Detailed study of the gas permeation parameters of a glassy poly(tricyclononene) with Si–O–Si side groups

• A new method for estimation of gas sorption isotherms in polymers.
• P, D and S values of poly(3,4-bis(trimethylsiloxy)silyl tricyclononene-7).
• Selectivity of D is relatively weak as compared with that of other glassy polymers.
• This is the reason for the solubility controlled selectivity of this polymer.

Diffusion (D) and permeability (P) coefficients of poly(3,4-bis(trimethylsiloxy)silyl]tricyclononene-7) (PTSOTN), a metathesis ring opening polymer with Si–O–Si containing side groups, were measured for light gases (He, H2, O2, N2, CO2) and hydrocarbon C1–C4. For the hydrocarbons C2–C4 the measurement was conducted in the pressure range of 0–2 atm. Using a novel technique, sorption isotherms in this polymer were obtained for all the aforementioned penetrants in the range of 0–2.5 atm. It was shown that the slope of the correlation of ln D versus d2 for PTSOTN is intermediate between those characteristic for polymers with solubility controlled selectivity and size sieving glassy polymers. A comparison of the permselectivity α, diffusion selectivity αD and sorption selectivity αS indicated that the solubility controlled permeation in PTSOTN is caused by the reduced diffusivity selectivity of this polymer.

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