Person: Espinal Viguri, Maialen
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Espinal Viguri
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Maialen
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Ciencias
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0000-0003-0227-9458
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811866
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Publication Open Access Hybrid xerogels: study of the sol-gel process and local structure by vibrational spectroscopy(MDPI, 2021) Cruz Quesada, Guillermo; Espinal Viguri, Maialen; López Ramón, María Victoria; Garrido Segovia, Julián José; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate PublikoaThe properties of hybrid silica xerogels obtained by the sol-gel method are highly dependent on the precursor and the synthesis conditions. This study examines the influence of organic substituents of the precursor on the sol-gel process and determines the structure of the final materials in xerogels containing tetraethyl orthosilicate (TEOS) and alkyltriethoxysilane or chloroalkyltri-ethoxysilane at different molar percentages (RTEOS and ClRTEOS, R = methyl [M], ethyl [E], or propyl [P]). The intermolecular forces exerted by the organic moiety and the chlorine atom of the precursors were elucidated by comparing the sol-gel process between alkyl and chloroalkyl series. The microstructure of the resulting xerogels was explored in a structural theoretical study using Fourier transformed infrared spectroscopy and deconvolution methods, revealing the distribution of (SiO)4 and (SiO)6 rings in the silicon matrix of the hybrid xerogels. The results demonstrate that the alkyl chain and the chlorine atom of the precursor in these materials determines their inductive and steric effects on the sol-gel process and, therefore, their gelation times. Furthermore, the distribution of (SiO)4 and (SiO)6 rings was found to be consistent with the data from the X-ray diffraction spectra, which confirm that the local periodicity associated with four-fold rings increases with higher percentage of precursor. Both the sol-gel process and the ordered domains formed determine the final structure of these hybrid materials and, therefore, their properties and potential applications.Publication Open Access Tunability of hybrid silica xerogels: surface chemistry and porous texture based on the aromatic precursor(MDPI, 2023) Rosales Reina, Beatriz; Cruz Quesada, Guillermo; Padilla-Postigo, Nataly; Irigoyen-Razquin, Marian; Alonso-Martínez, Ester; López Ramón, María Victoria; Espinal Viguri, Maialen; Garrido Segovia, Julián José; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate PublikoaThe interest in new materials with specific properties has increased because they are essential for the environmental and technological needs of our society. Among them, silica hybrid xerogels have emerged as promising candidates due to their simple preparation and tunability: when they are synthesised, depending on the organic precursor and its concentration, their properties can be modulated, and thus, it is possible to prepare materials with à la carte porosity and surface chemistry. This research aims to design two new series of silica hybrid xerogels by co-condensation of tetraethoxysilane (TEOS) with triethoxy(p-tolyl)silane (MPhTEOS) or 1,4-bis(triethoxysilyl)benzene (Ph(TEOS)2 and to determine their chemical and textural properties based on a variety of characterisation techniques (FT-IR, 29Si NMR, X-ray diffraction and N2 , CO2 and water vapour adsorption, among others). The information gathered from these techniques reveals that depending on the organic precursor and its molar percentage, materials with different porosity, hydrophilicity and local order are obtained, evidencing the easy modulation of their properties. The ultimate goal of this study is to prepare materials suitable for a variety of applications, such as adsorbents for pollutants, catalysts, films for solar cells or coatings for optic fibre sensors.Publication Open Access Hybrid xerogels doped with Tb(III) and Eu (III) and a water soluble Pybox ligand(2021) Cruz Quesada, Guillermo; Espinal Viguri, Maialen; Garrido Segovia, Julián José; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; CienciasHybrid organic-inorganic siliceous materials (ORMOSiLs) are a key focus within the nanoscience area as they combine advantages of inorganic materials without losing characteristics intrinsic of organic molecules. In the past years, our research group has designed hybrid siliceous xerogels (HSXG) with porosities and surface chemistries on demand for a range of applications, such as coatings for optic fiber sensors [1]. Although hybrid xerogels are mainly amorphous materials, recent studies by our group have demonstrated that introducing specific organic fragments on the precursors can induce selforganization during the sol-gel process to obtain a series of transparent nanostructured HSXG [2]. In the present work, a step forward is taken in the applicability of this type of HSXG by doping them with Tb(III) or Eu (III) cations and a water-soluble pybox-based antenna ligand (Pybox-EG= 2,2′-(4-(2-Ethoxyethoxy)pyridine-2,6-diyl)bis(4,5-dihydrooxazole)). Inclusion of photoluminescence will provide the materials with new properties and therefore new applications in fiber optic sensors (FOS) or in solar cells devices.Publication Open Access New hybrid organochlorinated xerogels(2021) Cruz Quesada, Guillermo; Espinal Viguri, Maialen; López Ramón, María Victoria; Garrido Segovia, Julián José; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; CienciasHybrid silica xerogels (HSXG) combine the properties of organic and inorganic components in the same material, which makes them promising and versatile candidates for multiple applications. These materials can be easily prepared by the sol-gel process, which offers the possibility to obtain different morphologies. The incorporation of organic precursors plays an important role in their properties, hence, allowing the design of materials for specific applications such as coatings for optical fibers [1]. The aim of this work was to study the influence of the alkyl chain and chlorine atom on the morphological and textural properties of various hybrid materials produced by co-condensation. For this purpose, three series of hybrid xerogels were prepared by co-condensation of TEOS and a chloroalkyltriethoxysilane (TEOS:ClRTEOS, R = methyl, ethyl or propyl) at different molar ratios. The influence of the precursors on the structure and textural properties of the xerogels was studied by means of N2 adsorption, XRD (X-ray diffraction), 29Si NMR (nuclear magnetic resonance) and FE-SEM (Field Emission-scanning electron microscope) [2].Publication Open Access Novel silica hybrid xerogels prepared by co-condensation of TEOS and ClPhTEOS: a chemical and morphological study(MDPI, 2022) Cruz Quesada, Guillermo; Espinal Viguri, Maialen; López Ramón, María Victoria; Garrido Segovia, Julián José; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2The search for new materials with improved properties for advanced applications is, nowadays, one of the most relevant and booming fields for scientists due to the environmental and technological needs of our society. Within this demand, hybrid siliceous materials, made out of organic and inorganic species (ORMOSILs), have emerged as an alternative with endless chemical and textural possibilities by incorporating in their structure the properties of inorganic compounds (i.e., mechanical, thermal, and structural stability) in synergy with those of organic compounds (functionality and flexibility), and thus, bestowing the material with unique properties, which allow access to multiple applications. In this work, synthesis using the sol-gel method of a series of new hybrid materials prepared by the co-condensation of tetraethoxysilane (TEOS) and 4-chlorophenyltriethoxysilane (ClPhTEOS) in different molar ratios is described. The aim of the study is not only the preparation of new materials but also their characterization by means of different techniques (FT-IR, 29Si NMR, X-ray Diffraction, and N2/CO2 adsorption, among others) to obtain information on their chemical behavior and porous structure. Understanding how the chemical and textural properties of these materials are modulated with respect to the molar percentage of organic precursor will help to envisage their possible applications: From the most conventional such as catalysis, adsorption, or separation, to the most advanced in nanotechnology such as microelectronics, photoluminescence, non-linear optics, or sensorics.