Conformational Analysis of Poly-2,5-Benzimidazole (ABPBI), Poly-2,5- Benzoxazole (ABPBO), and Poly-2,6-Benzothiazole (ABPBT) Dimers by the Modified Neglect of Diatomic Overlap (MNDO) and Austin Method 1 (AM1) Semiempirical Molecular Orbital Methods

Abstract

The two repeat unit analogs of three, aromatic, heterocyclic polymers were studied as part of the Materials Laboratory's research program to develop high-performance polymers with good environmental resistance. The Modified Neglect of Diatomic Overlap (MNDO) and Austin Method 1 (AM1) semiempirical orbital methods were used to calculate the change in of torsion angle versus heat of formation were obtained where minima on the curves represent the most thermodynamically stable conformations of the molecules. The AM1 method was found to be superior to the MNDO method in all cases. The MNDO method produced near perpendicular minima while AM1 gave planar or near planar minima, consistent with x-ray studies of the polymers. In all three cases the transoid conformations were lower in energy than the cisoid.

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Document Details

Document Type
Technical Report
Publication Date
Jul 01, 1987
Accession Number
ADA185075

Entities

People

  • Scott G. Wierschke

Organizations

  • Wright Laboratory

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • 2-Ring Heterocyclic Compounds
  • Abstracts
  • Aeronautical Laboratories
  • Air Force
  • Air Force Facilities
  • Benzoxazoles
  • Classification
  • Government Procurement
  • Governments
  • Heat Of Formation
  • Materials
  • Materials Laboratories
  • Molecules
  • Polymers
  • Rotation
  • Security
  • X Rays

Fields of Study

  • Chemistry

Readers

  • Organic Chemistry
  • Polymer Science and Technology
  • Quantum Chemistry

Technology Areas

  • Space