Browsing by Keyword "Organic Chemistry"
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Item Additive Manufactured Scaffolds for Bone Tissue Engineering: Physical Characterization of Thermoplastic Composites with Functional Fillers: Physical Characterization of Thermoplastic Composites with Functional Fillers(2021-08-13) Sinha, Ravi; Sanchez, Alberto; Camara-Torres, Maria; Uriszar-Aldaca, Iñigo Calderon; Calore, Andrea Roberto; Harings, Jules; Gambardella, Ambra; Ciccarelli, Lucia; Vanzanella, Veronica; Sisani, Michele; Scatto, Marco; Wendelbo, Rune; Perez, Sergio; Villanueva, Sara; Matanza, Amaia; Patelli, Alessandro; Grizzuti, Nino; Mota, Carlos; Moroni, Lorenzo; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓN; Tecnalia Research & InnovationThermoplastic polymer–filler composites are excellent materials for bone tissue engineering (TE) scaffolds, combining the functionality of fillers with suitable load-bearing ability, biodegradability, and additive manufacturing (AM) compatibility of the polymer. Two key determinants of their utility are their rheological behavior in the molten state, determining AM processability and their mechanical load-bearing properties. We report here the characterization of both these physical properties for four bone TE relevant composite formulations with poly(ethylene oxide terephthalate)/poly(butylene terephthalate (PEOT/PBT) as a base polymer, which is often used to fabricate TE scaffolds. The fillers used were reduced graphene oxide (rGO), hydroxyapatite (HA), gentamicin intercalated in zirconium phosphate (ZrP-GTM) and ciprofloxacin intercalated in MgAl layered double hydroxide (MgAl-CFX). The rheological assessment showed that generally the viscous behavior dominated the elastic behavior (G″ > G′) for the studied composites, at empirically determined extrusion temperatures. Coupled rheological–thermal characterization of ZrP-GTM and HA composites showed that the fillers increased the solidification temperatures of the polymer melts during cooling. Both these findings have implications for the required extrusion temperatures and bonding between layers. Mechanical tests showed that the fillers generally not only made the polymer stiffer but more brittle in proportion to the filler fractions. Furthermore, the elastic moduli of scaffolds did not directly correlate with the corresponding bulk material properties, implying composite-specific AM processing effects on the mechanical properties. Finally, we show computational models to predict multimaterial scaffold elastic moduli using measured single material scaffold and bulk moduli. The reported characterizations are essential for assessing the AM processability and ultimately the suitability of the manufactured scaffolds for the envisioned bone regeneration application.Item Development of self-contained microcapsules for optimised catalyst position in self-healing materials(2020-01-20) Rodriguez, Raquel; Bekas, Dimitrios G.; Flórez, Sonia; Kosarli, Maria; Paipetis, Alkiviadis S.; POLIMEROSSelf-contained microcapsules for use in self-healing epoxy resin are successfully synthesized by suspension polymerization process. The microencapsulation of an epoxy resin using Polymethylmethacrylate (PMMA) as a shell material and the location of scandium triflate (Sc(OTf)3) as the catalyst into microcapsules shell during the microencapsulation processes is presented (PMMA/Sc(OTf)3-walled microcapsules). Spherical microcapsules of 80 μm in diameter with a liquid core content of 30 wt% (determined by HPLC) are produced. Catalyst location on microcapsules are assessed qualitatively by SEM-EADS and quantitatively by TGA showing high yields (⁓70 wt%). The evaluation of the healing efficiency was assessed in terms of fracture toughness recovery. PMMA/Sc(OTf)3-walled microcapsules showed an increased healing efficiency than that of conventional PMMA-walled capsule. The healing efficiency of the PMMA-walled capsules was 46.7 and 55.1% when the system healed at 80 and 120 °C, respectively. However, in the case of PMMA/Sc(OTf)3-walled microcapsules healing efficiency increased to 57.5 and 79.1% for the same healing temperatures.Item Effect of the biobased polyols chemical structure on high performance thermoset polyurethane properties(2022-12-16) Echeverria-Altuna, O.; Ollo, O.; Larraza, I.; Gabilondo, N.; Harismendy, I.; Eceiza, A.; POLIMEROS; Tecnalia Research & InnovationThe sustainability of the polymeric materials has become a fundamental challenge; therefore, the development of new biobased formulations has gained increasing interest. Thermoset polyurethanes (PURs) present high performance and are a competitive solution for structural composites. However, polyols used in the PUR synthesis are typically from