Synthesis and characterization of polyaniline/tosylcellulose stearate composites as promising semiconducting materials

Abstract

Tosylcellulose stearate (TCSt) as a thermoplastic polymer has been prepared starting from microcrystalline cellulose (MCC) which was converted into a more reactive and solvent soluble tosylcellulose (TC) with degree of substitution = 0.45 under homogenous conditions. Then, tosylcellulose underwent esterification reaction through its reaction with stearic anhydride in DMF/DCM to afford tosylcellulose stearate. FT-IR, 13C NMR, and elemental analyses confirmed the chemical structure of both tosylcellulose and tosylcellulose stearate. TCSt fibers were used as matrix for polyaniline (PANI) which had been prepared via in situ oxidative polymerization of aniline hydrochloride using hydrochloric acid as dopant and ammonium persulfate as an oxidizing agent. PANI/TCSt composites with loading ratios of 75:25, 50:50, and 25:75 wt/wt were fabricated. The thermal stability, degree of crystallinity, and surface morphology of the prepared composites were characterized. The presence of PANI improved the thermal stability of the PANI/TCSt composites with (50:50 wt:wt). The electrical conductivity for PANI/TCSt composites was measured by Broadband Dielectric Spectrometer, and the conductivity values of PANI/TCSt composite prepared at weight ratio 75:25 wt% was coincided with those of PANI alone. Increasing the temperature from −40 to +50 °C increased the conductivity of the composites by about two orders of magnitudes for all investigated samples. The films prepared from TCSt and PANI/TCSt composite (50:50 wt:wt) displayed improved mechanical properties when compared with the films prepared from cellulose acetate (CA) and CA/PANI composite (50:50 wt:wt).