The use of polymeric cryogels based on PVA for the creation of composite filter systems for the disinfection of the gaseous medium in confined spaces is of great interest in connection with the information that has appeared on the low efficiency of the Potok device used at the International Space Station for air purification¹.
It is known that carrying out the process under cryostructuring conditions makes it possible to obtain PVA cryogels with directed pores, which makes it possible to use the samples as filtering systems.
To date, a number of methods are known for obtaining physically and chemically crosslinked PVA gels. However, the gels obtained by the methods described in the literature have relatively low porosity. One of the ways to overcome this problem is the original approach proposed by us earlier, which consists in crosslinking in water-frozen systems of acrylic derivatives of PVA ². This method makes it possible to obtain a product with a porosity of 85-86% from polymer solutions with a concentration of ~ 4%.
However, to obtain matrices with even higher porosity, a new combined approach was developed in this work. At the first stage, the PVA solution is frozen with an initiator, followed by freeze drying, as a result of which a three-dimensional porous structure is formed. In the second stage, crosslinking occurs under controlled heating.
As a result, it was possible to obtain crosslinked systems even with a polymer concentration in the solution of only 1%.
At the next stage, the equilibrium swelling of the obtained samples was assessed. It has been established that with prolonged heat exposure, a decrease in equilibrium swelling is observed. This fact can be associated both with a change in the hydrophilicity of the crosslinked polymer chains due to the oxidation of hydroxyl groups under the influence of an excess of initiator, and due to a change in the porosity of the system.