Modified melamines and melamine resins for E/Z-isomerization

A new four-step synthetic-route for combining azochromophores with melamine resins was developed and their potential for E/Z-isomerization were shown by Kelvin-probe technique. Despite of other melamine resins, the basis molecule of the synthesized melamine-chromophore and the resulting melamine-chromophore resins is the 2,4,6-trichloro-1,3,5-triazine, the cyanuric chloride. In the first step, the azochromophore was bonded to the s-triazine-ring. Then, the residual chlorines of this triazine-chromophore were substituted by ammonia or primary amines. In the third step, formaldehyde was added, leading to melamine-chromophore monomers. For increasing the stability and the solubility of these monomers the reactive methylolgroups were etherificated with methyl or butyl alcohol. The result of these systems is a crosslinkable melamine-chromophore monomer which is converted in a resin by thermal treating or by acids. An optically induced switching of two different melamine-chromophore monomers and the resins were monitored by measuring the surface, potential. It was done by Kelvin-probe technique. The results show a high surface potential difference between the cis- and the trans-state of the ate-group-systems, depending first on the attached chromophore and second whether the prepared films are monomer-layers or resins. (C) 1999 Elsevier Science S.A. All rights reserved.