International audienceNanostructured semiconducting oxides have been used as resistive gas sensors of toxic and non-toxic gases, but little emphasis has been placed on ozone sensing. Here we present a new ozone gas sensor based on hierarchical NiCo2O4 cubic structures synthesized via a facile urea-assisted co-precipitation method and annealed at 450 degrees C, which showed a low detection level. Ozone detection was carried out through electrical measurements with an optimized performance at 200 degrees C, with fast response (similar to 32 s) and recovery (similar to 60 s) time with suitable concentration range (from 28 to 165 ppb) for technological applications. Furthermore, NiCO2O4 platelets are selective to ozone compared to other oxidizing and reducing gases. The low detection level can be attributed to the coexistence of 3D structures based on hexagonal platelet-like and porous flower-like shape, which were revealed by field emission scanning electron microscopy (FE-SEM). In summary, NiCo2O4 is promising for detection of sub-ppb levels of ozone gas

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Synthesis of a polyfluorene/poly(p-phenylene vinylene) derivative, the Poly [(9,9 0 -di-hexylfluorenediylvinylene-alt-1,4-phenylenevinylene)-co-((9,9 0 -(3-t-butylpropanoate) fluorene-1,4-phenylene)] (LaPPS 42) was performed following Wittig and Suzuki routes. Polyfluorenes and derivatives have been used in electroluminescent devices, and the synthesis described here has the advantage in pave the way to get distinct structures having different emission spectra. An extensive study of its electrochemical, thermomechanical, optical, and structural properties was carried out, as well as its application in electroluminescent devices. Polymer light-emitting diodes (PLEDs) and polymer light-emitting electrochemical cells (PLECs) were built using LaPPS 42 as active layer, and their electric and optical characterizations confirm they have a potential as active element in electroluminescent devices.

Many pathways can be used to synthesize polythiophenes derivatives. The polycondensation reactions performed with organometallics are preferred since they lead to regioregular polymers (with high content of heat-to-tail coupling) which have enhanced conductivity and luminescence. However, these pathways have several steps; the reactants are highly moisture sensitive and expensive. On the other hand, the oxidative polymerization using FeCl 3 is a one-pot reaction that requires less moisture sensitive reactants with lower cost, although the most common reaction conditions lead to polymers with low regioregularity. Here, we report that by changing the reaction conditions, such as FeCl 3 addition rate and reaction temperature, poly-3-octylthiophenes with different the regioregularities can be obtained, reaching about 80% of heat-to-tail coupling. Different molar mass distributions and polydispersivities were obtained. The preliminary results suggest that the oxidative polymerization process could be improved to yield polythiophenes with higher regioregularity degree and narrower molar mass distributions by just setting some reaction conditions. We also verified that it is possible to solvent extract part of the lower regioregular fraction of the polymer further improving the regioregularity degree.

Three-dimensional microstructures with selective properties have often been developed for optical and photonic applications. The simplest way to achieve optically active structures is by the functionalization of host matrices using, for instance, organic dyes. Laser fabrication techniques, such as two-photon polymerization, allow manufacturing devices quickly, with high resolution, without shape limitation, among other many advantages. In this work, we demonstrate the fabrication of three-dimensional microstructures via two-photon polymerization, using azobenzene-based dyes as photoinitiator, the compound responsible for absorbing the light and start the polymerization. When a high photoinitiator concentration is used (for instance 1.00 wt%), a significant amount of dye remains unchanged into the final structures, and its optically induced birefringence could be investigated. Therefore, the azobenzene-based dye acts, at the same time, as the photoinitiator and functionalizer.

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Tem experiência na área de Física, com ênfase em Física e espectroscopia óptica, atuando principalmente nos seguintes temas: vidros, nanocristais, nanofibras, co-dopados, Terras Raras e desenvolvimento e aprimoramento sensores. Também lecionou como docente na UFSCar pelo Departamento de Física (2018-2020). Atualmente, Fundadora da Idelma Terra Educação e Desenvolvimento Pessoal ênfase em comunicação e oratória, atua com treinamento e consultoria, especializada em graduados e pós-graduandos. São Carlos-SP.