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29 results on '"Nogales, Aurora"'

3. Structure Development in Polymers during Fused Filament Fabrication (FFF): An in Situ Small- and Wide-Angle X-ray Scattering Study Using Synchrotron Radiation

Author

Nogales, Aurora, primary, Gutiérrez-Fernández, Edgar, additional, García-Gutiérrez, Mari-Cruz, additional, Ezquerra, Tiberio A., additional, Rebollar, Esther, additional, Šics, Igors, additional, Malfois, Marc, additional, Gaidukovs, Sergejs, additional, Ge̅cis, Egils, additional, Celms, Kristofers, additional, and Bakradze, Georgijs, additional

Published
2019
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22. Film-Forming Polymers Containing in the Main-Chain Dibenzo Crown Ethers with Aliphatic (C10−C16), Aliphatic−Aromatic, or Oxyindole Spacers

Author

Zolotukhin, Mikhail G., primary, Hernández, María del Carmen G., additional, Lopez, Ana Maria, additional, Fomina, Loudmila, additional, Cedillo, Gerardo, additional, Nogales, Aurora, additional, Ezquerra, Tiberio, additional, Rueda, Daniel, additional, Colquhoun, Howard M., additional, Fromm, Katharina M., additional, Ruiz-Treviño, Alberto, additional, and Ree, Moonhor, additional

Published
2006
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26. Directional Crystallization of 20 nm Width PolymerNanorods by the Inducement of Heterogeneous Nuclei at Their Tips.

Author

Martín, Jaime, Nogales, Aurora, and Mijangos, Carmen

Subjects
*NANORODS, *NANOSTRUCTURED materials, *DIFFUSION processes, *CRYSTALLINE polymers, *CRYSTAL growth, *NUCLEATION
Abstract

Crystallization of polymers underconfinement has emerged as anew tool to fall into some of the classical problems of the crystallizationof polymers. Furthermore, these investigations are essential to obtainnanostructures with a customized behavior, as the most important propertiesof such nanostructure (mechanical, optical, electrical, etc.) stronglydepend on the crystalline features. Here we show a new crystallizationstrategy for achieving a completely oriented crystallization of ultrasmallpolymer rods (20 nm in diameter) by inducing crystal nucleation centersexclusively at one of their tips. Such heterogeneous nucleation takesplace at a temperature tens of degrees higher than the temperatureat which the crystal nuclei would be spontaneously formed (via a homogeneousmechanism), so the formation of additional nuclei along the nanorodscan be ruled out. Therefore, the confined polymer crystallizes unidirectionallyalong the nanorod axis just by the growth of already formed crystals.This strategy opens up the possibility of preparing polymer nanorodspresenting considerably improved crystalline features. Thus, our nanorodsshow single-crystal orientation and high crystallinity. Interestingly,the new strategy also allows studying for the first time the kineticsof the unidirectional crystal growth under confinement. Thus, we showthat the crystallization of the polymer nanorods shows the time dependencyof a diffusion process, i.e., t0.5. Moreover,the linear crystallization rate value of the confined flat on lamellaeis of 2.7 × 10–7cm/s. Since the polymer nanorodscrystallize exclusively through of the growth of crystals heterogeneouslynucleated at one of their tips, and just a single flat on lamellacan be accommodated in a 20 nm in diameter pores due to space reasons,what we present in this paper may be the study of the crystallizationof a single lamella within each pore, which would mean that single-crystallinenanorods are obtained from the melt. [ABSTRACT FROM AUTHOR]

Published
2013
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28. The Smectic–IsotropicTransition of P3HT Determinesthe Formation of Nanowires or Nanotubes into Porous Templates.

