Multifunctional photochromic spiropyran dendrimers and their relaxation behaviors of photochromism

First and second generation dendrimers that exhibit unique photochromic behavior were synthesized through multi-step reactions. Their photochromic behavior under illumination of monochromatic ultraviolet light (λ = 365 nm) was investigated. The colorless dendritic dye solution and its film exhibit typical ring opening and E/Z geometrical transformation from spiropyran to merocyanine. The stability of photochromism in the two dendrimers was much better than that observed in the dye-attached polymer or dye-doped polymer system. Particularly, blend material system of photochromic dendrimer and photocrosslinkable dendrimer showed much better stability of the photochromism.