| This work was focused on gas separation membranes made from high molecular weight poly (2,6-dimethyl-1,4-phenyl oxide) (PPO) and its chemically modified derivatives. The molecular weight of the polymer was calculated to be 316400 g/mol corresponding to 1.57 dL/g intrinsic viscosity in chloroform. The research objectives are to (i) study the effect of chemical modification of PPO on the gas separation performance of membranes made from the resulting polymers; (ii) study and compare the formation of dense and composite membranes based on PPO, and correlate the formation of these membranes to their performance and morphology; (iii) put forward a model to predict and evaluate the performance of composite membranes based on the intrinsic properties of the individual polymeric layers forming the composite membrane. The objectives of the research covered the following topics of membrane science: (i) material development and modification, (ii) membrane-gas penetrant interaction, (iii) membrane morphology and formation, and (iv) mathematical modeling of transport phenomena in porous and thin film composite membranes. The gas separation performance of the membranes was tested based on the permeation of CO2, CH4, O2, and N2 gases. The membrane selectivity was mainly judged by CO2/CH4 and O2/N2 permeability ratios. These gases are of relevant industrial and/or environmental interest.; The chemical modification of PPO was carried out via sulfonation, bromination, and simultaneous sulfonation and bromination. The gas permeability in 20% and 37.4% brominated PPO membranes increased slightly, while it increased significantly in 60% brominated PPO, in comparison to that of the parent polymer. The permeability ratio of PPO was maintained in the resulting brominated PPO. Infrared study showed that bromination resulted in stiffening the torsional motion of the phenyl ring around the ether link, and at moderate and high bromination levels, the interference of the bromine group with neighboring methyl groups became significant. This conformed to the postulation that high bromination level is needed to produce significant increase in the length of a diffusional jump segment, hence the diffusional jumps rate.; The effect of sulfonation of PPO, and the effect of replacing the proton of the sulfonic groups with: mono-valent, di-valent, and tri-valent metal cations, was investigated. (Abstract shortened by UMI.)... |
