Sorption, diffusion, and permeability of humid gases and aging of thermally rearranged (TR) polymer membranes from a novel ortho-hydroxypolyimide

摘要: Abstract We studied in this work the properties of a new membrane (TR-PBO) obtained by solid state thermal rearrangement at 450 °C recently developed polyimide precursor, (mHAB-6FDA), which was synthesized reaction (3,3-diamino-4,4-dihydroxybiphenyl, mHAB) with 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA). The mHAB monomer is an isomer commercial 3,3′-dihydroxybenzidine (pHAB), used to form more popular precursor pHAB-6FDA. TR-PBO membranes from mHAB-6FDA showed excellent CO 2 permeability (720 Barrer) and good /CH 4 ideal selectivity 23. found out that enhances solubility diffusion coefficients 10 bar factors as high 1.3 5, respectively. Larger enhancements, however, were observed case CH , causing diffusivity decrease factor 2.6 ~1.5 upon rearrangement. pure gas modeled Dual Sorption Mode model NELF model. two models then predict mixed behavior terms solubility-selectivity, highlighting effects competition are consistent those other glassy polymers. also performed moisture sorption tests measurements presence humidity. It increases hydrophobicity and, consistently, mTR-PBO much stable humidity than membranes. Finally, effect aging on performance analyzed. A 30% TR polymer (around 50 µm thick) after 6 months, while increased 20%. These results indicate that, even outstanding close Robeson's upper bound.