ABSTRACT
Conducting polymers because of their electronic, magnetic, and optical properties are an attractive class of materials for variety of advanced technologies [1-5]. Among conducting polymers, polyaniline (PANI) has been extensively studied due to its good environmental stability, electrical properties and inexpensive monomer. Some of potential applications of PANI are:
As component of electrochemical batteries [6, 7]; as chemical sensors in solution [8-10]; optical wave guides [11]; microelectronic devices [12, 13]; to produce electrochromic devices [14]; as antioxidant for rubbers and plastics [15, 16]; to produce conductive rubber and plastics composites [17, 18]; catalyst for chemical reaction [19]; a component in gassensing devices for the “electronic nose” [10, 20, 21]; as antistatic coating and electromagnetic shielding material [22, 23]; and etc. Substituted PANI is of great interest for variety of applications as above mentioned for PANI. There has been considerable interest in developing new synthetic approaches for their production. Substituted PANI with altered properties can be made by adding functional groups to the backbone of the polymer. Ring substituted of alkyl PANI [24, 25]; and alkoxy (ethoxy, methoxy) ring substituted PANI [26, 27]; strong electron withdrawing groups (–CF3, –CN, –NO2) ring substituted PANI [28], Ring substituted polymerization of o-toluidine, m-toluidine and o-chloroaniline was reported by Sazou [29]. Ring substituted PANI was also obtained by coupling of 4-sulfobenzene diazonium ion and poly (N-methylaniline) [30]. A typical synthesis of substituted polymer may be carried out via oxidative polymerization of the corresponding monomer [31]. In many cases the substituted monomer with desired functional group is either too diffi cult to oxidize or sensitive to oxidative or acidic conditions. A new synthetic strategy was developed by Freund [32] to obtain ring substituted poly(hydroxyaniline) and poly(iodoaniline), using poly (aniline boronic acid) as a precursor for substitution. Herein, we report the synthesis of propylthiol ring substituted PANI by reaction of 3-chloropropylthiol and ferric chloride with dimethylsulfoxide solution of emeraldine base form of PANI. The 3-chloropropylthiol ring substitution of PANI was also carried out on the surface glassy carbon electrode.
