.
Besides that, agglomeration is one of the major consequences in nanoparticle synthesis. It aﬀects the life and performance of the application and the applicant. As AgNPs are widely used in inkjet printing and in conductive ink pens, the agglomerations block the dispenser system. For example, the nozzle of the ink jet printer cartridge or the nib of the conductive ink pen. Hence, it results in blockage and malfunction of the equipment. This agglomeration can be over-come by adding suitable capping agents. Electrically conductive adhesive (ECA) has made considerable advances in recent years. Compared to metal solder, ECAs offers numerous advantages, such as environmental friendliness that can eliminate the lead usage and flux, mild processing conditions, fewer processing steps that can reduce processing cost, low stress on the substrates and fine pitch capability. However, ECAs have some challenging issues, such as lower electrical and thermal conductivities compared to solder joints, conductivity fatigue in reliability tests, limited current carrying capability, poor impact performance and etc that need to be upgrade in order to have a better result.