Synthesis of a cellulose nanofiber-templated polypyrrole-polyaniline core-shell structure and study on its electromagnetic shielding properties

Abstract

Polypyrrole (PPy) - polyaniline (PANI) core-shell composite was synthesized by template polymerization. PPy was synthesized by polymerizing pyrrole with TEMPO-oxidized cellulose nanofiber (TOCN) as a template, varying the weight ratio of pyrrole to TOCN. Polymerization of pyrrole occurs along the surface of TOCN to form nanofibrous TOCN-PPy composites when the pyrrole to TOCN weight ratio is 3 to 10. Aniline was polymerized in the reaction mixture of TOCN-PPy. PANI was formed on the surface of TOCN-PPy nanofibers and the dendritic growth of PANI was observed with increasing amount of aniline added. High electrical conductivity of 7.0 S/cm was obtained for TOCN-PPy, but the conductivity was decreased to 0.3~0.7 S/cm after the polymerization of aniline. The surface area and pore volume of these composites are higher than that of PPy polymerized without template. Reduction of the surface area and pore volume was recovered with the dendritic growth of PANI with increasing amount of aniline added. Electromagnetic shielding properties of these core-shell composites were studied. The shielding properties of TOCN-PPy composites were improved with increasing the amount of pyrrole added, while the shielding efficiency was deteriorated after the formation of PANI on the surface of TOCN-PPy. The correlation between morphology, electrical conductivity and shielding performance was discussed.