Modified melamine resins for optical applications

• Published in: Optical materials Vol. 12; no. 2; pp. 363 - 368
• Main Authors: Mahler, Joachim, Rafler, Gerald
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.06.1999; Elsevier Science
• Subjects: Applied sciences; Cyanuric chloride; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Melamine resin; Optical materials; Optics; Organic polymers; Physicochemistry of polymers; Physics; Polymers and organics; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; Second-order nonlinear optics; Cyanuric chloride; Second-order nonlinear optics; Melamine resin; Second order; Condensation polymerization; Experimental study; Lateral group; Hydrogen 1; Optical properties; Chemical preparation; Ultraviolet visible spectrum; Optical materials; NMR spectra; Absorption spectra; Polymers; Nonlinear optics; Mass spectra; Carbon 13; Modified material
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/S0925-3467(99)00037-3

A new four-step synthetic-route for combining chromophores with melamine resins was developed and their use for optical applications was demonstrated. Despite other melamine resins, the basic molecule of this system 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 precondensates. For increasing the stability and the solubility of these precondensates, the reactive methylolgroups were etherificated with methyl or butyl alcohol. One example of such a crosslinkable melamine-chromophore was illustrated and characterized by NMR- and mass-spectroscopy. The mass-spectrum gives evidence that the modified melamine precondensates are monomers and not a mixture of different oligomers like else in melamine-aldehyde prepolymers. The result of these systems is a crosslinkable melamine-chromophore monomer which is converted in a resin by thermal treating or by acids. It is remarkable that these polymers show an excellent thermal stability with a de-composition temperature beyond 300°C, a great advantage for using them as optical materials. Their usability as second-order nonlinear optical material was investigated by corona poling.