Photochemically induced formation of adhesive hydrogels from sodium alginate, acrylamide, and iron sandwich complexes.

Visible light irradiation of an aqueous solution of sodium alginate and organometallic complex [(C 5 H 5 )Fe(toluene)]BF 4 transforms it into a rigid hydrogel due to crosslinking of the carboxylate groups by the iron ions. Irradiation of the same iron complex together with K 2 S 2 O 8 initiates the polymerization of acrylamide, which provides an efficient method for light-controlled one-step preparation of alginate-polyacrylamide double network hydrogels, which are capable of gluing wet glass with 100-200 kPa shear strength.