The Optimal Sulfonation Conditions of Self-doped Polyaniline Obtained by Using Experimental Strategies

The optimal sulfonation condition of self-doped sulfonated polyaniline(prepared from leucoemeraldinebase;denoted as LEB-SPANI) with a high electronic conductivity was obtained by experimental strategies,includingthe fractional factorial design(FFD) and central composite design(CCD).From the FFD experiment,the self-doped LEB-SPANI prepared at a lowtemperature(4oC),a short reaction time(1 h),and a small volume of fumingsulfuric acid(10 mL) showed a better conductivity(ca.127 mS/cm).In the CCD study coupled with a confirmationtest,the highest conductivity(ca.141 mS/cm) of the LEB-SPANI film was obtained under a sulfonation temperatureof 4oC,a sulfonation time of75 minutes,and a volume of8 mLof30% fuming sulfuric acid.The textural cha-racter-istics of self-doped LEB-SPANI were characterized by Fourier transform infrared(FTIR) spectroscopy,four-pointprobe method,and X-ray photoelectron spectroscopy(XPS).The sulfonation rate and degree of LEB-SPANI werefound to be dependent upon the acid used in the polymerization step of PANI.