Graduate School of Science and Engineering Applied Chemistry

<1> Preparation and reaction mechanism of fine particles

We conduct basic studies on the precipitation process of fine particles where molecules aggregate in solution by transport phenomena (diffusion, flow, etc.), and finally become particles through clusters or nuclei (phase transition). We consider to not only the solute concentration or the solution temperature but also the reaction field itself and external force field as parameters of the reaction mechanism. The micelles or reverse micelles which are the spontaneous association of surfactant in an aqueous solution or organic solvent, and the gel formed from polymers or clay particles are investigated as the reaction field during the preparation process of metal, ceramic, or polymer particles. We also examine the particle formation using the electric or ultrasonic fields as the external force field.

<2> Particle assembly for functional materials

Particle assemblies for functional materials are investigated using advective flow and external field such as electrostatic or vibrational fields. Monolayer ordered particle assembly of polystyrene latex (PSL) particles was formed on the glass plate using the continuous coating operation controlled by interaction forces among particles and between particles and a glass plate, as well as the operation conditions such as the advective flow rate, drawing speed of the plate, and feed rate of particle suspension. As the application of this assembly, we demonstrated to make the dots array prepared by gold nanoparticles, which we expect to apply the substrate for surface-enhanced Raman scattering. We also try to make the electrode of titania nanoparticles for dye-sensitized solar cell by using electrophoresis.

<2> Analysis and control of local interfacial transport properties in complex multiphase flow processes

We use "Visualization" and "Computational Fluid Dynamics (CFD) simulations" to analyze the complex dynamics engendered by interphase interaction. Specifically, we are creating methods to measure mass dispersion based on Laser-Induced Fluorescence (LIF) and ascertaining the state of mass dispersion around the interface using rapid/high-sensitivity fluorescent imaging with the aim of controlling the reaction based on quantification of the spatio-temporal distribution of concentration of the dissolved component as well as the local flow structure and concentration/dispersion pattern within the multiphase flow.

<3> Simulation of jet-induced gas mixing and combustion in reactors

We use "CFD simulations" to conduct numerical analysis of the flow, mixing and reaction of the mixing dispersion when multiple gases of different reactivity (e.g. high temperature/low temperature) are injected into the reactor, and we compute a design for the mixing process including the mixed-gas injection nozzle by different methods of introducing gasses and under different operating conditions. We also conduct cold model analysis using "flow visualization" to research the optimum design for the mixing process.

<4> Development of energy-saving separation process for volatile organic compounds using ultrasonic atomization

As opposed to universal separation processes such as those that use distillation columns, we are working on the development of an advanced separation process for organic solvents including alcohols and other amphiphatic compounds suitable for use in high-mix low-volume manufacturing (when there is limited facilities space, or short production lead time). More specifically, we are working on the production of "temperature-seal type single-pass ultrasonic atomizing separator" and conducting performance evaluation of this separator. In addition, we are looking at the separation and removal of various organic compounds using this atomization technology, with the aim of establishing this as one of environmental technologies.

<5> Evaluation of transport and fractionation of fine particles through microchannels

To control the basic properties (particle size, dispersion, etc) of fine particle transport required for aggregation of fine particles, we need to establish evaluation techniques including the distribution of the liquid phase flow rate, the fine particle pathways, and the interaction between fine particles to elucidate the properties of fine particle transport and fractionation that accompany pathway changes and curves. To this end, we use "CFD simulation" to analyze fluid and particle motion through microchannels, leading to guidelines for the design of microchannels. Based on this, we will produce a prototype, and use "longitudinal micro-PIV measurement techniques" to conduct "high-resolution, rapid visualization" analysis of fine particle transport and fractionation phenomena in the channel flow field.