Methods to control the dispersion stability of multicomponent slurry, in which multiple species of particles were dispersed into the solvent, and to grant external stimuli‒responsive properties to the slurries by the addition of small amounts of organic additives will be introduced. The design of polyethyleneimine partially complexed with fatty acids was useful to control the stability and the particle assembled structure of multicomponent slurries. The addition of small amounts of multifunctional acrylates to this slurry resulted in photo‒ and heat‒responsive slurries. Some demonstrations for three-dimensional structuring of ceramic materials using the designed stimuli‒responsive slurries will be further explained.
The surface profile of automotive topcoats, which affects the appearance such as orange peel and gloss, is determined by two mechanisms.
The surface irregularity with wavelength of about 1-5 mm is formed on the paint film during spraying, since the volume of paint droplets deposited on the substrate is not uniform along the substrate surface. Though the irregularity is reduced during drying and baking, it does not disappear, resulting in the unevenness like orange peel.
The irregularities of substrate surface, interface between wet film layers by wet-on-wet processing, and pigment distribution in the films are transcribed on the surface of top layer (clearcoat in many cases), resulting in the unevennesses with various wavelengths, after the top layer cannot flow along the substrate surface. It is because the irregularities make the shrinkage of the film thickness ununiform along the substrate surface.
Drying of suspensions has been widely used in industrial processes. Involatile components are concentrated during evaporation of solvents, which induces precipitation of solutes or packing of suspended particles. Evaporation also causes deformation of liquid-air or liquid-liquid interfaces and flows in drying liquid films. They are correlated to others in a complicated manner and fundamental understanding is still necessary. In this manuscript, we provide a short review on recent studies on drying-induced phenomena, especially on drying suspensions.
The presence of flexible circuits in wearable electronics, especially medical devices, has been expanding. The thick film printing process has been becoming the key technology in this area. Advantages and disadvantages of the technology were evaluated comparing with traditional photolithography and etching process. The thick film printing process is able to generate functional circuits employing new unique materials. Several examples were introduced to show the mechanisms of the printed devices.