petrochemical origin. Nowdays, a broad range of biobased polyols is available in the market, but there is not yet a specific formulation for high performance PURs composites. The aim of this work was to study the effect of biobased polyols' characteristics in the PUR processing and final properties. In addition, biobased polyol features to synthesize BIO-PURs suitable for structural applications were stablished. The viscosity and reactivity were studied by means of rheology and differential scanning calorimetry (DSC). Thermal and mechanical properties were studied through thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and flexural tests. The results obtained demonstrated the dramatic influence of polyols’ nature on BIO-PUR/PUR properties and their effect on the crosslink density. It was observed that using a high functionality and high hydroxyl index biobased polyol, it was possible to synthesize high performance BIO-PUR suitable for structural composites.Item Effect of the catalyst system on the reactivity of a polyurethane resin system for RTM manufacturing of structural composites(2022-03) Echeverria-Altuna, Oihane; Ollo, Olatz; Calvo-Correas, Tamara; Harismendy, Isabel; Eceiza, Arantxa; Tecnalia Research & Innovation; POLIMEROSThe high versatility of polyurethanes (PU’s) is encouraging the development of new formulations for new appli cations, like their use as a matrix for structural composites. PU’s based technology offers some advantages, such as fatigue resistance and fast curing cycles. However, their high reactivity hinders some manufacturing processes like Resin Transfer Moulding (RTM). This work aimed to achieve a PU resin (PUR) formulation with the required latency and reactivity for the RTM. For this purpose, different catalytic systems based on an epoxide and LiCl were investigated. The reactivity of the systems was evaluated through Differential Scanning Calorimetry (DSC) and rheology tests, and the curing reaction and viscosity were modelled. Furthermore, the RTM process of a representative composite part was simulated. Results demon strated the processability improvements when the LiCl was incorporated into the isocyanate component of the formulation combined with a monool or a diol. It was observed that these combinations contribute to the encapsulation of the LiCl between the as formed urethane groups by hydrogen bonding, providing the desired latency and acting as a delayed action catalyst. Once the reaction started and the encapsulation was deactivated, an alkoxide was formed to act as a catalyst. En capsulation was more effective with the diol, providing a higher latency.Item Effects of Human and Porcine Adipose Extracellular Matrices Decellularized by Enzymatic or Chemical Methods on Macrophage Polarization and Immunocompetence(2021-04-08) Cicuéndez, Mónica; Casarrubios, Laura; Feito, María José; Madarieta, Iratxe; Garcia-Urkia, Nerea; Murua, Olatz; Olalde, Beatriz; Briz, Nerea; Diez-Orejas, Rosalía; Portolés, María Teresa; Biomateriales; SGThe decellularized extracellular matrix (ECM) obtained from human and porcine adipose tissue (AT) is currently used to prepare regenerative medicine bio-scaffolds. However, the influence of these natural biomaterials on host immune response is not yet deeply understood. Since macrophages play a key role in the inflammation/healing processes due to their high functional plasticity between M1 and M2 phenotypes, the evaluation of their response to decellularized ECM is mandatory. It is also necessary to analyze the immunocompetence of macrophages after contact with decellularized ECM materials to assess their functional role in a possible infection scenario. In this work, we studied the effect of four decellularized adipose matrices (DAMs) obtained from human and porcine AT by enzymatic or chemical methods on macrophage phenotypes and fungal phagocytosis. First, a thorough biochemical characterization of these biomaterials by quantification of remnant DNA, lipids, and proteins was performed, thus indicating the efficiency and reliability of both methods. The proteomic analysis evidenced that some proteins are differentially preserved depending on both the AT origin and the decellularization method employed. After exposure to the four DAMs, specific markers of M1 proinflammatory and M2 anti-inflammatory macrophages were analyzed. Porcine DAMs favor the M2 phenotype, independently of the decellularization method employed. Finally, a sensitive fungal phagocytosis assay allowed us to relate the macrophage phagocytosis capability with specific proteins differentially preserved in certain DAMs. The results obtained in this study highlight the close relationship between the ECM biochemical composition and the macrophage’s functional