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Synthesis of Aromatic Conjugated Main Chain Azobenzene Polymers and Their Properties
(2019) Bilen, Zeynep; Budak, Erhan; Bayazit, Mustafa Kemal; Özarslan, Özdemir
Azobenzene polymers have great potential and impact on fundamental and applied research. Howeverlittle is known about their thermal stability and degradation behavior. Herein, nine conjugated mainchain azobenzene polymers were synthesized using the nitroamine derivatives of some diphenylenecompounds such as 4-amino-4?-nitrobiphenyl 1, 4-amino-4?-nitrobiphenyl ether 2 and 4-amino-4?-nitrobiphenyl sulfide 3, and comonomers triphenylamine A, N-methyldiphenyl amine B andtriphenylphosphine C via a diazo coupling reaction. These heteroatom-containing polymers werecharacterized by 1H- and 31P-NMR, FTIR, UV–Vis and Raman spectroscopy. The thermal stability anddegradation behavior of these polymers were studied by means of TGA technique. Electronic spectra ofthe polymers recorded in DMF showed two strong maxima at ca. 280 and 380 nm. They were resistantto heat up to 270 °C and, produced 41-61% char under a nitrogen atmosphere at 800 °C. UL 94 burningtests performed for TPU Ravathane® (TPE-U) with added azobenzene polymer revealed that thesepolymers could be used as an intumescent reactive flame retardant additive, particularly forpolyurethanes and elastomers, due to their high char yield at relatively high temperatures (e.g 800 °C).The carbonized materials were further characterized by XRD and SEM/EDX.