An easy two-step microwave assisted synthesis of SnO2/CNT hybrids

Tin oxide (SnO2) - decorated carbon nanotube (CNT) heterostructures were synthesized by microwave assisted wet impregnation method. CNTs of three different aspect ratios were compared. The hybrid samples were characterized by powder X-ray diffraction, Raman spectroscopy, high resolution transmission electron microscopy, BET surface area analysis and DC conductivity measurement. The results showed that the microwave assisted synthesis is a very efficient method in producing CNTs that are heavily decorated by SnO2 nanoparticles in a very short time (total reaction time of 10 min.), irrespective of their length and diameter. The hybrids showed 100 times increase in electrical conductivity when compared to the unmodified CNTs

Electrochemical and electrochromic properties of poly(4,4 dimethoxy 3'-methyl 2,2':5',2 terthiophene)

This work describes the electrochemical, spectroelectrochemical and electrochromic properties of poly(4,4 dimethoxy 3'-methyl 2,2':5',2 terthiophene) thin films. The effect of temperature on the electropolymerization was studied by cyclic voltammetry measured in situ. The temperatures used were -10, 0, 10, 20, and 40 ºC. Results indicate that the electropolymerization temperature directly affect the degree of chain organization. The optical response time for bleaching was 0.8 s and for coloring 0.3 s (for films synthesized at 40 ºC, 60 nm thick). After 1400 electrochromic cycles, the chromatic contrast at 570 nm changes from 31 to 14%. The coloration efficiency was enhanced as a function of redox cycling. This was probably caused by a decrease in the injected charge necessary for the color change, suggesting that the electroactive losses occurring during the cycles are related to sites not responsible for electrochromic contrast.Este trabalho descreve o estudo das propriedades eletroquímicas, espectroeletroquímicas e eletrocrômicas de filmes finos de poli(4,4 dimetoxi 3'-metil 2,2':5',2 tertiofeno). A voltametria cíclica in situ foi usada para estudar o efeito da temperatura sobre a eletropolimerização. As temperaturas utilizadas na deposição eletroquímica foram -10, 0, 10, 20 e 40 ºC. Os resultados indicaram que a temperatura de eletropolimerização afeta diretamente o grau de ordenamento molecular do polímero. O tempo de resposta eletrocrômico foi de 0,8 s para clareamento e 0,3 s para escurecimento (para filmes sintetizados a 40 ºC, espessura de 60 nm). Após 1400 ciclos eletrocrômicos, o contraste óptico a 570 nm diminuiu de 31 para 14%. A eficiência eletrocrômica foi intensificada em função do número de ciclos eletrocrômicos. Este fato foi provavelmente causado pela diminuição da carga injetada, necessária para a mudança de cor, sugerindo que as perdas na eletroatividade estão associadas a sítios que não são responsáveis pela mudança de coloração.733738Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Generating heat from conducting polypyrrole-coated PET fabrics

Heating effects in polypyrrole-coated polyethyleneterephthalate (PET)-Lycra&reg; fabrics were studied. Chemical synthesis was employed to coat the PET fabrics by polypyrrole using ferric chloride as oxidant and antraquinone- 2-sulfonic acid (AQSA) and naphthalene sulfonic acid (NSA) as dopants. The coated fabrics exhibited reasonable electrical stability, possessed high electrical conductivity, and were effective in heat generation. Surface resistance of polypyrrole-coated fabrics ranged from approximately 150 to 500 /square. Different connections between conductive fabrics and the power source were examined. When subjected to a constant voltage of 24 V, the current transmitted through the fabric decreased about 10% in 72 h. An increase in resistance of conductive fabrics subjected to constant voltage was observed<br /

Synthesis of anthraquinone based electroactive polymers: A critical review

Conducting polymers or synthetic monomers have revolutionized the world and are at the heart of scientific research having a scope of vast diverse applications in many technological fields. The conducting and redox polymers have been investigated as energy storage systems because of their better sustainability, ease of synthesis, and environmental compatibility. Owing to the conducting properties of quinones, they gain too much importance among the researchers. Keeping in view the importance and sustainability of conducting polymers, for the first time, this study compiles a detailed overview of synthetic approaches followed by investigations on electrochemical properties and future directions. This study critically examines the synthetic process of simple monomers, substituted monomers, and polymers of anthraquinone (AQ) under the classification of low- and high-molecular-weight AQ–based derivatives, their working principles, and their electrochemical applications, which enable us to explore their novel possible application in automotive, solar cell devices, aircraft aileron, and biomedical equipment. Irrefutably, we confirm that high-molecular-weight polymeric AQ compounds are best in comparison with low-molecular-weight AQ monomers because they have pre-eminent properties over monomeric systems. Because of the significant properties of AQ, polymeric systems are high demanding and have emerged as a hot topic among the researchers these days. In the current scenario, this study is of immense importance because it identifies and discusses the right and sustainable combination and paves the way to utilize these novel materials in different technologies

Using kahoot as a learning tool

The present work aims to investigate the use of kahoot as an educational resource in the teaching-learning process for high school students in the area of computer science. For this, an exploratory, descriptive and bibliographic approach was used. The research was carried out with 34 students of the technical course in computer science for internet of the Federal Institute of Goiás (FIG). The students performed the proposed activities and then answered a questionnaire using a GoogleDocs form. According to the results of the use of the platform, there was an improvement in students\u27 learning by reviewing and reinforcing the concepts learned in a fun, engaging, motivating and interesting way

Recent Advances in Conjugated Polymers for Light Emitting Devices

A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED) and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs) in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs) and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review