In this work, the structural characteristics and DC electrical conductivity of firstly synthesized organic–inorganic nanocomposites of thermoelectric Te0 nanoparticles (1.4, 2.8, 4.3 wt%) and poly(1-vinyl-1,2,4-triazole) (PVT) were analyzed. The composites were characterized by high-resolution transmission electron microscopy, X-ray diffractometry, UV-Vis spectroscopy, and dynamic light scattering analysis. The study results showed that the nanocomposite nanoparticles distributed in the polymer matrix had a shape close to spherical and an average size of 4–18 nm. The average size of the nanoparticles was determined using the Brus model relation. The optical band gap applied in the model was determined on the basis of UV-Vis data by the Tauc method and the 10% absorption method. The values obtained varied between 2.9 and 5.1 nm. These values are in good agreement with the values of the nanoparticle size, which are typical for their fractions presented in the nanocomposite. The characteristic sizes of the nanoparticles in the fractions obtained from the Pesika size distribution data were 4.6, 4.9, and 5.0 nm for the nanocomposites with percentages of 1.4, 2.8, and 4.3%, respectively. The DC electrical conductivity of the nanocomposites was measured by a two-probe method in the temperature range of 25–80 °C. It was found that the formation of an inorganic nanophase in the PVT polymer as well as an increase in the average size of nanoparticles led to an increase in the DC conductivity over the entire temperature range. The results revealed that the DC electrical conductivity of nanocomposites with a Tellurium content of 2.8, 4.3 wt% at 80 °C becomes higher than the conventional boundary of 10−10 S/cm separating dielectrics and semiconductors.
2Иркутский институт химии им. А.Е. Фаворского СО РАН, 670033, Россия, г. Иркутск, ул. Фаворского, 1 3 Иркутский национальный исследовательский технический университет, 664074, Россия, г. Иркутск, ул. Лермонтова, 83Аннотация В данной статье приводится обзор работ, посвященных химическому синтезу и исследованию характеристик металлополимерных нанокомпозитов с полисахаридными матрицами и наночастицами золота и серебра сферической формы. При отборе статей предпочтение отдавали работам, в которых для создания нанокомпозитов использовали in situ синтез химическим восстановлением прекурсоров металлов. Уделено внимание явлению поверхностного плазмонного резонанса и связанным с ним теоретическим моделям, приводятся сведения по экспериментально полученному оптическому поглощению нанокомпозитов.Ключевые слова: нанокомпозит, полисахаридная матрица, наночастицы золота и серебра, оптическое поглощение, поверхностный плазмонный резонанс. AbstractThis paper is a review of the articles devoted to chemical synthesis and characterization research of metallopolymer nanocomposites with polysaccharide matrices and sphere-shaped Au and Ag nanoparticles. During the paper selection preferences have been given to the works that reported on nanocomposite preparation with in situ synthesis and chemical reduction of metal precursor. Special attention was paid to Surface Plasmonic Resonance phenomenon and theoretical models related to it. Experimental data on optical absorption investigations of nanocomposites are presented. ВведениеНаночастицы золота и серебра человек давно использовал в медицине (питьевое золото), строительстве (витражное стекло), произведениях искусства (кубок Ликурга). Научное описание оптических свойств наноразмерного металла началось со второй половины XIX в. В настоящее время изучению методов создания и исследованию химических, физико-химических, физических, биологических свойств структур, содержащих наночастицы золота и серебра, посвящено множество научных работ. Данное направление активно разрабатывается, не теряет своей актуальности.Использование наносеребра в медицине, косметологии, фармацевтике обеспечивается его бактерицидным, противовирусным, противогрибковым свойствами. Наночастицы серебра применяют в сенсорах химических веществ и в каталитических системах, в электроникев составе электропроводящих паст и клеев. В медицине и биотехнологии наночастицы золота и серебра используются для создания биосенсоров, а также для формирования биоконъюгатов с пептидами, липидами, энзимами, которые используются в препаратах для направленной доставки лекарств [1].С технологической точки зрения выгодно решить задачу создания объекта с определенной морфологией. Поскольку в нанотехнологии размер нанообъекта влияет на проявляемые им свойства, важно научиться создавать монодисперсные объекты однообразной формы с равномерным пространственным распределением в некоторой среде. Высокая поверхностная энергия наночастиц делает их экстремально реактивными [2]. Наночастицы не стабильны, стремятся к агрегированию или агломерации. Возможны эл...
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.
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