Synthesis and Properties of Poly(1-trimethylsilyl-1-propyne) Containing Quaternary Ammonium Salts with Methyl and Ethyl Substituents

Poly(1-trimethylsilyl-1-propyne) modified with quaternary ammonium salts is synthesized. The introduction of salts into the polymer structure is carried out using a two-step method consisting in the bromination of the starting polymer followed by the addition of tertiary alkylamines—trimethylamine and triethylamine. The presence of ammonium salts is confirmed by the data of organometallic analysis and IR spectroscopy. X-ray diffraction analysis is used to study the supramolecular structure of the materials obtained. The TGA data indicate their high thermal and thermo-oxidative stability. The permeability, solubility, and diffusion coefficients of the poly(1-trimethylsilyl-1-propyne) samples containing trimethylamine and triethylamine salts for individual CO_2, N₂, and CH₄ gases are determined. An increased ideal selectivity for the separation of gas pairs CO₂/N₂ and CO₂/CH₄ in modified poly(1-trimethylsilyl-1-propyne) is achieved owing to the increased selectivity of the dissolution of CO₂ in quaternary ammonium salts.