Thermally rearranged polybenzoxazoles membranes with biphenyl moieties: Monomer isomeric effect

Gas separation membranes made through thermal rearrangement of ortho-methoxypolyimides

“…For the other treatments, a rather linear change was observed. Accordingly, the use of thermal treatment led to lower chain packing densities, which was in agreement with other TR polymers previously reported [30,34,36]. Table 2.…”

“…According to previous studies [30,34,35] the thermal cyclization reaction is very sensitive to the applied temperature, showing an acceleration in the thermal rearrangement kinetics on increasing temperature.…”

Effect of methanol treatment on gas sorption and transport behavior of intrinsically microporous polyimide membranes incorporating Tröger׳s base

“…All of the chemicals listed above except for the dianhydrides were used without further purification. Both dianhydrides, 6FDA and BTDA, were purified by sublimation before use [38].…”

“…Therefore, methanol treatment could help improve the plasticization resistance in PI-TB-1-M membranes. The plasticization resistance of the PI-TB membranes is comparable to that of thermally rearranged (TR) polymers, which demonstrates outstanding gas transport properties with the potential for large-scale application [16,38]. Sanders et al reported that TR450 prepared from HAB-6FDA-based polyimide exhibited no plasticization behavior for CO 2 feed pressures of up to 16 atm [69].…”

Thermally rearranged polybenzoxazoles and poly(benzoxazole-co-imide)s from ortho-hydroxyamine monomers for high performance gas separation membranes

“…Aromatic dihydroxydiamines (2HDA), 2,2′-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (APAF), 3,3′-dihydroxybenzidine (pHAB), and its isomer 3,3′-diamino-4,4′-dihydroxybiphenyl (mHAB) have been used for these purposes [16][17][18][19][20]. APAF is quite expensive; much more so than pHAB, while mHAB is a non-commercial reagent that was recently reported to be a suitable raw material for TR polymers [20]. All three 2HDAs have proven to be good nucleophiles and present a reasonably high reactivity against the dianhydride 6FDA, although the diamine APAF is comparatively less reactive because of the electron withdrawing effect of its hexafluoroisopropylidene group.…”