August 7, 2014 12:00 am JST

New water-retaining gel raises hope for wide use

TAKASHI KUROKAWA, Nikkei staff writer

This slab of water can be made by stirring two ingredients together, then letting the mixture sit for several hours. © Courtesy of Nissan Chemical Industries

TOKYO -- Water just got stickier. Nissan Chemical Industries and Takuzo Aida, the deputy director of the Riken Center for Emergent Matter Science, have developed an easy-as-cake gel that can retain a huge volume of water.

     The gel has only two ingredients, both of which are themselves more than 90% water. The gel is capable of holding 15 times more water than both of its two components would otherwise be able to hold. The developers think the gel will have applications in a wide range of industries, including agriculture, civil engineering, construction and cosmetics.

     The two ingredients, let's call them solutions, are mostly water, but the gel can absorb even more water. It won't dissolve until heated to 120 C. This means any bacteria that grow in the gel can be destroyed with heat. In a dry climate, the gel can lose some of its water but will return to its original state when more water is added.

     One of the solutions is an organic macromolecule derived from a petroleum substance. The other is a water solution of fine particles made from a commercially available inorganic material. The developers say neither contains harmful substances.

     When the two solutions are mixed, an electric force bonds the organic and inorganic materials, enabling them to form a mesh structure. The volume doesn't change because the two materials only bond with each other. No chemical reaction occurs, and no harmful substance is produced.

     Making the gel is simple. Just stir the same volume of the two solutions together for a minute. The mixture will start to solidify at room temperature; the whole process is completed in several hours. Since the gel can be made into any shape, it can be made to fit any container's form factor.

     Today's water-retaining gels require multiple processes and special raw materials; they can only be produced in laboratories or factories. The new gel can be made pretty much by anyone anywhere.

     The developers expect that they can adjust the gel's mechanical strength and water-retaining levels by refining the substances in each solution. Hoping that the gel will be used for various industrial purposes, Nissan Chemical Industries has started providing samples of it.