Intrinsically conducting polyaminoanthraquinone nanofibrils: interfacial synthesis, formation mechanism and lead adsorbents

Abstract

Intrinsically conducting nanofibrils of poly(1-amino-5-chloroanthraquinone) (PACA) were successfully synthesized via the interfacial chemical oxidative polymerization of 1-amino-5-chloroanthraquinone (ACA) monomers in biphasic systems. The effects of the reaction parameters, including polymerization media and temperature, oxidant species, monomer concentrations, oxidant/monomer molar ratios, and acid concentrations, on the polymerization yield, bulk electrical conductivity, diameters and aspect ratio of the resulting PACA nanofibrils were systematically optimized. PACA nanofibrils exhibit the highest polymerization yield of 64.8%, aspect ratio of 67 (∼30 nm diameter, ∼2 μm length), and bulk electrical conductivity of 6.2 × 10⁻³ S cm⁻¹, when the ACA monomers were oxidized by CrO₃ in a combined medium consisting of nitrobenzene and 250 mmol L⁻¹ HClO₄ solution. PACA nanofibrils are highly water-dispersible and self-stable with no need to add any stabilizers. The formation mechanism of PACA nanofibrils was explored to understand what contributions are responsible for the functionalities. With a clean surface, high negatively charged density, and thermostability, as well as strong blue-light emitting fluorescence property, PACA nanofibrils are very promising materials for the fabrication of advanced iron sensors and lead adsorbents.