The influence of polymerization temperature on structure and properties of polyaniline

Abstract

Abstract:The influence of polymerization temperature (from -25 to +25 o C) on molecular weight, crystallinity, electrical conductivity, thermal and morphological properties of polyaniline has been investigated. Aniline was oxidized in an aqueous medium with ammonium persulfate and 1.0 M hydrochloric acid. The reaction mixture freezes below -10 o C and hence lithium chloride was used in sufficient amount to prevent freezing. As the reaction temperature decreases, both the molecular weight of polyaniline and its crystallinity increase. Thermal studies show a common three step decomposition pattern irrespective of the temperature used during synthesis. The morphology of polyaniline changes from granular (reaction in liquid medium) to tubular (polymerization in the frozen state). Thermal analysis indicated that the polyaniline stability increased with decreasing synthesis temperatures. Electrical conductivity of polyaniline was found to be independent of the polymerization temperature and, consequently, of the molecular weight.

Spectroscopic and Structural Properties of Dopant Functionalized Polyaniline Prepared in a One-Step Procedure

“…This result is probably due to the characteristics of the reactional medium and especially to the pKa value (pKa (NDSA) = −0.6). Generally, the elementary analyses results carried out on the polyaniline; prove the presence the oxygen in the formula composition and this attendance due to bound water molecules (25,26). In our product; a substantial degree of hydration is round 0.8 molecule of water per repeat unit.…”

One pot synthesis of ureas and carbamates via oxidative carbonylation of aniline-type substrates by CO/O2 mixture catalyzed by Pd-complexes

“…Polyaniline was identified on the basis of elemental analysis% (exp./calc. ): C (79.82/78.26), H (5.48/6.52), N (15,06/15,22), IR: 3419 cm −1 , 1448 cm −1 , 1398 cm −1 , 1261 cm −1 , 1091 cm −1 -the bands characteristic for the polymer chain [34,35], UV-vis: band ( max = 286 nm) corresponding to → * transition (there was no n → * band observed and it means that totally reduced form of polyaniline was obtained [34]), and 1 H NMR: characteristic for polyaniline multiplet in the range of 6.5-7.5 ppm, being consistent with the literature data [36,37]. Analysis of the liquid phase was performed by the use of gas and liquid chromatography (GC-FID, GC-MS and HPLC).…”

Synthesis and Conductivity Studies of Poly(Methyl Methacrylate) (PMMA) by Co-Polymerization and Blending with Polyaniline (PANi)

“…It was found that high molecular weight and crystallinity of PANi were due to the low polymerization temperature used during the synthesis process [103]. However, it was also reported by Yilmaz et al ( 2009) that the polymerization temperature has no significant effect on the conductivity of PANi [103]. However, contradictory findings were reported by the other researchers that demonstrated that the conductivity of PANi increased with the decreased polymerization temperature [104,105].…”

“…There have been several studies that reported the influences of polymerization temperature on the molecular weight and conductivity of PANi [99][100][101][102]. It was found that high molecular weight and crystallinity of PANi were due to the low polymerization temperature used during the synthesis process [103]. However, it was also reported by Yilmaz et al ( 2009) that the polymerization temperature has no significant effect on the conductivity of PANi [103].…”