Chemical Modification of Poly(1-Trimethylsilyl-1-Propyne) in Supercritical Fluids for the Development of Highly Efficient Membrane Materials

This paper studies the chemical modification of a polymer promising for the development of gas separation membranes to improve its CO2 selectivity. The possibility of the introduction of butylimidazolium bromide (BIm+Br–) into the structure of poly(1-trimethylsilyl-1-propyne) (PTMSP) using a two-stage process—bromination of the initial polymer with N-bromosuccinimide and subsequent interaction with a tertiary amine, N-butylimidazole—is demonstrated. Supercritical CO2 and CHF3, which have a number of advantages over organic solvents, such as nontoxicity, nonflammability, and environmental safety, are used as the reaction media. Depending on the conditions of the process, the proposed method makes it possible to regulate the BIm+Br– content in the polymer structure. The resulting modified polymers are characterized by good film-forming properties, thermal stability, and increased resistance to aliphatic, alicyclic, halogenated, and aromatic hydrocarbons. It is found that with an increase in the BIm+Br– content in the polymer, the selectivity of CO2/N2 and CO2/CH4 separation increases while maintaining high gas permeability. These results open up new possibilities for the development of efficient membrane materials for gas separation in industrial conditions.