Synthesis of and photodegradation in a series of poly(ethylene terephthalate)–co–4,4′-sulfonyldibenzoate yarns

Phototendering studies of poly(ethylene terephthalate) homopolymer yarn and a series of poly(ethylene terephthalate–co–4, 4′-sulfonyldibenzoate) copolymer yarns have shown that photosensitized degradation occurs more readily in the copolymers than in the homopolymer. A photo-oxidative mechanism involving the second monomer, dibutyl 4, 4′-sulfonyldibenzoate, has been proposed to account for the photosensitization. The photophysical processes in the second monomer, dibutyl 4, 4′-sulfonyldibenzoate, were studied by absorption and luminescence techniques. The lowest excited singlet and triplet in this compound were identified as the ¹(π, π^*) and ₃(π, π^*) states, respectively. The energy levels in the second monomer have been assigned as follows: ¹S₁ ～ 33,000 cm^?1, ¹S₂ ～ 42,000 cm^?1, and ³T₁ ～ 26,000 cm^?1.