No abstract

Poly-o-acyloxyamides (PORAs) derived from a poly(ortho-hydroxyamide) from the 2,2'-Bis(3-amino-4-hydroxyphenyl) hexafluoropropane (APAF) diamine, APAF-POHA, have been synthesized and evaluated as gas separation materials. These polymers were made from poly(o-hydroxyamides) by derivatization of the free OH group with an aliphatic acid dichloride or dianhydride that allowed the introduction of acetyl or pivaloyl groups on their structure. All of them showed low-medium thermal stability due to a degradation of the amide moieties and most of them (those synthesized from isophthaloyl dichloride (IPC), 2,2'-bis(4-carboxyphenyl) hexafluoropropane dichloride (6FC) and 4,4'-dicarboxydiphenylsulfone dichloride (DPSC)) showed good mechanical properties.These poly-o-acyloxyamides have shown good permselectivities for He/N 2 and He/CH 4 separations and very good permeability-selectivity balance for the He/CO 2 separation.The acetyl PORAs showed better permeability versus selectivity balance than the pivaloyl ones. Moreover, selectivity increased while permeability decreased in the sequence: 6F-APAF -> IP-APAF -> DPS-APAF Intersegmental distances, d-spacing values, were shown to decrease along this sequence obtaining a nice correlation between permeability and d-spacing.