Rigid-rod polyimides

Figure 15.3. Tetracarboxylic dianhydrides and diamines for rigid-rod polyimides.

Miscibility of segmented rigid-rod polyimide (PI), viz., biphenyl dianhydride perfluoromethylbenzidine (BPDA-PFMB), and flexible polyether imide (PEI) molecular composites was established by differential scanning calorimetry. The composite films of BPDA-PFMB/PEI were drawn at elevated temperatures above their glass transitions. Tensile moduli of the films were evaluated as a function of composition and draw ratio. Molecular orientations of polyimide were determined by birefringence and wide-angle X-ray diffraction. The crystal orientation behavior of the 80/20 BPDA-PFMB/PEI was analyzed in the framework of the affine deformation model. 

Rigid-Rod Polyimides with n-Alkoxymethyl Side Chains... 

By one-step condensation of DIS-IBDIs having n-alkoxymethyl side chains with PMDA, BPDA and NTDA three series of new rigid-rod polyimides are synthesized and characterized. X-ray studies on their smictures revealed that the C -PY-PIs have well-ordered layered crystalline structure and the C -BP-PIs and the C -NA-PIs are amorphous, but the former with Cg and Cg side chains show a nematic mesophase at temperatures near 18(f C and the latter gave no observable phase transitions. 

Pd-catalyzed polycondensation was extended to the synthesis of highly branched rigid-rod polyimide by incorporation of phenyl-substituted pyromel-... 

Synthesis of rigid-rod polyimides 49 with dye-containing side groups via a precursor route was reported (Scheme 18) [48]. 

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