Related Experiment Video
Updated: Feb 23, 2026

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
Control of Head/Tail Isomeric Structure in Polyimide and Isomerism-Derived Difference in Molecular Packing and
Longbo Luo1, Yu Dai1, Yihao Yuan1
1State Key Laboratory of Polymer Material and Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu, 610065, P. R. China.
Abstract:
Two sequence isomeric poly(amic acid)s (PAAs) are successfully synthesized from 3,3',4,4'-biphenyltetracarboxylic dianhydride and unsymmetrical 5(6)-amino-2-(4-aminobenzene) benzimidazole (PABZ). The syntheses are based on the site-selective reactivity of head/tail amino groups of PABZ and solubility differences of PABZ in good solvent (dimethyl sulfoxide, DMSO) and poor solvent (N-methyl-2-pyrrolidone, NMP). The proton nuclear magnetic resonance (1 H-NMR) results reveal that the content of head tail-head tail (HTHT) bonding units in PAA-DMSO (PAA synthesized in DMSO) is 37%, while this content increases to 54% in PAA-NMP (PAA synthesized in NMP). The wide-angle X-ray diffraction (WAXD) results indicate polyimide (PI)-NMP film with high HTHT content exhibits a semicrystalline structure, while PI-DMSO film is amorphous. Moreover, PI-NMP also shows higher in-plane orientation than PI-DMSO. The ordered molecular packing and higher in-plane orientation of PI-NMP lead to an increase in mechanical properties and a decrease in in-plane thermal expansion coefficient.
More Related Videos
06:55Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
09:09Synthesis of PolyN-isopropylacrylamide Janus Microhydrogels for Anisotropic Thermo-responsiveness and Organophilic/Hydrophilic Loading Capability
Published on: February 27, 2016
Related Concept Videos
Polymer Classification: Stereospecificity
Isomerism
Disubstituted Cyclohexanes: cis-trans Isomerism
In cyclohexane, the substituents can occupy different positions generating distinct isomers....
Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Stereoisomerism of Cyclic Compounds
Polymer Classification: Crystallinity
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...