Next Article in Journal
Important Approaches to Enhance Reverse Osmosis (RO) Thin Film Composite (TFC) Membranes Performance
Next Article in Special Issue
The Formation of Polyvinylidene Fluoride Membranes with Tailored Properties via Vapour/Non-Solvent Induced Phase Separation
Previous Article in Journal
TiO2 Polyamide Thin Film Nanocomposite Reverses Osmosis Membrane for Water Desalination
Previous Article in Special Issue
Immobilization of Graphene Oxide on the Permeate Side of a Membrane Distillation Membrane to Enhance Flux
Article Menu
Issue 3 (September) cover image

Export Article

Open AccessArticle
Membranes 2018, 8(3), 67;

Chemical Crosslinking of 6FDA-ODA and 6FDA-ODA:DABA for Improved CO2/CH4 Separation

Department of Inorganic Technology, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic
École Nationale Supérieure des Industries Chimique, 1 Rue Grandville—BP 20451, 54001 Nancy, France
Authors to whom correspondence should be addressed.
Received: 2 August 2018 / Revised: 16 August 2018 / Accepted: 18 August 2018 / Published: 20 August 2018
Full-Text   |   PDF [4505 KB, uploaded 20 August 2018]   |  


Chemical grafting or crosslinking of polyimide chains are known to be feasible approaches to increase polymer gas-pair selectivity and specific gas permeance. Different co-polyimides; 6FDA-ODA and 6FDA-ODA:DABA were synthesized using a two-step condensation method. Six different cross-linkers were used: (i) m-xylylene diamine; (ii) n-ethylamine; and (iii) n-butylamine, by reacting with 6FDA-ODA’s imide groups in a solid state crosslinking; while (iv) ethylene glycol monosalicylate (EGmSal); (v) ethylene glycol anhydrous (EGAn); and (vi) thermally labile iron (III) acetylacetonate (FeAc), by reacting with DABA carboxyl groups in 6FDA-ODA:DABA. The gas separation performances were evaluated by feeding an equimolar CO2 and CH4 binary mixture, at a constant feed pressure of 5 bar, at 25 °C. Fractional free volume (FFV) was calculated using Bondi’s contribution method by considering the membrane solid density property, measured by pycnometer. Other characterization techniques: thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) were performed accordingly. Depending on the type of amine, the CO2/CH4 selectivity of 6FDA-ODA increased between 25 to 100% at the expense of CO2 permeance. We observed the similar trend for 6FDA-ODA:DABA EGmSal-crosslinked with 143% selectivity enhancement. FeAc-crosslinked membranes showed an increment in both selectivity and CO2 permeability by 126% and 29% respectively. Interestingly, FeAc acted as both cross-linker which reduces chain mobility; consequently improving the selectivity and as micro-pore former; thus increases the gas permeability. The separation stability was further evaluated using 25–75% CO2 in the feed with CH4 as the remaining, between 2 and 8 bar at 25 °C. We also observed no CO2-induced plasticization to the measured pressure with high CO2 content (max. 75%). View Full-Text
Keywords: gas separation; polyimide; grafting; chemical crosslinking; plasticization resistance gas separation; polyimide; grafting; chemical crosslinking; plasticization resistance

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Ahmad, M.Z.; Pelletier, H.; Martin-Gil, V.; Castro-Muñoz, R.; Fila, V. Chemical Crosslinking of 6FDA-ODA and 6FDA-ODA:DABA for Improved CO2/CH4 Separation. Membranes 2018, 8, 67.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Membranes EISSN 2077-0375 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top