Polybenzoxazoles and polybenzothiazoles

Abstract

Polybenzoxazoles of high molecular weight were prepared easily by the solution polycondensation of 3,3'-dihydroxybenzidine dihydrochloride or 3,3'-diamino-4,4'-dihydroxybiphenyl dihydrochloride with both aromatic and aliphatic dicarboxylic acids in polyphosphoric acid. Polybenzothiazoles were prepared from 3,3'-dimercaptobenzidine dihydrochloride and dicarboxylic acids by the same procedure.Aromatic polybenzoxazoles and polybenzothiazoles showed BR excellent thermal stability up to 450 "C. in air. They were insoluble in organic solvents. ZUSAMMENFASSUNG:Polybenzoxazole hohen Molekulargewichtes konnen leicht hergestellt werden durch Polykondensation von 3,3'-Dihydroxybenzidin-dihyclrochlorid oder 3,3'-Diamino-4,4'dihydroxybiphenyl-dihydrochlorid mit aromatischen und aliphatischen Dicarbonsauren in Polyphosphorslure. Polybenzothiazole lassen sich nach der gleichen Methode aus 3,3'-Dimercaptobenzidin-dihydrochlorid und Dicarbonsauren herstellen.Aromatische Polyhenzoxazole und Polybenzothiazole zeigen eine ausgezeichnete thermische Stabilitlt bis 450 "C in Luft. Die Polymeren sind unloslich in organischen Losungsmitteln.

Preparation of carbon alloy catalysts for polymer electrolyte fuel cells from nitrogen-containing rigid-rod polymers

“…Polyimides (PI), polyamides (PA) and azoles (Az) were prepared by the usual polycondensation methods [22][23][24][25][26], as shown in Fig. 1.…”

Synthesis of aromatic polybenzoxazoles by silylation method and their thermal and mechanical properties

“…[12,[17][18][19] The second is a one-step process directly producing PBOs that includes the melt polycondensation of bis(o-aminophenol)s with aromatic dicarboxylic acid diphenyl esters, [20] and the solution polycondensation with aromatic dicarboxylic acids in acidic media like polyphosphoric acid. [3,13,21,22] The present study has two main objectives. The first is to prepare films of various aromatic PBOs through the two-step silylation method [12,[17][18][19] by the polycondensation of trimethylsilyl-substituted bis(o-aminophenol)s with aromatic dicarboxylic acid chlorides affording precursor poly(o-trimethylsiloxy-amide)s, followed by thermal cyclocondensation (Scheme 1).…”

Facile synthesis of aromatic polybenzoxazoles from monomers havingo-aminophenol and nitrile functions

“…These thermal stability data were consistent with those of the aromatic PBOs already reported in the literature. 10,11,20 In conclusion, we have found that the aminophenolnitrile route or its hydrochloride process was a simple and facile method for the synthesis of aromatic PBOs having moderately high molecular weights, as well as for that of aliphatic PBOs reported previously, compared with other known synthetic methods. In addition, the aminophenol hydrochloride-nitrile process was more useful than the parent aminophenol-nitrile route for preparing aromatic PBOs with higher molecular weights.…”

“…These IR spectra were agreed quite well with those of the aromatic PBOs reported previously. 10,11,20 The thermal stability of the aromatic PBOs 3, 4, 8, and 9 was evaluated by means of TG at a heating rate of 20°C/min in nitrogen. As expected, the two all-aromatic PBOs 3 and 8 showed the best thermal stability in terms of temperatures for 10% weight loss, which were 695 and 665°C, respectively.…”