Multifunctional hybrid films from sudan III and multiwalled carbon nanotubes: electrical conduction and photoinduced molecular orientation

Abstract

Multifunctional materials (MFMs) can be an important system because of their capacity to combine different properties useful for electronic devices. Multiwalled carbon nanotubes (MWCNTs) and azobenzene derivate Sudan III (SIII) are compounds with great potential to form this type of system. These compounds exhibit properties of electrical conduction and photoinduced molecular orientation, respectively, which can be combined in a single film-shaped system. In this study, we report on the fabrication and characterization of multifunctional hybrid films created from SIII mixed with MWCNTs via both Langmuir and Langmuir–Blodgett (LB) techniques. For SIII+MWCNTs monolayers obtained using the Langmuir technique, the surface pressure isotherms revealed that the aggregation process of pure SIII drives the formation of monolayers. Brewster angle microscopy of the monolayers indicated that MWCNTs form loop-shaped structures resembling rings. Such structures were not present in films of pure MWCNTs or pure SIII. The current–voltage characteristic curve showed that the films have an ohmic behavior associated to free electrons in MWCNTs, exhibiting conductivity on the order of that of semiconductors. The SIII+MWCNTs LB films exhibited a photoinduced molecular orientation determined via SIII photoisomerization. These processes, occurring in a single film, are the conceptual proof that these systems are MFMs with potential applications in developing hybrid devices.