Optimizing Dispersion in Mixed matrix membranes containing Functionalized Multiwalled Carbon Nanotubes

Many water and gas purification techniques, such as membrane distillation, reverse osmosis and CO2 removal from natural gas, are reliant on membranes. Consequently, for the development of advanced membrane technologies, a good understanding of the materials properties and their transport mechanisms, as well as the realization of innovative functional materials with improved properties, are key issues. In the effort to develop next generation membranes with enhanced permeability, salt rejections and low energy consumption, much attentions has been put in the new membrane material and membrane architecture. Membranes based on carbon nanotubes have attracted attention due to their ability to display superior durability and separation characteristics [1, 2]. In spite of the advantages, there are still challenging issues such as problems of compatibility and dispersion. Thus, it would be desirable to develop a method for relating nanotube solubility to predictive parameters that would allow comparison between nanotube complexes and potential solvents or polymers. The aim of the work has been on how to improve the compatibility between MWCNT and polymeric material and thereby to obtain homogeneous dispersion in polymeric mixed matrix membranes without phase separation problem. In the present study, a simulation approach at atomistic- and mesoscale coupled with experimental investigation and validation is applied for the investigation of co-polyimide P84 with 1) pristine Multi Walled Carbon nanotubes (MWCNT), and 2) functionalized (oxidized and aminated) MWCNTs [3]. Accordingly, we designed various types of MWCNT models functionalized with OH- groups for mesoscale simulation: (1) functional group-terminated MWCNTs, (2) functional group-grafted MWCNT and (3) functional group-embedded MWCNT models. Finally, with the final coarse-grained bead model, we mimicked the real functionalized MWCNT structures. Modelling results were validated by experimental data obtained by the preparation of MWCNTs pristine and functionalized by oxidation and amination procedure. References 1.J.K. Holt, H.G.Park, Y. Wang, M. Stadermann, A.B. Artyukhin, C.P. Grigoropoulos, A. Noy, O. Bakajin, Fast mass transport through sub-2 nanometer carbon nanotubes, Science 312 (2006) 1034-1037. 2.H. Y. Yang, Z. J. Han, S. F. Yu, K. L. Pey, K. Ostrikov, R. Karnik, Carbon nanotube membranes with ultrahigh specific adsorption capacity for water desalination and purification Nat. Commun. 4:2220 doi: 10.1038/ncomms3220 (2013) 3.C. H. Park, E. Tocci, E. Fontananova, M. A. Bahattab, S. A. Aljlil, E. Drioli, Mixed matrix membranes containing Functionalized Multiwalled Carbon Nanotubes: Mesoscale Simulation and Experimental Approach for Optimizing Dispersion, Journal of Membrane Science 514 (2016) 195-20