Synthesis and Gas-Transport Properties of Metathesis Polytricyclononenes Bearing Three Me3Si Groups per Monomer Unit

• Published in: Macromolecular chemistry and physics 2016-09, Vol.217 (17), p.1966-1976
• Main Authors: Chapala, Pavel, Bermeshev, Maxim, Starannikova, Ludmila, Borisov, Ilya, Shantarovich, Viktor, Lakhtin, Valentin, Volkov, Vladimir, Finkelshtein, Eugene
• Format: Article
• Language: English
• Subjects: gas-transport properties; membranes; metathesis polynorbonenes; silicon-containing polymers
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.201600232

A new metathesis polynorbornene containing three SiMe3 groups per monomer unit directly connected to the norbornene moiety via SiC bonds is synthesized. The ring‐opening metathesis polymerization of sterically hindered 3,3,4‐tris(trimethylsilyl)tricyclononene‐7 is successfully conducted in yields 80–85% in the presence of first generation Grubbs catalyst. The corresponding polymer is obtained with molecular weight Mw up to 5.4 × 105 Da. It is an amorphous glassy (Tg = 200 °C) polymer with high thermal stability. Gas permeability and diffusivity coefficients are studied for a range of gases (He, H2, O2, N2, CO2, CH4). This polymer containing three SiMe3 groups per monomer unit turns out to be more permeable (P(O2) = 125 Barrer) than similar polymers with one or two SiMe3 groups per monomer unit (P(O2) = 30–50 Barrer). Wide angle X‐ray diffraction, positron annihilating lifetime spectroscopy, as well as Brunauer–Emmett–Teller investigations are also performed and discussed. The physical and gas transport properties of polynorbornenes containing three bulky groups per monomer unit (which are directly connected or via SiOSi bonds to polymer main chains) are studied. It is found that an extra increase of gas permeability can be achieved by the introduction of the third SiMe3 substituent in monomer unit of metathesis polymers.