role.Item Enhancing Osteoconduction of PLLA-Based Nanocomposite Scaffolds for Bone Regeneration Using Different Biomimetic Signals to MSCs(2012-02) Ciapetti, Gabriela; Granchi, Donatella; Devescovi, Valentina; Baglio, Serena R.; Leonardi, Elisa; Martini, Desirèe; Jurado, Maria Jesus; Olalde, Beatriz; Armentano, Ilaria; Kenny, Josè M.; Walboomers, Frank X.; Alava, J.I.; Baldini, Nicola; Tecnalia Research & Innovation; BiomaterialesIn bone engineering, the adhesion, proliferation and differentiation of mesenchymal stromal cells rely on signaling from chemico-physical structure of the substrate, therefore prompting the design of mimetic “extracellular matrix”-like scaffolds. In this study, three-dimensional porous poly-L-lactic acid (PLLA)-based scaffolds have been mixed with different components, including single walled carbon nanotubes (CNT), micro-hydroxyapatite particles (HA), and BMP2, and treated with plasma (PT), to obtain four different nanocomposites: PLLA + CNT, PLLA + CNTHA, PLLA + CNT + HA + BMP2 and PLLA + CNT + HA + PT. Adult bone marrow mesenchymal stromal cells (MSCs) were derived from the femur of orthopaedic patients, seeded on the scaffolds and cultured under osteogenic induction up to differentiation and mineralization. The release of specific metabolites and temporal gene expression profiles of marrow-derived osteoprogenitors were analyzed at definite time points, relevant to in vitro culture as well asin vivo differentiation. As a result, the role of the different biomimetic components added to the PLLA matrix was deciphered, with BMP2-added scaffolds showing the highest biomimetic activity on cells differentiating to mature osteoblasts. The modification of a polymeric scaffold with reinforcing components which also work as biomimetic cues for cells can effectively direct osteoprogenitor cells differentiation, so as to shorten the time required for mineralization.Item Fluidized Bed Membrane Reactors for Ultra Pure H2 Production - A Step forward towards Commercialization(2016-03-19) Helmi, Arash; Fernandez, Ekain; Melendez, Jon; Pacheco Tanaka, David A.; Gallucci, Fausto; van Sint Annaland, Martin; TECNOLOGÍAS DE HIDRÓGENO; Tecnalia Research & Innovation; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSIn this research the performance of a fluidized bed membrane reactor for high temperature water gas shift and its long term stability was investigated to provide a proof-of-concept of the new system at lab scale. A demonstration unit with a capacity of 1 Nm3/h of ultra-pure H2 was designed, built and operated over 900 h of continuous work. Firstly, the performance of the membranes were investigated at different inlet gas compositions and at different temperatures and H2 partial pressure differences. The membranes showed very high H2 fluxes (3.89E 6 mol m 2 Pa 1 s 1 at 400 C and 1 atm pressure difference) with a H2/N2 ideal perm-selectivity (up to 21,000 when integrating five membranes in the module) beyond the DOE 2015 targets. Monitoring the performance of the membranes and the reactor confirmed a very stable performance of the unit for continuous high temperature water gas shift under bubbling fluidization conditions. Several experiments were carried out at different temperatures, pressures and various inlet compositions to determine the optimum operating window for the reactor. The obtained results showed high hydrogen recovery factors, and very low CO concentrations at the permeate side (in average <10 ppm), so that the produced hydrogen can be directly fed to a low temperature PEM fuel cell.Item Morphology and N2 Permeance of Sputtered Pd-Ag Ultra-Thin Film Membranes(2016-02-10) Fernandez, Ekain; Sanchez-Garcia, Jose Angel; Viviente, J.L.; van Sint Annaland, Martin; Gallucci, Fausto; Pacheco Tanaka, David A.; Tecnalia Research & Innovation; TECNOLOGÍAS DE HIDRÓGENO; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThe influence of the temperature during the growth of Pd-Ag films by PVD magnetron sputtering onto polished silicon wafers was studied in order to avoid the effect of the support roughness on the layer growth. The surfaces of the Pd-Ag membrane films were analyzed by atomic force microscopy (AFM), and the results indicate an increase of the grain size from 120 to 250–270 nm and film surface roughness from 4–5 to 10–12 nm when increasing the temperature from around 360–510 K. After selecting the conditions for obtaining the smallest grain size onto silicon wafer, thin Pd-Ag (0.5–2-µm thick) films were deposited onto different types of porous supports to study the influence of the porous support, layer thickness and target power on the selective layer microstructure and membrane properties. The Pd-Ag layers deposited onto ZrO2 3-nm top layer supports (smallest