Research Trends of Stimuli-Responsive Polymer Hydrogels in Japan

In recent years, biological functions have been increasingly investigated on the molecular and/or atomic level. Synthesis and assemblies of various functional polymers have also been researched. In particular, research of stimuli-responsive polymeric materials having the func tion and efficiency of a biological system has been of interest. The materials are still in the embryonic period, but there are great expectations surrounding their progress. In this article, the research trends in Japan of stimuli-responsive polymer gel are summarized from the viewpoint of synthesis, fabrication, and applications. On synthesis, researches have been summarized on stimuli including light, heat or temperature, pH or ion, electric field, and chemicals. On fabrication, researches have been summarized on two types of fabrication methods: chemical methods, such as grafting and hybridization; and physical methods, such as blend, microgel, film, fiber and composite. On industrial applications, many at tempts have been made in recent years concerning the released control of chemicals, especially drug delivery systems. Controls of adsorption, permeation, and enzyme reaction using stimuli-responsive polymer gels have also been attempted in the chemical engineering and bioengineering fields. On applications to actuators, the construction of some micro-actuating systems has been attempted. The stimuli-responsive polymer gels (chemomechanical gels) are very promising, both in the field of fundamental study and in the field of applied research.