Study On Preparation And Performance Of Polypyrrole

With FeCl3as oxidant (n (FeCl3):n(pyrrole)=1:2), water and acetonitrile mixture as solvent, conductive polypyrrole (abbr. PPy) was prepared through pyrrole's oxidation polymerization in ice bath, and a series of PPy (marked as N-PPy) with different morphologies or particle size were obtained through changing volume ratio of acetonitrile to water (abbr. VRAW) in the mixed reaction solvents. The structures, morphologies, yield and conductivities of the as-prepared PPy were characterized by FT-IR, X-ray diffraction, SEM, Electronic Balance and Four-probe conductivity meter. The results of XRD show that N-PPy is semi-crystalline Polymer. Furthermore, the effect of VRAW on the morphology, yield and conductivity of N-PPy was investigated in detail. As shown from the corresponding results, PPy's average diameter decrease with the increase of VRAW in the range of1:9to4:6, with particle morphology; the film-shaped PPy is obtained when VRAW is in the scope of5:5to7:3. According to the analysis on the polymerization mechanism of pyrrole in the reaction mixture, the change of PPy's morphology is attributed to the structure change of acetonitrile micelle from spherical structure to double layered structure. As the further study shown, the PPy synthesized at a VRAW of1:9shows higher yield and conductivity than which prepared in pure water without acetonitrile. However, the further increase of VRAW results in the decrease of the yield and conductivity. N-PPy has good thermal stability and their thermal decomposition temperature is about200℃.The H-seriy of PPy (marked as H-PPy) with semi-crystalline structure were obtained by increasing the monomer molar ratio of FeCl3to pyrrole (n(FeCl3):n(pyrrole)=1:1). As shown from the corresponding results, with the increase of VRAW in the range of0:10to7:3, the morphologies of H-PPy show a similar change rule as that of N-PPy. It suggests that the increase of oxidant content don't change the variation rule. Also to be found that H-PPy has higher yield and lower conductivities than N-PPy as VRAW is same.By increasing the reaction temperature, the T-seriy of PPy (marked as T-PPy) with semi-crystalline structure were obtained. The results indicat that T-PPy has higher yield than N-PPy and little morphology changes with granular structure when VRAW in the range of1:9to7:3. Compared with N-PPy, T-PPy has markedly different morphology variation. It shows that the higher reaction temperature has destroyed the acetonitrile micelle and changed the variation rule about the effect of VRAW on T-PPy's morphology. When VRAW is in the range of0:10to2:8, T-PPy has the higher conductivities compared with N-PPy. But T-PPy's conductivity is lower than N-PPy's when VRAW was4:6.The S-seriy of PPy (marked as S-PPy) with semi-crystalline structure were obtained by adding SDBS in reaction system. And the results indicate that PPy's morphology become more regular with the increase of VRAW in the range of1:9to4:6. When VRAW is in the range of3:7to5:5, the PPy products show particle-shaped morphology and PPy's average diameter decrease with the increase of VRAW. When VRAW is up to6:4, there is flake-shaped morphology in products and the particle-shaped PPy's average diameter increases. Compared with N-PPy, S-PPy had markedly different morphology variation. It shows that the added SDBS has changed the variation rule about the effect of VRAW on PPy's morphology. The investigation also shows that the yield of PPY decreas with the increase of VRAW in the range of0:10to6:4and S-PPy has higher yield than N-PPy as VRAW is same. The investigation also demonstrates that the conductivity of PPY increase with the increase of VRAW in the range of0:10to2:8, and decrease with the further increase of VRAW in the scope of2:8to6:4. When VRAW is in the range of0:10to2:8, S-PPy has the lower conductivities compared with N-PPy. But S-PPy's conductivities were higher than N-PPy's with the further increase of VRAW in the scope of2:8to6:4.