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Dí,ez, Blanca,Cuadrado, Purificació,n,Marcos-Ferná,ndez, Á,ngel,de la Campa, José,G.,Tena, Alberto,Prá,danos, Pedro,Palacio, Laura,Lee, Young Moo,Alvarez, Cristina Elsevier 2018 Reactive & functional polymers Vol.127 No.-
<P><B>Abstract</B></P> <P>Two series of aromatic poly(<I>ortho</I>-hydroxyamide)s (poly(<I>o</I>-hydroxyamide)s, HPAs) were prepared by reaction of two diamines, 2,2-bis(3-amino-4-hydroxyphenyl) propane (APA) and 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (APAF), with four aromatic diacid chlorides; terephthaloyl dichloride (TPC), isophthaloyl dichloride (IPC), 2,2-bis[4-chlorocarbonylphenyl)hexafluoropropane (6FC) and 4,4′-sulfonyldibenzoyl dichloride (DBSC). Amorphous HPAs with high molecular weights (inherent viscosities higher than 0.5 dL/g) and relatively high glass transition temperatures (220–280 °C) were obtained. Dense membranes of HPAs were able to undergo a thermal rearrangement (TR) process to polybenzoxazoles (β-TR-PBOs) heating at moderate temperatures (between 250 and 375 °C), and their complete conversion was reached at a temperature below 375 °C, depending on the <I>o</I>-hydroxy diamine moiety, APA and APAF. The β-TR-PBOs films derived from APAF showed a higher thermal stability and higher Tg than those from APA. Gas separation properties of TR-PBOs membranes were superior to those of their poly(<I>o</I>-hydroxyamide) precursors, particularly for the following gas pairs: O<SUB>2</SUB>/N<SUB>2</SUB>, CO<SUB>2</SUB>/CH<SUB>4</SUB>, He/CH<SUB>4</SUB> and He/CO<SUB>2</SUB>.</P>