Columnar Assemblies of Aliphatic Poly(acetylene ester)s Prepared with a [Rh(norbornadiene)Cl]2 Catalyst. 1H and 13C NMR, X-Ray Diffraction and AFM Studies

Alkyl propiolates: HC≡CCOOn‐CmH2m+1(m = 2˜4), acetylene esters were polymerized with a [Rh(norbornadiene)Cl]2 catalyst in methanol as the polymerization solvent to produce poly(n‐alkyl propiolate)s, PAPAs, called polyacetylene esters, in relatively high yields. The resulting PAPAs were characterized in detail using 1H and 13C NMR spectroscopy, X‐ray diffraction, and atomic force microscope methods. The data showed that the resulting polymers selectively have cis‐transoid form. The cis‐transoid isomer is not amorphous but holds a pseudohexagonal structure called a columnar assembly the diameter of which agrees with those estimated by the semiempirical calculation method (AM1). The crystalline ratios of the columnar assemblies were also estimated to be ca. 60 ˜ 70%. In the case of poly(ethyl propiolate), PEPA, the crystalline size was found to approximately agree with that estimated from the AFM images of the cast film of PEPA.