Desenvolvimento de filmes finos poliméricos para aplicação em dispositivos fotovoltaicos orgânicos

Exportado OPUSMade available in DSpace on 2019-08-13T17:12:56Z (GMT). No. of bitstreams: 1 dissertacao_glendarbslacerda.pdf: 4173090 bytes, checksum: 3ba19bdfb4aaf3be95640ff618992872 (MD5) Previous issue date: 31Este trabalho apresenta o estudo de polímeros e copolímeros conjugados derivados do tiofeno com propriedades promissoras para aplicação em células fotovoltaicas orgânicas (OPV). Inicialmente realizou-se a síntese do monômero 3-(4-fluorfenil)tiofeno (FFT), bem como sua caracterização empregando técnicas como espectroscopia na região do infravermelho (IV), espectroscopia de ressonância magnética nuclear de próton (RMN de 1 H) e de carbono 13 (RMN de 13 C) e cromatografia gasosa acoplada à espectrometria de massa (CG-MS) comprovando assim a obtenção da estrutura pretendida. Em uma etapa seguinte, partindo-se do FFT sintetizado e de monômeros comerciais e empregando-se a cronoamperometria, obteve-se os polímeros: o poli(3-(4-fluorfenil)tiofeno) (PFFT), poli(3,4-etilenodioxitiofeno) (PEDOT) e o poli(3-feniltiofeno) (P3FT) e também os copolímeros poli(3,4-etilenodioxitiofeno-co-3-feniltiofeno) (P(EDOT-co-3FT)) e poli(3,4-etilenodioxitiofeno-co-3-4-fluorfeniltiofeno) (P(EDOT-co-FFT)). Os polímeros e copolímeros foram caracterizados com sucesso utilizando técnicas de IV, absorção na região do UV-vis e fluorescência, termogravimetria (TG) e microscopia eletrônica de varredura (MEV). Observou-se que a inserção do monômero EDOT para a formação dos copolímeros contribui para aestabilização das cargas, sendo o P(EDOT-co-3FT) o material mais estável eletroquimicamente e com menor perda de carga sob ciclagem eletroquímica. Todas as amostras tiveram seu comportamento espectroeletroquímico estudado e observou-se que os copolímeros apresentaram potencial para aplicação em OPVs. A variação de cor entre o estado reduzido e oxidado também foi observada, sendo que o PEDOT variou do azul para azul escuro, o P3FT do cinza para vermelho e PFFT do cinza para vermelho. Já os copolímeros P(EDOT-co-3FT) variaram do azul para roxo e o P(EDOT-co-FFT) do azul escuro para o roxo escuro. A cronoabsormetria permitiu determinar parâmetros importantes para aplicação em dispositivos eletrocrômicos como eficiência eletrocrômica (), contraste óptico (%T) e tempo de resposta ().This work presents the study of conjugated polymers and copolymers derivative from thiophenes, with promising properties to organic photovoltaic cells application (OPV). Initially, was realized the synthesis of the monomer 3-(4- fluorophenyl)thiophene (FFT), as well its characterization employing techniques as spectroscopy in infrared range( IV), resonance spectroscopy nuclear of protons (RMN of 1 H) and carbon 13 (RMN of 13 C), and gas chromatography coupled to mass spectroscopy (CG-MS) proving that the intended structure was obtained. In the next step, taking the synthesized FFT along commercial monomers and employing the chronoamperometry, the following polymers was obtained: the poly(3-(4-fluorophenyl)thiophene) (PFFT), poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3-phenylthiophene) (P3FT). Using the same process, two copolymers was obtained as well: the poly(3,4-ethylenedioxythiophene-co-3-phenylthiophene) (P(EDOT-co-3FT)) and poly(3,4-ethylenedioxythiophene-co-3-(4-fluorophenyl)thiophene) (P(EDOT-co-FFT)). The polymers and copolymers were successfully characterized using techniques of IV, absorption in the UV-vis region and fluorescence, thermogravimetry (TG), and scanning electron microscopy (SEM). It was observed that the monomer EDOT insertion to copolymer formation contribute for the charges stabilization, being the P(EDOT-co-3FT) the most electrochemical stable material and with lowest charge loss under electrochemical cycling.All the samples had their spectroelectrochemical studied and it was observed that the copolymers showed great potential application in OPVs. The color variation between the reduced and oxidized state was also observed, being that the PEDOT had changed from blue to dark blue, the P3FT from gray to red, and the PFFT from gray and red too. As for the copolymer P(EDOT-co-3FT) changed from blue to purple and the P(EDOTco-FFT) from dark blue to dark purple. The chrono absorptiometry allowed determinate important parameters for application in electrochromic devices, like electrochromic efficiency (), optical contrast (%T) and response time ()

