Formation of Multilayer Membranes from One Polymer Using IR Treatment

In this paper, a new method of layer-by-layer formation of monopolymer membranes based on polyacrylonitrile (PAN) is proposed. The proposed approach allows independent adjustment of the structure and characteristics of individual layers of the membrane to achieve high performance characteristics. IR radiation has been used to modify PAN, the effect of which has allowed to convert the polymer into an insoluble form for the application of subsequent layers. An important feature of IR modification is that the pore size and permeability of the membranes remain unchanged. This makes it possible to form the individual membrane layers under different conditions. The obtained membranes have a well-defined spongy layer on the surface and finger-like pores in the other part of the membrane volume. The presence of the spongy layer on the surface reduces the probability of formation of undesirable defects, which reduce the membrane retention. As a result, defect-free membranes that combine a low molecular weight of MWCO cut-off equal to 1800 g/mol and a fairly good for such a dense membrane permeability of 38.7 L/m2 h atm have been obtained. The pore size of the obtained membranes is 3.7 nm.