Details

Autor(en) / Beteiligte

• TZE WING POON
• SILVERMAN, B. D
• SARAF, R. F
• ROSSI, A. R
• HO, P. S

Titel

Simulated crystalline structures of aromatic polyimides

Ist Teil von

• Physical review. B, Condensed matter, 1992-11, Vol.46 (18), p.11456-11462

Ort / Verlag

Woodbury, NY: American Physical Society

Erscheinungsjahr

1992

Link zum Volltext

Quelle

PROLA

Beschreibungen/Notizen

• Semicrystalline structures involving molecular packing and optimized chain conformations of three polyimides have been obtained with the CHARMM molecular-dynamics program, and their densities calculated. An eclipsed conformation of face-to-face stacking of polymer chains with a relative shift is observed, and the shift is found to depend upon the molecular characteristics of the planar unit and chain linearity. Three-dimensional structures obtained by calculating the optimized edge-on confirmation of the stacked units yield the smallest calculated density for PMDA-ODA, namely 1.515 g/cm exp 3 , followed by BPDA-PDA with 1.644 g/cm exp 3 and PMDA-PDA with 1.712 g/cm exp 3 . Both PMDA-ODA and BPDA-PDA reveal planar zigzag structure, and the former shows the largest undulation measured by the maximum difference in surface elevation on the surface elevation on the surface cleaved along the edge-on bonds. PMDA-PDA reveals flat planar structure.