In order to create a sustainable society, the recycling of polymeric materials is an extremely significantproblem to be solved. Polyurethanes are industrially important polymeric materials, and their recycling intoraw chemicals is extensively reported. In this review, the development of thermal and chemical recyclingmethodologies is described, with a focus on the novel chemical recycling of polyurethanes by hydrolysisreactions.Recently, we found a carbonic acid-catalysed hydrolytic system for polyurethanes. In this reaction,pressurised CO₂ is loaded into a mixture of polyurethane and water. The CO₂ dissolves in water to formcarbonic acid that functions as an acid catalyst for the hydrolysis. After the reaction is complete, CO₂ iseasily removed from the reaction system by venting the vessel. The hydrolysis reaction affords raw chemicals（diamine and alcohol） from polyurethanes in high yields with high purity and selectivity. The hydrolysisbehaviour is dependent on the chemical structure of the polyurethanes, and the reaction conditions such asthe CO₂ pressure.The reaction conditions in our system are relatively mild compared to those in a similar system in waterwithout CO₂. Moreover, strong-acid or strong-base catalysts are not required, thus removing the needto neutralise the reaction mixture and isolate the reaction products. CO₂ is abundant, cheap, minimallyhazardous, non-flammable, easily available, and easily removable. Therefore, this hydrolysis of polyurethanewith CO₂ is an environmentally friendly chemical-reaction-based method.

Various kinds of applications using water-soluble polymers were introduced in this review. pH-responsiveunimer micelles were prepared via conventional random copolymerization. The random copolymer formedunimer micelles at acidic condition, while it expanded at basic conditions due to electrostatic repulsion of thependant anions. Also pH-responsive diblock copolymers were prepared via controlled radical polymerization.The diblock copolymer dissolved as a unimer state in basic water, while it formed micelles in acidic conditions.To prepare inorganic metal oxide hollow nanoparticles, we used a water-soluble ABC type triblock copolymer.The polymer micelle formed from the triblock copolymers can be used as a template, which was decomposedby calcination to prepare inorganic hollow nanoparticles. Oppositely charged diblock copolymers containingwater-soluble nonionic block can form water-soluble polyion complex（ PIC） micelles and vesicles. Controlledradical polymerization is powerful tool to prepare new designed water-soluble polymers.

Improvement of adhesive strength of one-component moisture curable cyanoacrylate adhesive wasinvestigated. A relation between the adhesive strength and the color of the fracture surface which wasquantitatively measured by heating after moisture cure was examined with General structure steel, 400 as anadherend. The surface texture of adherend was made constant. The humidity during bonding and curing waskept constant.An effect of heating temperature and time on the adhesive strength was observed with single lap joint. Asa result, the adhesive strength exhibited to increase by heating after it had been cured at room temperature.However, heating above certain temperature would make the adhesive strength rather lower.In addition, the adhesive strength was turned out to be possible to estimate by observing surface color.

Surface treatment of silica particles with 3-glycidoxypropyltrimethoxysilane（ GPTMS） by dry-treatmentmethod was done and the characterization of treated layer by thermogravimetric（ TG） measurement wasinvestigated. For this purpose, the TG curves of treated silica and GPTMS oligomer were compared. The TGcurve of treated silica showed three-steps weight losses. The 1st-step decreased whereas the 2nd- and 3rdstepsincreased with the increase of stored days at room temperature after surface treatment. After the alcoholwashing, the TG curve became only 3rd-step and the quantity of 3rd-step decreased by washing. The oligomerwas prepared by heating of GPTMS/water mixture. After sufficient heating, the TG curve of oligomer showedonly 3rd-step. By comparing of TG curves for treated and oligomer, each step of TG curve for treated silicawas estimated as folloes: The 1st-step is the evaporation of monomeric GPTMS without any interaction withsurface. The 2nd-step is the physisorbed monomeric GPTMS formed hydrogen bonding with surface. The 3rdstepis the chemisorbed and physisorbed silane oligomer and chemisorbed monomeric GPTMS. It was foundthat the comparison of TG curves of treated particle before and after washing is useful for the characterizationand quantification of various adsorption states of silane on particle surface.