ИСТИНА

Composite membranes with thin selective layers made of highly permeable polymers attract considerable attention due to superior separation performance. However, rapid physical ageing, high probability of defect formation and plasticization in thin polymer films severely limiting industrial applications of composite membranes. A trade-off between permeability and separation factor is a well-known problem in polymer membrane science. Several approaches have been proposed to solve these problems, for instance, nanoparticles loading and cross-linking of the selective layer, chemical modification of macromolecules, etc. Another way to improve gas transport properties of polymer films is to govern macromolecules mobility. It is well-known, that permeation of gases through a polymer material occurs by a molecule jumping between voids or free volume elements, due to thermal movement of chain segments in rubbery polymers and small-scale mobility of functional groups in glassy polymers. As a consequence, by governing the motion of polymeric macromolecules it becomes possible to regulate permeability of gas molecules across the polymer membrane. Nanoconfinement of polymer chains in the channels of an appropriate rigid matrix can be considered as a perspective approach in this case. In the present research new composite membranes based on porous anodic aluminum oxide (AAO) films and polymer of intrinsic microporosity (PIM-1) have been prepared using a spin-coating technique. According to scanning electron microscopy, partial penetration of polymer macromolecules into the cylindrical channels of AAO supports takes place giving rise to selective layers with fiber-like microstructure. As a result, transport of permanent gases, such as N2 and CH4, has become dramatically hindered across confined polymer chains. Nevertheless, spatial constriction did not considerably affect the transport of condensable gases, such as carbon dioxide and butane, due to their high solubility in the polymer matrix. This new strategy enables substantial enhancement of CO2/CH4 and C4H10/CH4 pure gas separation factor (up to 20-fold) without significant loss of the membrane performance.