Electrically conducting nanocomposites: preparation and properties of polyaniline (PAni)-coated bacterial cellulose nanofibers (BC)

Abstract

Free-standing films of bacterial cellulose (BC) and polyaniline (PAni) (BC/PAni) composites with high electrical conductivity values (0.9 S cm−1) and good mechanical properties (40 MPa) were prepared through in situ oxidative chemical polymerization of aniline (Ani) on the surface of synthesized BC nanofibers by using FeCl3·6H2O, as oxidant. The influence of polymerization conditions such as oxidant content, protonic acid, and reaction time on electrical conductivity, morphological, tensile properties and thermal stability of the BC/PAni composites was investigated. Electrical conductivities of BC/PAni composites increased with increasing reaction time due to the formation of a continuous layer that completely coated the nanofiber surface. FTIR spectra of BC/PAni composites produced with and without protonic acid exhibited overlapped absorption bands of both BC and PAni, except for quinoid and benzoid bending modes of PAni. The in situ oxidative chemical polymerization gives rise to conducting membranes with the surface constituted by different PAni content, as indicated through CHN elemental analysis. The crystalline structure of BC was not affected by the incorporation of PAni. Scanning electron microscopy analysis of the composites revealed that PAni consisted of nanoparticles around 70 nm in mean size to form a continuous coating that encapsulates the BC nanofibers. The BC/PAni composites obtained by the method described in this work have interesting properties that may find important technological applications such as sensors, electronic devices, intelligent clothes, flexible electrodes and tissue engineering scaffolds.