Facile synthesis and characterization of a wholly aromatic poly(1,5-diaminoanthraquinone) by an oxidative polymerization

摘要

A wholly aromatic poly(1,5-diaminoanthraquinone) (PDAAQ) was synthesized by a chemically oxidative polymerization of 1,5-diaminoanthraquinone (DAAQ) using CrO_3, K_2Cr_2O_7, KCrO_4, and, KMnO_4 as oxidants under various polymerization conditions for the first time. Fine and uniform polymer particles of several micrometers, determined by laser particle-size analyzer, were obtained simply. The polymerization yield, electroconductivity, solubility, thermal transition, and thermostability of the polymers were systematically studied by changing the oxidizing agent, polymerization temperature, monomer/oxidant ratio, and acid concentration. FT-IR and NMR spectra of polymers reveal that the DAAQ is polymerized mainly at 1,4 and 5,8 positions by a head-to-tail bonding manner. The wide-angle X-ray diffraction suggests that the polymers are amorphous structure. The macromolecular structure of the resulting polymers was wholly characterized by IR, UV-vis, solid-state high-resolution ~(13)C NMR. The results show that typical polymer yields and electroconductivities are between 21.4-79.5% by weight, and 2.71x10~(-9)-5.54x10~(-6) S/cm before doped, respectively. All polymers show an extremely high chemical resistance in many solvents, but they are more soluble in polar solvents such as H_2SO_4, NMP, DMSO; and their solubility in solvents depends significantly on the polymerization conditions. DSC and TGA analyses indicate that the polymers exhibit a high thermal stability.