Preparation of polyacetylene esters bearing pseudohexagonal structures using a Rh complex catalyst

Stereospecific polymerization of acetylene esters, HC=C-COOn-alkyl, was suc cessfully performed using a [Rh(norbornadiene)Cl](2) catalyst to give rise to the corresponding cis-transoid polyacetylene esters in the presence of a lcohol, which is the polymerization solvent by which the dimer catalyst was dissociated. We found that the polyacetylene esters generate pseudohexagon al structures called columnar as the self-assembly in the solid state, alth ough the columnar polymer has a helical structure as correlatively predicte d by the semi-empirical quantum chemical calculation method, AMI method. We also found that the poly(n-propiolate) polymer works as a highly oxygen pe rmeable membrane. The separation factor alpha, Po-2/P-N2 = 3.4, is comparab le to that for a typical oxygen permeable polymer reported before. Further we found that the ESR parameters of radicals observed in the pristine cis p olymer and thermally treated polymer are quite different from each other an d those radicals are created by the rotational scission of the cis C=C bond s to generate pi-radicals called solitons. Therefore these facts show that the ESR methods are useful for assignment of the resultant cis and trans ge ometrical isomers of this polymer because of the different observed ESR par ameters.