pore size among all tested) present high N2 permeance in the order of 10−6 mol•m−2•s−1•Pa−1 at room temperature.Item Polyurethane/acrylic hybrid dispersions containing phosphorus reactive flame retardants as transparent coatings for wood(2022-09) Puyadena, M.; Etxeberria, I.; Martin, L.; Mugica, A.; Agirre, A.; Cobos, M.; Gonzalez, A.; Barrio, A.; Irusta, L.; BIOECONOMÍA Y CO2Phosphorus modified polyurethane/acrylic hybrid dispersions were prepared for flame retardant transparent wood coatings. The polymerisation was carried out in three steps. In the first one, the polyurethane was synthesised using an acrylic monomer as solvent. The second step involved water addition that promoted the phase inversion and lastly, acrylic part was polymerised. The phosphorous compounds were covalently linked to polyurethane using a phosphorylated polyol and to the acrylic phase using an acrylic phosphate. Polymerisation was monitored by FTIR and NMR and the molar mass of the hybrids was measured by AF4 and SEC. The effects of the phosphorus in fire-retardant properties were analysed by thermogravimetry and pyrolysis combustion flow calorimetry. The introduction of phosphorus did not produce significant changes in the polymerisation process but promoted the cross-linking of the coatings. The coated wood samples maintained the transparency and good properties with the introduction of phosphorus and presented a slight reduction in the Peak Heat Release Rate measured by cone calorimeter. The action of phosphorus as a fire retardant was effective as it gave rise to significant reduction of the CO and CO2 peaks.Item Recent Advances in Pd-Based Membranes for Membrane Reactors(2017-01-01) Arratibel Plazaola, Alba; Pacheco Tanaka, David A.; Van Sint Annaland, Martin; Gallucci, Fausto; Tecnalia Research & Innovation; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSPalladium-based membranes for hydrogen separation have been studied by several research groups during the last 40 years. Much effort has been dedicated to improving the hydrogen flux of these membranes employing different alloys, supports, deposition/production techniques, etc. High flux and cheap membranes, yet stable at different operating conditions are required for their exploitation at industrial scale. The integration of membranes in multifunctional reactors (membrane reactors) poses additional demands on the membranes as interactions at different levels between the catalyst and the membrane surface can occur. Particularly, when employing the membranes in fluidized bed reactors, the selective layer should be resistant to or protected against erosion. In this review we will also describe a novel kind of membranes, the pore-filled type membranes prepared by Pacheco Tanaka and coworkers that represent a possible solution to integrate thin selective membranes into membrane reactors while protecting the selective layer. This work is focused on recent advances on metallic supports, materials used as an intermetallic diffusion layer when metallic supports are used and the most recent advances on Pd-based composite membranes. Particular attention is paid to improvements on sulfur resistance of Pd based membranes, resistance to hydrogen embrittlement and stability at high temperature.Item Supercritical hydrothermal flow synthesis of xonotlite nanofibers(2018-06-01) Díez-García, Marta; Gaitero, J.J.; Santos, J.I.; Dolado, Jorge S.; Aymonier, Cyril; Tecnalia Research & Innovation; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNThis article reports a satisfactory and innovative method for the synthesis of xonotlite using a flow reactor and supercritical water. This study widens the variety of inorganic nanofibers produced in record breaking times by means of continuous reactors working under supercritical water conditions. In particular, the synthesis time of xonotlite, which takes normally more than 5 h, was reduced to only 20s by carrying out the reaction at 400 °C and 23.5 MPa. Resulting product was studied by several characterization techniques: x-ray diffraction, transmission electron microscopy, 29Si and 1H nuclear magnetic resonance and infrared spectroscopy. Furthermore, obtained product consisted of highly pure and crystalline flat nanofibers of 1–10 μm long with a length to diameter ratio of the order of 100. Also, the typical deviation from the ideal structure observed by nuclear magnetic resonance and the presence of Si-OH were explained in terms of surface defects. This work reinforces the interests of using supercritical conditions for the fast synthesis of crystalline nano-calcium silicates which, due to the number of potential industrial applications and the scalability of the technology, might represent technological breakthrough.