Subnanoporous Highly Oxygen Permselective Membranes from Poly(conjugated hyperbranched macromonomer)s Synthesized by One-Pot Simultaneous Two-Mode Homopolymerization of 1,3-Bis(silyl)phenylacetylene Using a Single Rh Catalytic System: Control of Their Structures and Permselectivities

Novel well-defined complex polymers, polymers of acetylene-type macromonomers having silylene–vinylene–phenylene–ethynylene hyperbranches, investigated as a new class of subnanoporous oxygen permselective membrane materials, were synthesized very easily by one-pot simultaneous two-mode homopolymerization of a single monomer with a single catalyst. For this “simultaneous polymerization” we synthesized AB<sub>2</sub>-type monomers (1,3-bis­(dimethylsilyl)­phenylacetylenes) containing one terminal triple bond and two Si–H groups. The resulting poly­(hyperbranched macromonomer)­s had high molecular weights, low densities, high solubility, and good self-membrane forming ability. They had higher oxygen permselectivities (α = <i>P</i><sub>O<sub>2</sub></sub>/<i>P</i><sub>N<sub>2</sub></sub>) than any other reported polymers having similar oxygen permeabilities (<i>P</i><sub>O<sub>2</sub></sub>). These excellent polymer membranes could be obtained only by the simultaneous polymerization. In the one-pot simultaneous polymerization, the two different modes of polymerizations, i.e., addition polymerization of the triple bond and polyaddition of the triple bond and two SiH groups in the single monomer, occurred simultaneously by using one catalytic system, i.e., [Rh­(norbornadiene)­Cl]<sub>2</sub>/various amines. The ratio of the branches (<b>RB</b>), i.e., the addition polymerization and the polyaddition, could be controlled by changing the amine cocatalysts. Their oxygen permselectivities could be adjusted by controlling the polymer structures including <b>RB</b>.