Solid‐state polymerization of a cyclic diacetylene

Abstract

Abstract Large polymeric single crystals of a unique ring‐bridged polymer have been produced by the solid‐state polymerization of a cyclic diacetylene ( o , o ′‐diacetylenyldiphenyl glutarate). These crystals are of high thermal stability, metallic in appearance with an asbestos‐like texture, infusible, and insoluble. Single‐crystal x‐ray diffraction investigation indicates that the polymer is monoclinic (probable space group C 2/ c or Cc ) with a unit cell containing four monomer units of dimensions α = 20.8 Å, b = 8.0 Å, c = 9.7 Å, and β = 106°. Infrared spectra eliminate the previously suggested possibility that the solid‐state reactivity of the above monomer corresponds to either reaction of the carbonyl function with the acetylenic bond or the cleavage of the ester linkage. Diffraction, dichroism, and Raman spectral studies indicate instead that the reaction proceeds by 1,4‐addition polymerization at the diacetylene group to produce a trans–trans polymer of structure magnified image where the curved lines represent the di‐( o ‐phenyl)‐glutarate linkages which are on opposite sides of the chain for adjacent monomer units.