A Nano-modified superhydrophobic membrane

This paper focuses on the synthesis of super-hydrophobic membranes. The polymer used in this research is polystyrene (PS), which has low surface energy but not low enough to be characterized as a superhydrophobic material. As hydrophobicity is based on low energy surface and surface roughness, the electrospinning technique was selected as the manufacturing technique. N, N' dimethylformamide (DMF) was employed as the PS solvent. Two groups of PS/DMF solutions were investigated i.e. 20/80 and 35/65. To increase even more the hydrophobicity, nanoparticles of silica, graphene, cadmium, and zinc were dispersed into the PS/DMF solutions. In contrast to results previous published in literature, the PS/DMF weight ratio of 20/80 led to water contact angles (WCA) of 148º, which is higher than the contact angle for the 35/65 ratio, i.e. 143º. This fact seems to be due to the presence of non-evaporated solvent into the PS surface as the 35/65 solution was more viscous. The WCA for membranes with 0.5 wt. (%) of graphene reached 152º, 149º-153º for membranes with nanosilica addition, 151º with 5.0 wt. (%) CdS, and 153º, 163º and 168º with the addition of 5 wt. (%), 10 wt. (%) and 15 wt. (%) of ZnS, respectively

NEOTROPICAL CARNIVORES: a data set on carnivore distribution in the Neotropics

Mammalian carnivores are considered a key group in maintaining ecological health and can indicate potential ecological integrity in landscapes where they occur. Carnivores also hold high conservation value and their habitat requirements can guide management and conservation plans. The order Carnivora has 84 species from 8 families in the Neotropical region: Canidae; Felidae; Mephitidae; Mustelidae; Otariidae; Phocidae; Procyonidae; and Ursidae. Herein, we include published and unpublished data on native terrestrial Neotropical carnivores (Canidae; Felidae; Mephitidae; Mustelidae; Procyonidae; and Ursidae). NEOTROPICAL CARNIVORES is a publicly available data set that includes 99,605 data entries from 35,511 unique georeferenced coordinates. Detection/non-detection and quantitative data were obtained from 1818 to 2018 by researchers, governmental agencies, non-governmental organizations, and private consultants. Data were collected using several methods including camera trapping, museum collections, roadkill, line transect, and opportunistic records. Literature (peer-reviewed and grey literature) from Portuguese, Spanish and English were incorporated in this compilation. Most of the data set consists of detection data entries (n = 79,343; 79.7%) but also includes non-detection data (n = 20,262; 20.3%). Of those, 43.3% also include count data (n = 43,151). The information available in NEOTROPICAL CARNIVORES will contribute to macroecological, ecological, and conservation questions in multiple spatio-temporal perspectives. As carnivores play key roles in trophic interactions, a better understanding of their distribution and habitat requirements are essential to establish conservation management plans and safeguard the future ecological health of Neotropical ecosystems. Our data paper, combined with other large-scale data sets, has great potential to clarify species distribution and related ecological processes within the Neotropics. There are no copyright restrictions and no restriction for using data from this data paper, as long as the data paper is cited as the source of the information used. We also request that users inform us of how they intend to use the data