Charged Surface of Polyacrylonitrile Colloid and Its Application to N2/CO2 Separation

Nano‐sized polyacrylonitrile (PAN) colloidal dispersions of 44.6 ± 8.3 nm prepared by the modified emulsion polymerization method are utilized for gas separation. The emulsion (o/w) polymerization using organic solvent instead of precipitation polymerization is utilized, and both the size of the colloidal particle and the zeta potential could be controlled by the content of the material constituting emulsion. Thus, the solubility of CO2 is dependent on the zeta potential on the surface of colloids, resulting in that the degree of absorption of CO2 is controllable. Then, N2/CO2 separation experiment is carried out by applying the synthesized PAN colloidal dispersions into a polymer composite. The composite membranes are prepared by adding PAN colloidal dispersions based on poly(vinyl pyrrolidone) (PVP). It is observed that the neat PVP membrane has no separation performance, while the PVP/PAN colloidal composite film shows the improved N2/CO2 selectivity of 17. This improved separation performance is due to the fact that the solubility of CO2 decreased by absorption to specific functional groups, resulting in the enhancement of N2 separation. Nano‐sized polyacrylonitrile (PAN) particles, approximately 44.6 nm, are utilized for gas separation, where their size and zeta potential are tuned by altering the emulsion formula, which in turn controls carbon dioxide (CO2) absorption levels. PAN particles are incorporated into polymer composites with poly(vinyl pyrrolidone) for N2/CO2 separation, achieving a selectivity of 17 by decreasing CO2 solubility, thereby enhancing nitrogen separation efficiency.