Advanced polyimide varnish for optical fiber coating fabrication

Abstract

Using one-step high-temperature polycondensation, soluble polyimide based on 9,9-bis-(4’-aminophenyl) fluorene and 3,3’, 4,4’-diphenyl oxide tetracarboxylic acid dianhydride is synthesized. Polyimide varnishes inN-methyl-2-pyrrolidone are prepared, and technological conditions of their deposition during fiber drawing are studied. A polymer coating thickness over 6 μm is achieved for a single application. It is demonstrated that the developed coating almost does not degrade for a long time at temperatures to 250 °C and completely protects the optical fiber surface from water penetration.