| Single crystals of PMDA-based aromatic polyimides including poly(4,4;All three as-polymerized polyimides and the corresponding poly(amic acids) show only two-dimensional order with relatively disordered chain packing in the c-direction. As the temperature increases an ordering process along the c-axis occurs. In PMDA-4,4;The crystal morphology for these three aromatic polyimides is primarily lamellar with extended chain perpendicular to the broad surface of the lamella. Lamellar thickness varies with polymerization conditions. It is observed that poly(amic acids) grow primarily along the 110 direction with the faceted 110 crystal plane laterally. Various twin crystals and epitaxial growth are found in PMDA-4,4... |
