A catalyst don’t appear in the overall stoichiometry of the reaction it catalyzes, but it must appear in at least one of the elementary reactions in the mechanism for the catalyzed reaction. 6825-20-3, Name is 3,6-Dibromo-9H-carbazole, molecular formula is C12H7Br2N. In an article, author is Li, Xiuting,once mentioned of 6825-20-3, Safety of 3,6-Dibromo-9H-carbazole.
Novel high-performance poly(benzoxazole-co-imide) resins with low dielectric constants and superior thermal stabilities derived from thermal rearrangement of ortho-hydroxy polyimide oligomers
Unsatisfied dielectric property and insufficient thermal stability are major obstacles for the commercialization of polyimide resins in the future ultralarge scale integration (ULSI) or radar-wave-transparent composite applications. The incorporation of ortho-hydroxy diamine into a common phenylethynyl terminated oligoimides, aiming to subsequently form additional rigid benzoxazole units by the thermal rearrangement (TR), were prepared. The effects of TR-able codiamine on the processing ability of oligoimides, molecular packing and properties, including thermal stability, dielectric property and bonding ability to reinforcing fibers, for the resulting poly(imide-co-benzoxazole) (PI-co-PBOs) resins have been examined in detail. These thermally rearranged PI-co-PBO resins exhibit reduced dielectric constants of 2.56-3.4 at f = 0.1 GHz, lower than the cured PI with a dielectric constant of 3.55. Meanwhile, the 5 wt% weight loss temperature (T-d5) of the resultant resins increases from 455 degrees C for the cured PI to 491 degrees C for the PI-co-PBO-60 containing 60 mol% benzoxazole unit, and correspondingly, the tensile modulus of PI-co-PBO-60 reaches 2.47 GPa, which is 76% higher than that of the cured PI. These resultant PI-co-PBOs exhibit the combined excellent properties, indicating them a great potentials as the new low-dielectric constant polymer resins in microelectronic industries or advanced composites.
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Reference:
Benzoxazole – Wikipedia,
,Benzoxazole | C7H5NO – PubChem