Nucleation and growth mechanisms of poly(furan): effect of electrolyte and monomer concentration in acetonitrile

Valle, M.; Ugalde, L.; Pino, Flavio del; Díaz, F. R.; Bérnède, J.C.

doi:10.1590/s0103-50532004000200018

Cited by 17 publications

(10 citation statements)

References 17 publications

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“…Consequently, it is essential to know and characterize the involved processes and to identify and quantify the parameters that control them. In this context the determination of the nucleation and growth mechanism, NGM, of these polymers has been very useful [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Nucleation and growth mechanisms during electropolymerization of substituted 3-alkylthiophenes

Soto

Díaz

Valle

et al. 2008

Applied Surface Science

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Section: Introductionmentioning

confidence: 99%

“…Further on its use has been extended to electropolymerization, even though both processes are not quite the same [6]. Metal electro-deposition takes place by reduction of the respective cation from a solution containing a suitable supporting electrolyte.…”

Section: Introductionmentioning

confidence: 99%

Nucleation and growth mechanisms during electropolymerization of substituted 3-alkylthiophenes

Soto

Díaz

Valle

et al. 2008

Applied Surface Science

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“…20 s), which can be explained by considering that the electrode employed possesses a relatively large area (it takes time to plate the total surface). The kinetics of the reaction also influences this process since, compared with other polymers deposition, [14][15][16][17] coalescence of the nuclei takes much more time here.…”

Section: Resultsmentioning

confidence: 99%

“…Then, when supersaturation is reached, clusters are deposited onto the electrode, which induces nuclei growth. [14][15][16][17][18] Different processes can be involved in the NGM and, often, they can occur simultaneously (or successively). The dominant process depends on the experimental conditions and on the variation of the electropolymerization time.…”

Section: Introductionmentioning

confidence: 99%

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Nucleation and growth mechanism of polycarbazole deposited by electrochemistry

Abe¹,

Ugalde²,

Valle³

et al. 2007

J. Braz. Chem. Soc.

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Neste trabalho foram estudados os mecanismos de nucleação e de crescimento (MNC) de camadas finas de policarbazol (PCz) depositadas por eletro-oxidação de carbazol em LiClO 4 + acetonitrila anidra sobre um substrato de vidro coberto com SnO 2 , usando método potenciostático. Os transientes corrente-tempo (j-t) obtidos foram ajustados usando uma equação matemática que levou em conta três contribuições: a nucleação instantânea com crescimento bidimensional (IN2D) e tridimensional (IN3D) e, também, a nucleação progressiva com crescimento tridimensional (PN3D). No começo, a contribuição IN2D predomina mas, rapidamente, o processo IN3D passa a ser o mais importante. Para tempos de deposição t ≥ 17 s, IN3D corresponde a 80% da corrente total. A visualização da morfologia da superfície das películas de PCz via microscopia eletrônica de varredura (SEM) concorda com o MNC proposto pelo método matemático. A película cobre muito rapidamente a camada de SnO 2 que está relacionada ao processo bidimensional, 2D, mesmo que se observe alguma heterogeneidade distribuída aleatoriamente na película, proveniente do processo tridimensional, 3D. Após dois minutos de deposição, a rugosidade de toda a superfície dos depósitos corrobora a predominância dos processos 3D. Conseqüentemente, a informação obtida diretamente a partir dos transientes (j-t) é uma ferramenta muito conveniente e útil para predizer as condições de trabalho com o intuito de controlar o tipo de morfologia da película preparada por eletro-polimerização.Polycarbazole (PCz) thin films have been deposited by electro-oxidation of carbazole in LiClO 4 + anhydrous acetonitrile onto SnO 2 coated glass substrates, by potentiostatic method and the nucleation and growth mechanism (NGM) were studied. The obtained current time transients (j-t) were fitted using a mathematical equation with three contributions: instantaneous nucleation with two-dimensional (IN2D) or three-dimensional (IN3D) growth, and also a progressive nucleation with three dimensional (PN3D) growth. At the beginning, the IN2D contribution is predominant but, quickly the IN3D processes become more important. At a deposition time t ≥ 17 s the IN3D corresponds to 80 % of the total current. The visualization by scanning electron microscopy of the surface morphology of the PCz films is in agreement with the NGM proposed by the mathematical method. The film covers very rapidly the SnO 2 under layer related to the 2D process, even if some heterogeneities randomly distributed in the films, issued from the 3D processes, are also visible. After two minutes of deposition, the roughness of the whole surface of the films corroborates the 3D processes domination. Therefore, the information directly obtained from the (j-t) transients is a suitable and very useful tool to predict the working conditions in order to control the type of morphology of the film prepared by electropolymerization.

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Synthesis of 3′,4′‐disubstituted terthiophenes. Characterization and electropolymerization. I. 3′,4′‐dibromo‐2,2′:5′,2″‐terthiophene in photovoltaic display

Vélez

Díaz

Valle

et al. 2006

J of Applied Polymer Sci

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BACKGROUND: Ewing sarcoma (ES) was a malignant tumor of bone or soft tissue. One of the few risk factors for developing ES is race, with a higher incidence noted in populations of European rather than African or Asian ancestry. The goal of the current study was to evaluate racial and ethnic differences in presentation and overall survival (OS) among patients diagnosed with ES before age 40 years. METHODS: Data from the Surveillance, Epidemiology, and End Results database identified 1715 patients aged <40 years who were diagnosed with ES between 1973 and 2005. Racial and ethnic group differences were compared using chi‐square tests. OS was estimated by Kaplan‐Meier analysis and compared using log‐rank tests and Cox models. RESULTS: Black patients had significantly more soft‐tissue tumors compared with white non‐Hispanic patients (P <.0001). Asian and white Hispanic patients were found to have an intermediate frequency of soft‐tissue tumors that also differed from white non‐Hispanic patients (P <.0001). White Hispanic patients presented with a higher proportion of larger tumors compared with white non‐Hispanic patients (P = .042). Black patients tended to be older than white non‐Hispanic patients (P = .012). Sex, frequency of pelvic tumors, and metastatic status did not appear to differ by ethnicity or race. OS was found to differ according to race and ethnicity. Even after controlling for known confounders, OS was significantly worse for black, Asian, and white Hispanic patients compared with white non‐Hispanic patients (P = .0031, P = .0182, and P = .0051, respectively). CONCLUSIONS: Ethnic and racial differences in characteristics and outcomes of patients with ES do exist. Understanding the etiology of these differences will require further study. Cancer 2010. © 2010 American Cancer Society.

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Nucleation and growth mechanisms of poly(furan): effect of electrolyte and monomer concentration in acetonitrile

Cited by 17 publications

References 17 publications

Nucleation and growth mechanisms during electropolymerization of substituted 3-alkylthiophenes

Nucleation and growth mechanisms during electropolymerization of substituted 3-alkylthiophenes

Nucleation and growth mechanism of polycarbazole deposited by electrochemistry

Synthesis of 3′,4′‐disubstituted terthiophenes. Characterization and electropolymerization. I. 3′,4′‐dibromo‐2,2′:5′,2″‐terthiophene in photovoltaic display

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