Naslov
Electromagnetic properties of DBSA-doped polyaniline: from fundamentals towards application with carbon nanotubes

Autori
Mirko Baćani, Ivan Kokanović, Mario Novak, Dinko Babić

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
From Basic to Life Sciences 7 / - , 2014

Skup
From Solid State to Biophysics VII

Mjesto i datum
Dubrovnik, Hrvatska; Cavtat, Hrvatska, 07.06.2014. - 14.06.2014

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Polyaniline; carbon nanotubes

Sažetak
We have carried out a comparative experimental study of the dc electrical conductivity σ and magnetic susceptibility χ of own-made polyaniline (PANI) pellets doped with dodecybenzenesulphonic acid (DBSA), a long molecule with surfactant properties. For all the samples, we find [1] that σ at low temperatures (T) is governed by the variable- range hopping (VRH) in a homogeneously disordered three-dimensional (3D) system of coupled one-dimensional (1D) chains. Depending on the doping and the corresponding disorder level, the VRH exponents are either 1/2, 2/5, or 1/4. At higher T, in all the samples, we find the exponent 1 that signifies nearest- neighbour hopping. All these exponents are predicted in a model by Fogler, Teber, and Shklovskii [2] for the charge transport in quasi-1D Anderson-Mott insulators, and conditions for their appearance depend on disorder and T. We identified the presence of a soft (Coulomb) gap in our samples, which signifies a long-range Coulomb interaction. Changes from one exponent into another in σ appear at crossover temperatures T*, where there are also noticeable features in χ(T). This coupling of charge and spin is discussed in the spirit of kBT* being the thermal energy which causes an enhancement of the density of delocalised (Pauli) spins at the expense of localised (Curie) spins as T rises above T*. Utilising a property that both PANI-DBSA and multiwall carbon nanotubes (MWCNT) are soluble in chloroform, we have produced bulk blends of these two materials, the achieved mass fraction of MWCNT being up to 40 %. This is as remarkable as the accompanying effective loss of the temperature dependence of σ: it decreases by only 3 times from room temperature to 10 K, whereas this decrease for pure PANI- DBSA is by a factor of 106. Thus, our blends simultaneously offer a solution to a problem of application of MWCNT in bulk form, as well as to that of the poor conductivity of PANI-DBSA at low T. It is also possible to make thin films, both of PANI-DBSA and of the blends, on a commercial plastic substrate (FR4). [1] M. Baćani, M. Novak, I. Kokanović, D. Babić, Synth. Met. 172, 28 (2013) [2] M. M. Fogler, S. Teber, B. I. Shklovskii, Phys. Rev. B 69, 035413 (2004)

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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