Homopolymers of 3-Hydroxy-4-(m-methacrylamidophenylazo)- 2-naphthanilides and their Tautomerism

Abstract

Syntheses of homopolymers of Naphthol AS series azo dyes containing polymerizable group in diazo component and the relationship between tautomerism and light fastness of the dyes have been investigated. Homopolymers of 3-hydroxy-4- (m-methacrylamidophenylazo) -2-naphthanilides were prepared by the polymerization of monomeric dyes which in turn were synthesized by the coupling reaction of m-methacrylamidophenyldiazonium chloride with 3- hydroxy-2-naphthanilides. The aryl groups are C₆H₅, 3-NO₂C₆H₅, 2-CH₃C₆H₄, 2-CH₃0C₆H₅, 4-Cl0₆H₄, and β-C₁₀H₇.
It was proved from GPC analysis that the polymeric dyes consisted of dimerecamer, the main components being tetramerentamer. Their visible and infrared absorption spectra showed that a content of keto form in the polymeric dye was smaller than that in the monomeric dye.
Examination of light fastness of the dyes in poly (methyl methacrylate) film revealed that, while the ratio of keto/enol forms in the monomeric dye remained almost constant during fade, the content of keto form remarkably decreased with increasing fade in the polymeric dye. Therefore, poor light fastness of the polymeric dyes appeared to be due to partial interference in the tautomerization between keto and enol form by polymerization.