2,2′,6,6′-Tetrabromo-3,3′,5,5′-tetramethyl-4,4′-biphenol (TTB)–flame retardant copolycarbonates and copolyesters^†

2,2′,6,6′-Tetrabromo-3,3′,5,5′-tetramethyl-4,4′-biphenol (TTB) is a new flame retardant monomer possessing a high degree of chemical and thermal stability. This brominated biphenol can be directly incorporated as a comonomer in condensation polymerizations. An example is the preparation of copolycarbonates of TTB and 2,2-(4-hydroxyphenyl)propane (BPA) via the aqueous caustic phosgenation method. The reaction of TTB with either ethylene oxide or ethylene chlorohydrin affords 4,4′-bis(2-hydroxyethoxy)-2,2′,6,6′-tetrabromo-3,3′,5,5′-tetramethylbiphenyl (TTB-Diol). This diol is melt polymerized into a series of terephthalate copolymers with 1,4 butanediol. The above copolymers possess flame retardancy, thermal stability, and good mechanical properties. These high-bromine-content copolymers are blended with nonhalogen-containing polymers to afford blends with specific degrees of flame resistance.