Phase-separation process in polymer mixtures: For the first time, 3D digital images of phase-separating binary polymer mixtures were constructed with nearly equal phase volumes and nearly equal molecular weights. The images were found to be bicontinuous, and to have characteristics of a "sponge-like" structure found for microemulsions. This research has contributed to the field of critical phenomena: the sponge-like structure was proven to be a real-space structure for phase-separating binary mixtures of simple liquids.
Organization of block copolymers: A high-resolution small-angle-X-ray scattering analysis was applied to explore the order-disorder transition.
(ODT) of block copolymers using a specially constructed Bonse-Hart type apparatus (USAXS). The analysis led to the discovery of a biphase region, where ordered and disordered phases coexist at thermal equilibrium around the ODT temperature.
Phase behavior of colloidal dispersions: Aqueous dispersions of ionic colloidal particles were investigated from the viewpoint of phase transitions and the self-organization of supermolecules. The ordered, disordered, order-disorder coexistence, and gas-liquid coexistence phases were found in the space determined by the salt concentration, particle charge density and particle concentration.
Internal structure of polymer gels: A chemical gel is a cross-linked three-dimensional polymer network swollen by a fluid. An intriguing hierarchy structure which developed in a macroscopically homogeneous poly (N-isopropylacrylamide) gel prepared via a chemical reaction was clarified. It visualized for the first time a sponge-like structure comprising both network-rich and network-poor phases with an average spacing of ca. 10 mm.
Nano-processing method developed: Novel nano-scale structures were developed utilizing the microphase separation of block copolymers. A method was developed to selectively degrade one of the microdomains to create unique materials containing regularly spaced networks of holes. These holes were further plated with metals to produce polymer/metal hybrids. Hybrid structures were also developed by introducing metal nanoparticles selectively into one of the nanodomains.