Mechanochemical Synthesis and DC Electrical Conductivity of PANI-Based MWCNT Containing Nanocomposites with Te⁰ and Bi₂Te₃ Thermoelectric Nanophase

Nowadays, the search for the coupled polymer nanocomposite thermoelectrics that exhibit a high value of thermoelectric figure of merit (ZT) and similar behaviour of physical properties for the use as legs of thermoelectric cells is a current challenge. The direct current (DC) conductivity is one of the three important components of thermoelectric figure of merit. The aim of this study was to obtain PANI-based nanothermoelectrics with Te0 and Bi2Te3 nanoparticles and MWCNT by mechanochemical methodology and to investigate the dependency of their DC electrical conductivity on temperature in the 298–353 K range using the Arrhenius and Mott’s variable range hopping (VRH) models. Inorganic Te0 and Bi2Te3 nanoparticles were pre-synthesized by the available and environmentally friendly method using a commercial tellurium powder. The samples obtained were characterized by X-ray diffractometry (XRD), IR and UV-Vis spectroscopy. The XRD study of ES-PANI/Te0 (4.4 wt% Te0) and ES-PANI/Bi2Te3 (2.9 wt% Bi2Te3) nanocomposites found that the nanoparticle average size was 32 nm and 17 nm, respectively. The DC conductivity study of the samples with different nanophase content (2.1, 4.4, 10.2 wt% Te0, 1.5, 2.9, 7.3 wt% Bi2Te3, 1.5 wt% MWCNT) by the two points measurement method reveals the following: (a) the presence of inorganic nanophase reduces the conductivity compared to the matrix, (b) the addition of MWCNT in ES-PANI increases its electrical conductivity, (c) the conductivity of ES-PANI/Te0 as well as ES-PANI/Bi2Te3 nanocomposite rises with the increasing inorganic nanophase content, (d) the observed increase in the electrical conductivity of MWCNT-based nanocomposites with increasing inorganic nanophase content is interrupted by a characteristic area of decrease in its value at average values of inorganic nanoparticles content (at Te0 content of 4.4 wt%, at Bi2Te3 content of 2.9 wt%), (e) a similar DC conductivity behaviour in ES-PANI/Te0—ES-PANI/Bi2Te3 and ES-PANI/Te0-MWCNT—ES-PANI/Bi2Te3-MWCNT nanocomposite pairs is observed

Эволюция оптического поглощения нанокомпозитов серебра с сополимерной матрицей арабиногалактан-олигопиррол

The optical absorption spectra measured of radically new nanocomposite of silver nanoparticles and arabinogalactan-g-oligopyrrole block-copolymer have 3 optical bands at 294, 426 and 585 nm. There have been no absorption maxima shifts but only absorption intensity decrease of the first and the sec- ond optical bands during eight months. Reduction of optical absorption intensity at 294 nm is related to decrease of acyl radical quantity in the nanocomposite. Decrease of 0D and 1D nanosilver plasmon absorption intensity at 426 nm can be explained by increase of the nanoparticle size in consequent to nanoparticle coalescence. Optical absorption of nanocomposite at 585 nm is associated with longitudal component of 1D nanosilver plasmon resonance and presence of plasmons in the oligopyrrole chains.В спектрах оптического поглощения принципиально нового нанокомпозита серебра с привитым блок-сополимером арабиногалактан-олигопиррол, для которого характерны полосы поглощения при 294, 426, 585 нм, в течение восьми месяцев наблюдали снижение интенсивности погло- щения первых двух максимумов поглощения. Убывание интенсивности при 294 нм объясняет- ся уменьшением количества ацильных радикалов, возникающих в арабиногалактане при синтезе нанокомпозита. Снижение интенсивности плазмонного поглощения при 426 нм 0D- и 1D-наносеребра, возможно, связано с укрупнением частиц за счет их коалесценции. Оптическое поглощение нанокомпозита при 585 нм обусловлено продольной компонентой плазмонного резонанса 1D-наносеребра и наличием поляронов в олигопиррольных ветвя

Эволюция оптического поглощения нанокомпозитов серебра с сополимерной матрицей арабиногалактан-олигопиррол

The optical absorption spectra measured of radically new nanocomposite of silver nanoparticles and arabinogalactan-g-oligopyrrole block-copolymer have 3 optical bands at 294, 426 and 585 nm. There have been no absorption maxima shifts but only absorption intensity decrease of the first and the sec- ond optical bands during eight months. Reduction of optical absorption intensity at 294 nm is related to decrease of acyl radical quantity in the nanocomposite. Decrease of 0D and 1D nanosilver plasmon absorption intensity at 426 nm can be explained by increase of the nanoparticle size in consequent to nanoparticle coalescence. Optical absorption of nanocomposite at 585 nm is associated with longitudal component of 1D nanosilver plasmon resonance and presence of plasmons in the oligopyrrole chains.В спектрах оптического поглощения принципиально нового нанокомпозита серебра с привитым блок-сополимером арабиногалактан-олигопиррол, для которого характерны полосы поглощения при 294, 426, 585 нм, в течение восьми месяцев наблюдали снижение интенсивности погло- щения первых двух максимумов поглощения. Убывание интенсивности при 294 нм объясняет- ся уменьшением количества ацильных радикалов, возникающих в арабиногалактане при синтезе нанокомпозита. Снижение интенсивности плазмонного поглощения при 426 нм 0D- и 1D-наносеребра, возможно, связано с укрупнением частиц за счет их коалесценции. Оптическое поглощение нанокомпозита при 585 нм обусловлено продольной компонентой плазмонного резонанса 1D-наносеребра и наличием поляронов в олигопиррольных ветвя