The effect of fluorine atoms on gas transport properties of new polynorbornene dicarboximides

Abstract

The new N-4-trifluoromethylphenyl-norbornene-5,6-dicarboximide ( 2a) and N-3,5-bis(trifluoromethyl)phenyl-norbornene-5,6-dicarboximide ( 2b) mixtures of exo and endo monomers were synthesized and polymerized via ring opening metathesis polymerization (ROMP) using bis(tricyclohexylphosphine) benzylidene ruthenium(IV) dichloride ( I) and tricyclohexylphosphine [1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene][benzylidene] ruthenium dichloride ( II) to produce the corresponding polynorbornene dicarboximides Poly-2a and Poly-2b, respectively. The transport of five gases He, N 2, O 2, CO 2 and CH 4 across membranes prepared from Poly-2a was determined at 35 °C using a constant volume permeation cell. The gas transport properties of the fluorine containing polymer Poly-2a were compared with those found for membranes from non-fluorinated poly( N-phenyl- exo-endo-norbornene-5,6-dicarboximide) ( P-PhNDI). Gas permeability, diffusion and solubility coefficients of the fluorine containing polynorbornene Poly-2a were up to an order of magnitude larger than those of the non-fluorinated one. Poly-2a was found to have one of the largest gas transport coefficients reported to date in glassy polynorbornene dicarboximides.