MATRIX EFFECT OF SECONDARY DOPING IN POLY ANILINE COMPOSITE

Secondary doping by m-cresol in polyaniline composite, which was prepa red by in situ emulsion polymerization technique and cast from solutio n, was studied by UV-Vis-NIR, ESR, WAXD and so on. The polyaniline con tent of the composite used in the present study is 11.0% (wt). After s econdary doping and then dedoping the composite showed a new absorbanc e at 580 similar to 800 nm, which directly demonstrated the increase o f conjugation length through expanding polyaniline backbone. The diffe rence of absorbance intensity at 600 similar to 800 nm implies that po lyaniline backbone can expand more completely in CSPE matrix than in S BS. The results from ESR in situ measurement show two kinds of interac tion between the carriers of conductive backbone: after secondary dopi ng, ESR intensity of PAn/CSPE markedly decreased and Delta H-pp kept c onstant, which indicates that secondary doping induce dipolaron: secon dary doping enhanced Delta H-pp of PAn/SBS from 3.0 X 10(-4) T to 5.6 X 10(-4) T but the intensity of ESR did not markedly change, which mea ns that secondary doping caused spin-spin interaction of polarons betw een conductive backbone. The results above can be explained by phase s tructure of composite caused by compatibility between polyaniline and matrix. It was found from WAXD of the composite after secondary doping that PAn/SBS had longer-range order crystal peak at 2.4 degrees (2 th eta) whereas PAn/CSPE had not. SEM was also taken for composites. The results supported the difference between two kinds of composite in pha se structure.