Synthesis and oxygen permeation of novel polymers of phenylacetylenes having two hydroxyl groups via different lengths of spacers

•Three novel phenylacetylenes having two hydroxyl groups via different kinds of spacers were synthesized and polymerized.•The two of the resulting polymers were strong enough to be applied as oxygen permeation membranes.•The introducing of the spacer in the monomers changed the polymer's conformation and the columnar contents of their membranes.•The membrane forming ability and oxygen permselectivity were improved by the extension of the length of the spacer.•The oxygen permselectivity was ideally improved by adjusting the columnar content without any drop of oxygen permeability.

Three novel phenylacetylenes having two hydroxyl groups via different kinds of spacers between the two hydroxyl groups and benzyl group were synthesized and polymerized. Two of the resulting polymers having oxyalkylene spacers between the hydroxyl group and benzyl group had good membrane forming ability, relatively high oxygen permselectivity and high oxygen permeability. By introducing the oxyalkylene spacers, the membrane forming abilities and oxygen permselectivity were enhanced. Oxygen permselectivity (PO2/PN2=2.67) of the polymer membrane having the longest spacers was higher than that (2.19) of polymer without any spacers. It may be because the columnar content and then defects decreased when the cis-cisoid conformation was changed to cis-transoid conformation. In addition, by decreasing the columnar content of the membrane from the polymer without any spacers, which could be controlled by conditions in membrane preparation, the membrane forming ability and oxygen permselectivity were effectively enhanced (from 2.19 to 2.61) without any drop of oxygen permeability.

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