PVK/MWNT Electrodeposited Conjugated Polymer Network Nanocomposite Films

The facile preparation of poly (N-vinyl carbazole) (PVK) and multiwalled carbon nanotubes (MWNTs) solution and conjugated polymer network (CPN) nanocomposite film is described. The stable solutions of PVK/MWNT were prepared in mixed solvents by simple sonication method, which enabled successful deaggregation of the MWNTs with the polymer matrix. MWNT was most effectively dissolved in N-cyclohexyl-2-pyrrolidone (CHP) compared to other solvents like N-methyl pyrrolidone (NMP), dimethyl formamide, and dimethyl sulfoxide (DMSO). The composite solution was relatively stable for months with no observable precipitation of the MWNTs. Thermogravimmetric analysis (TGA) revealed the thermal stability of the nanocomposite while the differential scanning calorimetry (DSC) showed an increasing melting (T(m)) and glass transition (T(g)) temperatures as the fraction of the MWNTs in the nanocomposite was increased. Cyclic voltammetry (CV) allowed the electrodeposition of the nanocomposite film on indium tin oxide (ITO) substrates and subsequent cross-linking of the carbazole pendant group of the PVK to form CPN films. Ultraviolet-visible (UV-vis), fluorescence, and Fourier transform infrared (FTIR) confirmed film composition while atomic force microscopy (AFM) revealed its surface morphology. Four-point probe measurements revealed an increase in the electrical conductivity of the CPN nanocomposite film as the composition of the MWNTs was increased: 5.53 × 10(-4) (3% MWNTs), 0.53 (5%), and 1.79 S cm(-1) (7%). Finally, the interfacial charge transfer resistance and ion transport on the CPN nanocomposite film was analyzed by electrochemical impedance spectroscopy (EIS) with a measured real impedance value of ∼48.10 Ω for the 97% PVK and 3% MWNT ratio of the CPN nanocomposite film.