Author

Martín, Jaime, Nogales, Aurora, and Martín-González, Marisol

Subjects
*NANOWIRES, *NANOTUBES, *POROUS materials, *MICROFABRICATION, *THIOPHENES, *CHEMICAL templates, *NANOPORES, *DIFFUSION
Abstract

We present the simple and controllable fabrication ofordered arraysof poly(3-hexylthiophene) (P3HT) solid nanowires and hollow nanotubesby infiltrating the molten polymer into AAO nanopores at temperaturespromoting partial (260 °C) and complete (280 °C) wettingregimes, respectively. We show that such wetting regimes (and thusthe formation of nanowires or nanotubes) are associated with a differentinternal structure in the P3HT melt. At 260 °C, the P3HT organizesinto a smectic mesophase. Thus, the translational motion of the P3HTmolecule through the phase-separated structure would involve an enthalpicpenalty, which prevents the molecular diffusion required for achievingthe complete wetting regime. Consequently, the P3HT wets the nanoporesin partial wetting regime, so that solid nanowires are formed. Incontrast, the melt is structurally isotropic at 280 °C, whichpromotes the complete wetting regime, yielding nanotubes. Such a smecticmesophase is also present in P3HT confined into 350 nm in diameterpores. Furthermore, we observe the formation of a new type of nanostructureconsisting of twinned nanotubes (two pores formed from one originalpore) as a consequence of the appearance of a longitudinal meniscuswhich divided the hollow interior of the initial nanotube into twoindependent compartments. Lastly, we use the capillary rise of theP3HT melt along the cylindrical nanopores as a “coarse”nanoscale viscosimetry experiment for the measurement of its viscosityvalue under confinement. The physical behavior observed for P3HT mightbe extrapolated to other semiconducting polymers with similar comblikemolecular architectures with applications in optoelectronics, thermoelectrics,and photovoltaics (like other poly(alkylthiophenes), polycarbazoles,polyfluorenes, polyphenylenes, etc.). [ABSTRACT FROM AUTHOR]

Published
2013
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29. Film-Forming Polymers Containing in the Main-Chain Dibenzo Crown Ethers with Aliphatic (C10−C16), Aliphatic−Aromatic, or Oxyindole Spacers

Author

G. Zolotukhin, Mikhail, del Carmen G. Hernández, María, Maria Lopez, Ana, Fomina, Loudmila, Cedillo, Gerardo, Nogales, Aurora, Ezquerra, Tiberio, Rueda, Daniel, M. Colquhoun, Howard, M. Fromm, Katharina, Ruiz-Treviño, Alberto, and Ree, Moonhor

Abstract

Novel, linear, soluble, high-molecular-weight, film-forming polymers and copolymers in which main-chain crown ether units alternate with aliphatic (C10−C16) units have been obtained for the first time from aromatic electrophilic substitution reactions of crown ethers by aliphatic dicarboxylic acids followed by reduction of the carbonyl groups. The crown ether unit is dibenzo-18-crown-6, dibenzo-21-crown-7, dibenzo-24-crown-8, or dibenzo-30-crown-10; the aliphatic spacer is derived from a dicarboxylic acid (sebacic, 1,12-dodecanedicarboxylic, hexadecanedioic or 1,4-phenylenediacetic acids). The reactions were performed at 35 °C in a mixture of methanesulfonic acid (MSA) with phosphorus pentoxide, 12:1 (w/w), (Eaton's reagent). The carbonyl groups in the polyketones obtained were completely reduced to methylene linkages by treatment at room temperature with triethylsilane in a mixture of trifluoroacetic acid and dichloromethane. Polymers containing in the main chain crown ethers alternating with oxyindole fragments were prepared by one-pot condensation of crown ethers with isatin in a medium of Eaton's reagent. A possible reaction mechanism is suggested. According to IR and NMR analyses, the polyacylation reactions lead to the formation of isomeric (syn/anti-substituted) crown ether units in the main chain. The polymers obtained were soluble in the common organic solvents, and flexible transparent films could be cast from the solutions. DSC and X-ray studies of the polymers with “symmetrical” crown ethers reveal the presence of the endotherms corresponding to the supramolecular assemblies.

Published
2006
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