Structure-property relationships of polyimides: a molecular simulation approach

Chain flexibility and mechanical properties of four polyimides with different chemical structures are simulated by molecular dynamics and molecular mechanics techniques to establish some structure-property relationships. The oxygen linkage in the diamine moiety of a polyimide gives the highest flexibility whereas the sulfonyl linkage imparts the lowest flexibility to the polymer chain. A more flexible polyimide has smaller characteristic ratio, lower solubility parameter, lower elastic modulus, and larger yield strain. These simulated values show good agreement with experimental data. (C) 1998 Elsevier Science Ltd. All rights reserved.