Structure–gas separation property relationships of non-ionic and cationic amino-hydroxy functionalized poly (dimethylsiloxane) membranes

The gas permeation properties of a new poly (dimethylsiloxane) (PDMS) membrane containing different concentrations of amino-hydroxy functionalized poly (dimethylsiloxane) have been measured for structure-property relationship. The corresponding cationic membranes were prepared by treating the amino-hydroxy functionalized poly (dimethylsiloxane) membranes with HBr gas. The functionalized siloxane materials were characterized by IR, 1H and 13C NMR, GPC, DSC and TGA techniques. The permeability of N2, O2, CH4 and CO2 were determined for different concentrations of non-ionic and cationic membranes. The permeability value was found to be decrease with increase in the amount amino-hydroxy functionalized siloxane. The permselectivity value for O2/N2 was found to be around 2.3 for both non-ionic and cationic membranes. However, significant increase in the permselectivity values of 4.12 and 5.6 were observed for CO2/CH4 system in the case of non-ionic and cationic amino-hydroxy functionalized siloxane membranes, respectively. A significant increase in the solubility of CO2 with amino-hydroxy functionality especially in the case of cationic membrane was observed.