Fabrication of analogous mixed matrix membranes via partially in-situ generation of rigid porous moieties without interfacial defects

Abstract

Herein, a kind of a nalogous m ixed m atrix m embrane (AMMM) was constructed via partially in-situ generation of thermally rearranged polybenzimidazole (TR-PBI) moiety within the network PI matrix that contains ortho -amino group adjacent to imide ring. The role of highly rigid and permeable TR-PBI moieties was very similar to that of the porous fillers in traditional MMMs. By using this strategy, the issues of interfacial incompatibility and filler agglomeration were readily circumvented since the rigid porous fillers are, in fact, the rigid porous moieties that are totally belonged to the part of polymeric matrix itself. After the partially TR conversion, the average microporous diameter within membranes was increased according to the results of N 2 adsorption isotherms and positron annihilation lifetime spectroscopy (PALS) analyses. Gas transport tests revealed that the prepared PBI-PI AMMM exhibited a ∼28.2-fold increasing of in CO 2 permeability (up to 4234.9 Barrer), ∼25.8-fold increasing in O 2 permeability (up to 794 Barrer), and ∼36-fold increasing in N 2 permeability (up to 203.6 Barrer) relative to those of its network PI precursor, along with the decent selectivity of 3.9 for O 2 /N 2 and 20.8 for CO 2 /N 2 . As a result, the comprehensive gas transport properties of PBI-PI AMMM for gas pairs of O 2 /N 2 and CO 2 /N 2 exceeded or approached the 2008 Robeson upper bounds. We hope this proof-of-concept study can open a new avenue to design the advanced AMMMs, especially without the issues of interfacial incompatibility and filler agglomeration. • A novel spirobifluorene pentamine was designed using to form the nascent network PI matrix. • AMMM was constructed via partially in-situ generation of TR-polybenzimidazole moiety. • Mean microporous diameter within AMMM was increased based on the BET and PALS analyses. • Exceptional permeability enhancement in AMMM was observed via partially TR conversion.