Reversibly Photocoloring System Containing Diazonium Salt

Abstract

In a system consisting of diphenylamine type diazonium salt, coupler and matrix polymer, two different colored products were formed by an ammonium development or irradiation of. UV ray one was an orange colored species formed by the usual coupling reaction and the other was a greenish blue species produced photochemically.
In ammonia gas bath, the diazonium salt (P-diazodiphenylamine fluoroborate) and the coupler (m-hydroxydiphenylamine) in a polymer matrix were coupled to form an orange azo dye. On the irradiation of UV ray, the orange product turned to the greenish blue one. This color change took place reversibly by the two treatments.