New High Permeable Addition Poly(tricyclononenes) with Si(CH₃)₃ Side Groups. Synthesis, Gas Permeation Parameters, and Free Volume

Addition polymerization of two tricyclononene monomers bearing one and two Si(CH 3 ) 3 groups was performed in the presence of Pd-containing catalysts. The polymers were obtained with high yields and were completely saturated. Good mechanical and film forming properties are observed for the polymers prepared in the presence of Pd(OAc) 2 /B(C 6 F 5 ) 3 catalyst. Their glass transition temperature was not observed until the onset of thermal decomposition (>370 °C) and the molecular weights are high ( M w up to 7 × 10 5 ). Study of gas permeation parameters of the obtained poly[3-(trimethylsilyl)tricyclononene-7] and poly[3,4- bis(trimethylsilyl)tricyclononene-7] showed that both glassy polymers revealed substantially high gas permeability. Other transport characteristics (increase in permeability in the series C 1 −C 4 alkanes and negative activation energies of permeation) indicate that these polymers reveal so-called solubility controlled permeation, which is typical for some extra-high permeability polymers. Positron annihilation lifetime spectroscopy indicated that both polymers are characterized by very large sizes of free volume elements.