Syntheses and properties of hyperbranched polybenzoxazole by thermal cyclodehydration of hyperbranched poly[<i>o</i>‐(<i>t</i>‐butoxycarbonyl)amide] via A₂ + B₃ approach

Abstract

Abstract The syntheses and properties of hyperbranched poly( o ‐hydroxyamide) [poly(HAB‐BCC)‐ABP], poly[ o ‐( t ‐butoxycarbonyl)amide] [poly(HAB‐BCC)‐ABP‐ t ‐BOC], and polybenzoxazole [poly(HAB‐cycloBCC)] were examined. Poly(HAB‐BCC)‐ABP was obtained from the polycondensation reaction of 3,3‐dihydroxy‐4,4′‐diaminobiphenyl (HAB) as an A 2 ‐monomer and 1,3,5‐benzenetricarboxylchloride (BCC) as a B 3 ‐monomer with 2‐amino‐4‐ t ‐butylphenol (ABP) in NMP in the presence of pyridine for 24 h. The reaction of poly(HAB‐BCC)‐ABP and di‐ t ‐buthylcarbonate (DiBOC) was performed to obtain the corresponding poly(HAB‐BCC)‐ABP‐ t ‐BOC with pendant t ‐BOC groups. The thermal cyclodehydration of poly(HAB‐BCC)‐ABP‐ t ‐BOC was carried out in the film sate at 400 °C, affording the poly(HAB‐cyclo‐BCC) in quantitative yield. Furthermore, the solubilities and thermal properties of these polymers were examined. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3640–3649, 2006