Crosslinking of Brominated Poly(1-trimethylsilyl-1-propyne) Using Polyethylenimine as a Crosslinking Agent

Сrosslinked polymer memranes are obtained by the heat treatment of films prepared from a solution of a mixture of bromine-containing poly(1-trimethylsilyl-1-propyne) (PTMSP) and polyfunctional amine polyethyleneimine (PEI) as a crosslinking agent. Crosslinked products are identified from IR spectra, elemental analysis data, and stability of reaction products to a solvent (CCl₄), in which the original brominated PTMSP is soluble. According to the IR spectra, the crosslinking reaction occurs via reactive C–Br bond in bromine-containing PTMSP with the participation of PEI amino groups at a temperature above 90°С. The crosslinking of bromine-containing PTMSP makes it resistant to organic solvents. An increase in the content of PEI in the mixture correlates with the proportion of bromine atoms involved in the reaction. For brominated PTMSP films crosslinked by PEI transport parameters for individual gases and in the mixture n-butane/methane (98.4 mol % methane and 1.6 mol % n-butane) are studied. In the sequence PTMSP–brominated PTMSP-Br–PTMSP-Br/PEI (before crosslinking)–PTMSP-Br/PEI (after crosslinking) permeability for individual gases decreases. Crosslinked PTMSP in the mixture methane/n-butane demonstrates high permeability coefficients of n-butane (\({{P}_{{n{\text{-}}{{{\text{C}}}_{{\text{4}}}}{{{\text{H}}}_{{10}}}}}}\) = 12 000 Barrer) and selectivity for n-butane separation from a mixture with methane (\({{\alpha }_{{n{\text{-}}{{{\text{C}}}_{{\text{4}}}}{{{\text{H}}}_{{10}}}{\text{/C}}{{{\text{H}}}_{4}}}}}\) = 13).