Accession Number : ADA135278

Title :   Model Compound Studies of Rigid Rod Aromatic Heterocyclic Polymer Systems, the X-Ray Crystal Structure of 2,6-Diphenylbenzo (1,2-d; 5,4-d') Diimidazole Tetrahydrate, C2OH14N4. 4H2O, a Model System for the Study of Polymer-Water Interaction in Polybenzimidazoles.

Descriptive Note : Final rept. 1 Aug 81-30 Sep 82,


Personal Author(s) : Hunsaker,M ; Adams,W W ; Fratini,A V

Full Text :

Report Date : Jul 1983

Pagination or Media Count : 92

Abstract : The crystal and molecular structure of 2,6-diphenylbenzo (1,2-d;5,4-d') diimidazole tetrahydrate, C2OH14N4. 4H2O, is determined by single crystal x-ray diffraction. The benzodiimidazole compound is used as a model compound for poly(p-phenylenebenzodiimidazole), a rigid rod polymer. The crystals grown from ethanol are well formed, translucent, and amber tinted. The space group is P21/c (monoclinic), with cell constants a = 9.008(2)A, b = 24.967(7)Angstroms, c = 9.870(5)Angstroms, Beta = 119.82(3)deg. There are four molecules per unit cell of volume 1925.8(1.3)A3, and the measured density is 1.295 g/cc. 4850 unique reflections out to 56 deg in 2 theta were collected with an automated diffractometer using niobium filtered MoK alpha, radiation. The 2 theta scan technique was employed. Absorption corrections were made and approximately 11,000 reflections were averaged to give a hemisphere of independent observations. The direct method of phase determination was used to solve the structure, and full matrix least squares refinement gave a final Rw factor of 0.084 based on the 3570 reflections with Fobs or = 3sigma(F).

Descriptors :   *Polymers , *Molecular structure , *Models , *Crystal structure , *Heterocyclic compounds , Aromatic compounds , X ray diffraction , Polybenzimidazole , Molecule molecule interactions , Phenyl radicals , Molecular structure

Subject Categories : Plastics
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE