The concept of mixed matrix membrane comprising dispersed inorganic fillers into a polymer media has revealed appealing to tune the gas separation performance. In this work, the membranes were prepared by incorporation of mesoporous silica into polyurethane (PU). Mesoporous silica particles with different pore size and structures, MCM-41, cubic MCM-48 and SBA-16, were synthesized by templating method and functionalized with 3-aminopropyltriethoxysilane (APTES). High porosity and aminated surface of the mesoporous silica enhance the adhesion of the particles to the PU matrix. The SEM and FTIR results showed strong interactions between the particles and the PU chains. Moreover, the thermal stability of the hybrid PUs improved compared to the pure polymer. Gas transport properties of the membranes were measured for pure CO 2 , CH 4 , O 2 , and N 2 gases at 10 bar and 25°C. The results showed that the gas permeabilities enhanced with increasing in the loading of modified mesoporous silica particles. High porosity and amine-functionalized particles render opportunities to enhance the gas diffusivity and solubility through the membranes. The enhanced gas transport properties of the mixed matrix membranes reveal the advantages of mesoporous silica to improve the gas permeability (CO 2 permeability up to~70) without scarifying the gas selectivity (α(CO 2 /N 2 )~30 for 5 wt% SBA-16 content).
Blend membranes of synthesized polyurethane (PU) based on toluene diisocyanate (TDI), polydimethylsiloxane (PDMS) and polytetramethylene glycol (PTMG) with polyamide 12-b-polytetramethylene glycol (PA12-b-PTMG) were prepared by a solution casting technique. The heterogeneous microstructures of the blend membranes (PU /PA12-b-PTMG) were characterized by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Gas transport properties were determined for O 2 , N 2 , CH 4 , and CO 2 gases and the obtained permeabilities were correlated with polymer properties and morphology of the membranes. Comparison of the results with that of the pure PU membrane indicates that the blend membranes had higher permeability to CO 2 , but lower permeability to O 2 , N 2 and CH 4 gases, and, therefore, had higher values of CO 2 /N 2 and CO 2 /CH 4 ideal gas pair selectivities. The blend membrane with 20 % (wt) PA12-b-PTMG showed the highest CO 2 permeability (≈105 Barrer) compared to the PU and other blend membranes. In the blend membranes with 5-20 % (wt) PA12-b-PTMG contents an enhancement of CO 2 /CH 4 (≈ 10) and CO 2 /N 2 (≈ 52) selectivities was observed. The experimental permeabilities of the blend membranes were compared with the calculated permeabilities based on a modified additive logarithmic model.
New Silicon based nanostructures particles were successfully synthesized by tetraethoxysilane (TEOS) as silica precursor, mixture of two copolymers of PPG-b-PPE-b-PPG and PEO-b-PPG-b-PEO (Plutonic) as templates. PU-PDMS and PU-PDMS/silica composite membranes were prepared by solution casting technique. Synthesized mesoporus silica particles and hybrid membranes were characterized using Nitrogen adsorption-desorption (BET), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). As confirmed by BET analysis, the mean pore diameters of SPB1,2 Silicon particles are around 9 nm. The SEM micrographs confirmed the nanoscale distribution of silica particles in the polymer matrix. Gas permeation of PU-PDMS/silica hybrid membranes with silica contents of 5, 10 and 20 wt.% was studied for N2, CO2 and He single gases at8 bar. The obtained results suggest a significant increase in permeability of all gases upon increasing the silica particles content. The possible reasons for such behavior were stated and discussed.
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