Abstract
Pervaporation and gas separation performances of polymer membranes can be improved by crosslinking or addition of metal-organic frameworks (MOFs). Crosslinked copolyimide membranes show higher plasticization resistance and no significant loss in selectivity compared to non-crosslinked membranes when exposed to mixtures of CO2/CH4 or toluene/cyclohexane. Covalently crosslinked membranes reveal better separation performances than ionically crosslinked systems. Covalent interlacing with 3-hydroxypropyldimethylmaleimide as photocrosslinker can be investigated in situ in solution as well as in films, using transient UV/Vis and FTIR spectroscopy. The photocrosslinking yield can be determined from the FTIR-spectra. It is restricted by the stiffness of the copolyimide backbone, which inhibits the photoreaction due to spatial separation of the crosslinker side chains. Mixed-matrix membranes (MMMs) with MOFs as additives (fillers) have increased permeabilities and often also selectivities compared to the pure polymer. Incorporation of MOFs into polysulfone and Matrimid® polymers for MMMs gives defect-free membranes with performances similar to the best polymer membranes for gas mixtures, such as O2/N2 H2/CH4, CO2/CH4, H2/CO2, CH4/N2 and CO2/N2 (preferentially permeating gas is named first). The MOF porosity, its particle size and content in the MMM are factors to influence the permeability and the separation performance of the membranes.
Highlights
Membranes processes are very important in our every day life and in industry, e.g., for water and waste water treatment, in medical applications or separation of petrochemicals
Separation is based on size exclusion and these membranes are suited for separation of components with sufficient size difference, e.g., in dialysis, waste water treatment and functional clothing
According to this potential application, the use of carbon nanotubes (CNTs)/polymer nanocomposites in membrane based separation processes is growing rapidly and considerable efforts were undertaken for the development in last decade [74,75,76,77,78,79,80] CNT particles are added as fillers to create preferential permeation pathways and thereby improve the separation performance in terms of the gas permeability [76,81]
Summary
Membranes processes are very important in our every day life and in industry, e.g., for water and waste water treatment, in medical applications or separation of petrochemicals. Simulations and detailed predictions demonstrated that the diffusivities of light gases inside the pores of CNTs are highly rapid compared to other porous materials [73] According to this potential application, the use of CNT/polymer nanocomposites in membrane based separation processes is growing rapidly and considerable efforts were undertaken for the development in last decade [74,75,76,77,78,79,80] CNT particles are added as fillers to create preferential permeation pathways and thereby improve the separation performance in terms of the gas permeability [76,81]. Another approach to oriented sheet membranes dealt with fully inorganic MCM-22/silica nanocomposite membranes [86]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
