Aromatic poly(benzoxazole)s from multiring diacids containing (phenylenedioxy)diphenylene or (naphthalenedioxy)diphenylene groups: Synthesis and thermal properties

Abstract

Poly(arylether benzoxazole)s (PAEBOs) were prepared from a series of fully aromatic dicarboxylic acids containing (phenylenedioxy)diphenylene or (naphthalenedioxy) diphenylene groups and 3,3′‐dihydroxy‐4,4′‐diaminobiphenyl (I) or 4‐4′‐(hexafluoroisopropylidene)bis(2‐aminophenol) (II) through high‐temperature direct polycondensation. A phosphorous pentoxide/methanesulfonic acid mixture or trimethylsilylpolyphosphate was used as a condensing agent. All the PAEBOs were amorphous and soluble in strong acids, and those derived from II were also readily soluble in polar organic solvents. Flexible films were cast from their chloroform solutions. The PAEBOs showed inherent viscosity values of 0.68–2.06 dL/g (CH3SO3H, T = 30 °C, c = 0.15 g · dL−1). Thermal analysis indicated glass‐transition temperatures ranging from 236 to 270 °C and thermal stability (5% weight loss) in nitrogen up to 526 °C. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1172–1178, 2000

Synthesis and properties of novel cardo aromatic poly(ether‐benzoxazole)s

“…The first is a two‐step process that involves the initial formation of poly( o ‐hydroxy amide)s from bis( o ‐aminophenol)s or their silylated derivatives with aromatic diacid chlorides followed by thermal cyclodehydration to PBOs in solid state or in solution 7, 10, 21–24. The second is a one‐step route directly producing PBOs by the melt polycondensation of bis( o ‐aminophenol)s with aromatic diacid diphenyl esters25 and by the solution polycondensation with aromatic diacids,14, 26–29 poly(terephthalic acid anhydride),30 or 1,4‐bis(trichloromethyl)benzene31 in acidic media such as poly(phosphoric acid) and phosphorus pentoxide/methanesulfonic acid. Furthermore, another facile method has been reported for the preparation of PBOs, that is, the one‐step polycondensation method from nitrile‐bearing o ‐aminophenols32 and from monomer pairs of bis( o ‐aminophenol)s and dinitriles 33.…”

New poly(ether benzoxazole)s containing xanthene cardo groups

“…As a consequence, research on enhancing their processability and solubility has employed a variety of methods to chemically modify their structure, such as through the incorporation of flexible linkages into the PBO backbone 3 –6 or attachment of bulky side groups. 7 –10 Cardo groups such as 9,9-fluorenylidene, 1,1-cyclohexylidene, and 4,7-methanohexahydroindane-5,5-diyl could be considered as bulky groups and have been incorporated into the structure of PBOs to prepare high-performance polymers with a combination of enhanced thermal stability, high glass transition temperature ( T g ), and improved solubility. 11,12 In our previous studies, 13 –15 it has been demonstrated that introduction of both the ether linkage and cardo xanthene units into the polymer molecules results in the corresponding poly(ether ketone)s, polyamides, and polyimides with improved solubility that retain good thermal properties.…”

Novel Self-Dyed Wholly Aromatic Polyamide-Hydrazides Covalently Bonded with Azo Groups in Their Main Chains: 1. Structure-Property Relationships

“…Aromatic polyamide-hydrazides are well known as precursors to polyamide-1,3,4-oxadiazoles, which are one of the most important classes of chemically and thermally stable heterocyclic polymers [ 25 , 26 ]. It is well established that all aromatic polymers containing only benzoxazole [ 27 , 28 ] or 1,3,4-oxadiazole [ 29 , 30 ] moieties as the main structural feature of the polymer chains exhibit excellent thermal stability and other attractive physical properties.…”