Browsing by Subject "Polymers"

Now showing 1 - 6 of 6
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    Direct laser interference patterning of diffraction gratings in Safrofilcon-A hydrogel: fabrication and hydration assessment
    (MDPI, 2021-02-24) Daniel Sola; Sola Martínez, Daniel; Milles, Stephan; Lasagni, Andrés F.; Física
    Refractive index modification by laser micro-structuration of diffractive optical devices in ophthalmic polymers has recently been applied for refractive correction in the fields of optics and ophthalmology. In this work, Safrofilcon-A hydrogel, used as soft contact lenses, was processed by direct laser interference patterning (DLIP) to fabricate linear periodic patterns on the surface of the samples. Periodic modulation of the surface was attained under two-beam interference by using a Q-switched laser source with emission at 263 nm and 4 ns pulse duration. Features of processed areas were studied as a function of both the interference spatial period and the laser fluence. Optical confocal microscopy used to evaluate the topography of the processed samples showed that both structured height and surface roughness increased with laser fluence. Static water contact angle (WCA) measurements were carried out with deionized water droplets on the structured areas to evaluate the hydration properties of DLIP structures. It was observed that the laser structured areas induced a delay in the hydration process. Finally, microstructural changes induced in the structured areas were assessed by confocal micro-Raman spectroscopy showing that at low laser fluences the polymer structure remained almost unaltered. In addition, Raman spectra of hydrated samples recovered the original shape of areas structured at low laser fluence.
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    Fabrication and characterization of diffraction gratings in ophthalmic polymers by using UV direct laser interference patterning
    (Elsevier B.V., 2019-05) Sola, Daniel; Alamri, Sabri; Lasagni, Andrés F.; Artal, Pablo; Física
    The fabrication of diffractive elements in ophthalmic polymers to induce refractive index changes which may be applied for refractive correction is of great interest in the fields of Optics and Ophthalmology. In this work, polyhydroxyethyl-methacrylate and silicone hydrogel polymers used as soft contact lenses were structured with linear periodic patterns by means of Direct Laser Interference Patterning (DLIP). As the laser source, a Q-Switched laser system emitting 10 ns pulses at a wavelength of 266 nm was used to generate the periodic modulation on the surface of the polymer materials. The experiments were carried out employing a two-beam interference setup, studying the features of the laser processed areas as a function of both the laser fluence and the interference period. The topography of the structured areas was investigated using optical confocal microscopy. Compositional and structural modifications on the materials were studied by means of micro-Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Finally, periodic patterns were characterized through diffractive techniques under illumination of a continuous-wave 632.8 nm He-Ne laser to determine the diffractive properties of the DLIP periodic patterns and the refractive index change induced by the laser processing.
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    Latent and polymeric antithrombin: Clearance and potential thrombotic risk
    (Frontiers Media, 2007) Guerrero López, José Antonio; Corral de la Calle, Javier; Rivera Pozo, José; Miñano, Antonia; Alberca, Ignacio; Hernández Espinosa, David; Ordóñez, Adriana; Martínez, Constantino; Navarro-Núñez, Leyre; González-Conejero Hilla, Rocío; Lozano Almela, María Luisa; Vicente García, Vicente; Medicina Interna
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    Scratch-Resistant Hydrophobic Coating with Supramolecular-Polymer Co-Assembly
    (Wiley-VCH, 2023-10-06) Lee, Pin-Wei; Saura Sanmartín, Adrián; Schalley, Christoph A.; Química Orgánica
    Supramolecular assembly for superhydrophobic coatings is known for its efficiency and efficacy. However, the mechanical fragility of the coatings limits their use as coating materials. Herein, the combination of (±)-N,N'-(trans-cyclohexane-1,2-diyl)-bis(perfluorooctanamide) CF7, a cyclohexyl diamide-based low molecular weight gelator, with acrylate polymers for the generation of semi-transparent omniphobic coatings with significantly enhanced scratch proofness is presented. CF7 has shown the ability to self-assemble in common solvents into highly entangled fibrous networks with extreme water repellency. The incorporation of covalent polymers, specifically poly(methyl methacrylate) (PMMA) and poly(trifluoroethyl methacrylate) (PTFEMA), helps to fixate the supramolecular CF7 fibers without interfering with the self-assembled structures. The resulting coatings, namely CF7/PMMA and CF7/PTFEMA, show significantly improved mechanical resistance as well as optical transparency while maintaining excellent water and oil repellency. Furthermore, the homogeneity of the coating in bulk is confirmed by depth profiling of the 3D distribution of the components using time-of-flight secondary ion mass spectrometry imaging, which turns out to be an essential technique in order to characterize such materials.
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    Short-term behavior of different polymer structure lightweight meshes used to repair abdominal wall defects
    (F. Hernández y Juan F. Madrid. Universidad de Murcia. Departamento de Biología Celular e Histología, 2013) Pascual, G.; Hernández-Gascón, B.; Sotomayor, S.; Peña, E.; Calvo, B.; Buján, J.; Bellón, J.M.
    Background. While lightweight (LW) polypropylene (PP) meshes are been used for hernia repair, new prosthetic meshes also of low-density and with large pores have recently been introduced composed of other polymer materials. This study compares the behavior in the short-term of two macroporous LW prosthetic materials, PP and non-expanded PTFE. Methods. Partial defects were created in the lateral wall of the abdomen in New Zealand White rabbits and then repaired using a LW PP mesh or a new monofile, LW PTFE mesh. At 14 days postimplant, shrinkage and tissue incorporation, gene and protein expression of neocollagens (qRT-PCR/immunofluorescence), macrophage response (immunohistochemistry) and biomechanical strength were determined. Results. Both meshes induced good host tissue ingrowth, yet the macrophage response was significantly greater for the PTFE implants (p<0.05). Collagen 1/3 mRNA expression was greater for the PP mesh but differences lacked significance. Similar patterns of collagen I and III protein expression were observed in the neoformed tissue infiltrating the two meshes. After 14 days of implant, tensile strengths were also similar, while elastic modulus values were higher for the PTFE mesh (p<0.05). Conclusions. In the short term, host collagen deposition and biomechanical performance seemed unaffected by the polymer structure of the implanted mesh. In contrast, the inflammatory response to mesh implant produced at this early time point was more intense for the PTFE.
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    The role of thermal accumulation on the fabrication of diffraction gratings in ophthalmic PHEMA by ultrashort laser direct writing
    (MDPI, 2020-12-11) Sola Martínez, Daniel; Vázquez de Aldana, Javier R.; Artal Soriano, Pablo; Física
    The fabrication of diffraction gratings by ultrashort direct laser writing in poly-hydroxyethyl-methacrylate (PHEMA) polymers used as soft contact lenses is reported. Diffraction gratings were inscribed by focusing laser radiation 100 µm underneath the surface of the samples. Low- and high-repetition rate Ti:sapphire lasers with 120 fs pulsewidth working at 1 kHz and 80 MHz respectively were used to assess the role of thermal accumulation on microstructural and optical characteristics. Periodic patterns were produced for different values of repetition rate, pulse energy, laser wavelength, distance between tracks, and scanning speed. Compositional and structural modifications of the processed areas were studied by micro-Raman spectroscopy showing that under certain parameters, thermal accumulation may result in local densification. Far-field diffraction patterns were recorded for the produced gratings to assess the refractive index change induced in the processed areas.