9 research outputs found
Structure, chain orientation, and properties in thin films of aromatic polyimides with various chain rigidities
Thermally and Mechanically Enhanced Clay/Polyimide Nanocomposite via Reactive Organoclay
Correlation of stress and optical properties in highly transparent polyimides for future flexible display
Analysis of Molecular Aggregation Structures of Fully Aromatic and Semialiphatic Polyimide Films with Synchrotron Grazing Incidence Wide-Angle X-ray Scattering
The intermolecular aggregation structures of fully aromatic polyimides (Ar-PIs) prepared from pyromillitic dianhydride (PMDA) and those of semialiphatic polyimides (Al-PIs) from 4,4'-diamino-cyclohexylmethane (DCHM) were characterized by a grazing incidence wide-angle X-ray scattering (GIWAXS) technique. The aggregation structures of both Ar- and Al-PI thin films formed on Si substrates were identified as a mixture of it liquid-crystalline-like ordered domain and an amorphous matrix. For Ar-PIs whose glass transition temperatures (T-g) are higher than the imidization temperature (T-i), the aggregation structures are significantly influenced by the three-dimensional structures of the PI chain. Rodlike molecular structures with high planarity are prerequisites for the growth of ordered domains of Ar-PIs, whereas an Ar-PI having a bent and nonplanar structure displays the highest intensities of an amorphous halo. In addition, the bulky -CF3 groups in the diamine moiety increase the interchain distance in the ordered domains. On the other hand, for Al-PIs whose T(g)s arc lower than T-i, the degrees of interchain ordering in the ordered domains were higher than those of Ar-PIs, but the orientation of the ordered domains was decreased significantly by decreasing their T(g)s. This is due to the vigorous motion of PI chains during thermal imidization