No abstract

No abstract

Electron localization in the methyl ring-substituted derivative of polyaniline, poly(o-toluidine), has been investigated by electric field dependence of conductivity u(E). We found /nu(,!?) = K P , with K varying as square root of temperature (K c* ,-I/*). This result is in accord with quasi-one-dimensional variable range hopping of charge carriers localized along a one-dimensional chain, with an effective Coulomb barrier between adjacent sites. The measured non-ohmic conductivity is modeled by the Poole-Frenkel effect where the Coulomb potential between localized sites is lowered by the electric field. Model analysis yields an estimated effective barrier height of -0.1 eV, corresponding to an effective charge carrier mass of the order of that of an electron. In contrast, the charging energy limited tunneling model predicts Inu E -I , which is not consistent with the experimental results.

We report optical, thermal, and transport studies on Kr+ implanted ladder (BBL) and rigid-rod ( PBO and PBZT) polymers, with an ion energy of 200 keV and dosage of 4 × 1016 / cm2. Both pristine and ion implanted polymers were studied using X-ray photo-electron spectroscopy (XPS), optical spectroscopy (IR and UV-Vis), thermogravimetric analysis (TGA), and temperature dependent DC conductivity (σ(T)). The XPS and IR results show a reduction in the heteroatoms and increase in the relative carbon content. After ion implantation, each polymer had a similar electronic structure, showing broad band metallic behavior. TGA data shows that each implanted polymer retains its thermal stability. σ(T) of the implanted polymers has the weakest temperature dependence of any conducting polymer reported, in accord with a disordered metal.