Chemistry: A European Journal 2007-01-01

Productive synthesis and properties of polydiaminoanthraquinone and its pure self-stabilized nanoparticles with widely adjustable electroconductivity.

Xin-Gui Li, Hu Li, Mei-Rong Huang

Index: Chemistry 13(31) , 8884-96, (2007)

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Abstract

Wholly aromatic poly(1,5-diaminoanthraquinone) (PDAA) particles were productively synthesized for the first time by chemically oxidative polymerization of 1,5-diaminoanthraquinone (DAA) by using CrO3, K2Cr2O7, K2CrO4, or KMnO4 as oxidants in acidic DMF. The effects of the oxidant species, oxidant/DAA ratio, polymerization temperature, and medium on the polymerization yield, macromolecular structure, size, electroconductivity, solubility, solvatochromism, thermostability, photoluminescence, and silver-ion sorption of the PDAA particles were systematically studied by IR, UV/Vis, fluorescence, and solid-state 13C NMR spectroscopies, wide-angle X-ray diffraction, scanning and transmission electron microscopies, and laser particle-size, differential scanning calorimetry (DSC), and thermal gravimetric (TG) analyses. It seems that the DAA is oxidatively polymerized at the 1,4- and 5,8-positions. Surprisingly, the chemical oxidative polymerization of DAA with CrO3 at 0 degrees C in H2SO4/DMF in the absence of external stabilizer simply affords novel PDAA nanoparticles of around 30 nm in diameter with high purity, clean surfaces, inherent semiconductivity, and self-stability that can be ascribed to the presence of a large number of 1,4-benzoquinone units that are negatively charged on their macromolecular chains. The polymers exhibit a high thermal stability at temperatures below 400 degrees C. Two unique nanoeffects were found, namely the strongest silver-ion adsorbability and photoluminescence of the PDAA nanoparticles. This gives a facile and general route for the application of the versatilities of PDAA nanomaterials. The PDAA particles are good semiconductors with a widely adjustable conductivity that moves across seven orders of magnitude through simple HClO4 redoping or Ag+ sorption, as expected.