Physico-chemical studies on conducting polymers

Abstract

'I1H~eJemental analysis of polyaniline synthesized in this study support.~ the empcrical fonnula of polyaniJinc as : (C.H.NH). 2 HSO•. The mechanism of polymerisalion inf•n...cd that one anion (HSa•.') is substituled tilT every two phenyl rings. In the infrared spectra of polyaniline, a strong absorption band at around 48U em-'. gives an evidence of I, 2, 4. substituted arorn"tic ring. This indicates the bonding in polymer is through I, 4- positioll ofbcllzcnc ring. From the scanning electron micrograph of polyaniline at 25QC and al it currell! density of SmA/em 2 exhibits grain like morpllOJogy. The average bundle size oftlle grail1SofpolyaniJinc incre:u>cswith the increase of current density. Also, with the change of pol)mcrization temperature there is 11 dramatic change in morphology of POlyullilinc. The grains take microspherical morphology lor polyalliline prepared at 25°C temperature have heen ehanged to a fibrillar one when S)llthesis is carried out at 9°C. 111e electrical l:onductivities of both the polymers (polyaniline ami poly o-toluidine) s)'nthesiled at diftcrenct temperature and diflercnt current density increases with the decrease of temperature and the maximum eondictivity is ()bserved at 9°C. The highest e1e<,.1rical oonductivity is also ohserved in bolh the polymer prepared at the ,",urrentdensity of 10 nuVcm2. In the case of uv-visible spectra of the polymers syntheskd at 11 curren! density of LOnvVcm2 sho••'.s••tJle smaller band gap energy tJJan Ulal sYIlthesized at 5 and 15 ,rnA/em'. It is also observed that the absorption band appears always at low~'renergy in the easo of polyaniline tJl:tn that of poly o-toluidine, In the X-ray diffraction patterns, the peaks arc broad and diffused for thc polymen; synthesized at .5 mAfem2. The peaks become sharper as dcpo~itioll current density increases. In case of poly o-toluidine the existance of the broad diffuse peak indicates amoITJhousnature deposited at room temperature and eurrenl densiIy ranging from 5 toI5 rnA/em'. It is also found for bot1l for polyaniJine and poly o-tolll1dine, that lower deposition temperature results in sharper of dim-adion peaks suggesting more crystallinity. Although in case of polyaniline, increased deJlQsition eurrenl density increased crystallinity, this is not so evident for poly 0- toluidine.......................................................................................