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Simulated Crystalline Structures Of Aromatic Polyimides, Tze Wing Poon, B. David Silverman, Ravi F. Saraf, Angelo R. Rossi, Paul S. Ho

Ravi Saraf Publications

Semicrystalline structures involving molecular packing and optimized chain conformations of three polyimides have been obtained with the CHARMM moleculardynamics program, and their densities calculated. An eclipsed conformation of face-toface 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. Threedimensional 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/cm³, followed by BPDA-PDA with 1.644 g/cm³ and PMDA-PDA with 1.712 g/cm³. Both PMDA-ODA and BPDA-PDA …