Gas permeability of polyacetylenes with bulky substituents

Summary

In search of new materials for oxygen-enrichment membranes, high polymers of acetylenes with bulky substituents [2-octyne $\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{1}$, 2-decyne $\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{2}$, t-butylacetylene $\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{3}$, 1-phenyl-1-propyne $\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{4}$, and 1-chloro-2-phenylacetylene $\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{5}$] were synthesized with Mo- or Ta-based catalysts, and their permeability coefficients to oxygen (P_O2), nitrogen (P_N2), and carbon dioxide were determined at 25°C. Polymer membranes of the aliphatic acetylenes ($\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{1}$-$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{3}$) were highly permeable to oxygen. In particular, poly $\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{3}$ showed a large P_O2 value in the order of 10⁻⁸ [cm³ (STP) · cm/cm² · sec · mmHg] together with a fairly high permselectivity for oxygen (P_O2/P_N2∼3). Polymers of the aromatic acetylenes ($\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{4}$ and $\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{5}$) were less oxygen-permeable, giving P_O2 in the order of 10⁻¹⁰, slightly larger than that for polystyrene.