Converting waste expanded polystyrene into polymeric azo dyes containing the sulfonamide group

Using waste expanded polystyrene as raw materials, a series of polymeric azo dyes containing the sulfonamide group were prepared by chlorosulfonation, amidation, hydrolysis, diazotization and coupling reactions in this study. The main influence factors of each step reaction were discussed and the proper reaction conditions were obtained. The polymeric azo dyes prepared showed good thermal stabilities, and their 5 % weight loss temperatures were all higher than 350 °C. These polymeric dyes could solve in toluene at the room temperature. They showed different maximum absorption wavelengths in the ultraviolet–visible region and gave various colors. The relationships between colors and molecular structures of polymeric dyes were investigated. These polymeric azo dyes prepared have potential applications in dyeing polymer materials, such as plastic and fiber.