Nano-scale Creep Compliance of Hybrid Aerogels

2011 ◽  
Vol 1306 ◽  
Author(s):  
N. de la Rosa-Fox ◽  
V. Morales-Flórez ◽  
M. Piñero ◽  
L. Esquivias
Keyword(s):  
Elastic Deformation ◽  
Creep Compliance ◽  
Sol Gel ◽  
Liquid Mixtures ◽  
Potential Growth ◽  
Organic Precursor ◽  
Power Ultrasound ◽  
Inorganic Particles ◽  
High Power Ultrasound ◽  
Hybrid Aerogels

ABSTRACTThe copolymerization between TEOS (tetraethoxysilane) and silane derivatives was promoted by the application of high power ultrasound to the precursor liquid mixtures in the same way as in the classical sol-gel method. The specific organic precursor was selected from the silanol-terminated polymer family with different molecular functionality and the inorganic precursor was from the silicon alkoxide family. Ultrasound, through the acoustic cavitation process, influences the formation of a very fine distribution of silica particles and avoids cyclidation of the polymer, thus favoring copolymerization with the inorganic particles and leading to the formation of a highly porous and rubber-like solid aerogel. Creep compliance curves, corresponding to the time-dependent depth response to a step load, are imprint site dependent, with pore, soft and stiff sites discerned. In all cases, an instantaneous elastic deformation is apparent. For longer test times, depending on the imprint sites, elastic deformation and newtonian flow produce the rise and fall of the creep curve. Linear parts of the curve on a log-log scale indicate potential growth with small exponents for the creep compliance level. Isochrones stress-strain diagrams show a superlinear trend and an increase with time, which reveals the nonlinear viscoelasticity of these hybrid aerogels. The elasto-plastic response to creep can be tuned by the molecular functionality of the different silane derivatives studied.

Bioactive organic-inorganic hybrid aerogels

2004 ◽  
Vol 847 ◽  
Author(s):  
Luis Esquivias ◽  
Víctor Morales-Flórez ◽  
Manuel Piñero ◽  
Nicolás de la Rosa-Fox ◽  
Julio Ramírez ◽  
...  
Keyword(s):  
Colloidal Silica ◽  
Pore Radius ◽  
Silica Particles ◽  
Inorganic Hybrid ◽  
Power Ultrasound ◽  
High Power Ultrasound ◽  
Porous Volume ◽  
Preliminary Study ◽  
Hybrid Aerogels

ABSTRACTWe have prepared organic-inorganic hybrid materials (OIHM), incorporating an organic phase in the inorganic precursor sol, using high power ultrasound for assistance with agitation. A sono-ormosil results after gelation. Colloidal silica particles have been added to these hybrids to enable network porous volume and pore radius to be tailored to specific requirements. Finally, in vitro bioactivity of this material has been promoted by adding calcium to the initial sol. The structure and bioactivity of these materials have been subjected to preliminary study, including their mechanical behaviour. These materials have a very fine structure especially after colloidal silica particles have been included. When immersed in a solution simulating blood plasma, they are bioactive, and the sample with colloid particles presents a better behaviour in vitro

scholarly journals Synthesis and Characterization of Nano-Sized 4-Aminosalicylic Acid–Sulfamethazine Cocrystals

Pharmaceutics ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 277 ◽  
Author(s):  
Ala’ Salem ◽  
Anna Takácsi-Nagy ◽  
Sándor Nagy ◽  
Alexandra Hagymási ◽  
Fruzsina Gősi ◽  
...  
Keyword(s):  
High Power ◽  
Active Pharmaceutical Ingredient ◽  
Polymorphic Form ◽  
Degree Of Crystallinity ◽  
Dissolution Enhancement ◽  
Aminosalicylic Acid ◽  
Nano Technology ◽  
Power Ultrasound ◽  
High Power Ultrasound ◽  
High Degree

Drug–drug cocrystals are formulated to produce combined medication, not just to modulate active pharmaceutical ingredient (API) properties. Nano-crystals adjust the pharmacokinetic properties and enhance the dissolution of APIs. Nano-cocrystals seem to enhance API properties by combining the benefits of both technologies. Despite the promising opportunities of nano-sized cocrystals, the research at the interface of nano-technology and cocrystals has, however, been described to be in its infancy. In this study, high-pressure homogenization (HPH) and high-power ultrasound were used to prepare nano-sized cocrystals of 4-aminosalysilic acid and sulfamethazine in order to establish differences between the two methods in terms of cocrystal size, morphology, polymorphic form, and dissolution rate enhancement. It was found that both methods resulted in the formation of form I cocrystals with a high degree of crystallinity. HPH yielded nano-sized cocrystals, while those prepared by high-power ultrasound were in the micro-size range. Furthermore, HPH produced smaller-size cocrystals with a narrow size distribution when a higher pressure was used. Cocrystals appeared to be needle-like when prepared by HPH compared to those prepared by high-power ultrasound, which had a different morphology. The highest dissolution enhancement was observed in cocrystals prepared by HPH; however, both micro- and nano-sized cocrystals enhanced the dissolution of sulfamethazine.

FeAl2O4 Nanopowders; Structural Analysis and Band Gap Energy

2017 ◽  
Vol 36 (8) ◽  
pp. 789-793 ◽  
Author(s):  
Morteza Enhessari
Keyword(s):  
Structural Analysis ◽  
Band Gap ◽  
Sol Gel ◽  
Band Gap Energy ◽  
Mixed Metal Oxide ◽  
Nanoscale Materials ◽  
X Ray Diffraction ◽  
Organic Precursor ◽  
Gap Energy ◽  
Acid Gel

AbstractNanoscale FeAl2O4 was successfully synthesized via sol–gel method. The sol constituents containing iron and aluminum cations were formed homogenously in stearic acid gel (formation of organic precursor). The pure structural analysis and the size of the spinels were confirmed by X-ray diffraction (XRD). It was observed that the size of the nanoscale materials obtained at around 30–40nm. The micrographs of FeAl2O4 evidenced the homogenous and nanosize formation of spinel. The semiconducting behavior of this mixed metal oxide was observed at 3.14eV based on the band gap energy (Eg). The final nanoscale materials exhibited a superparamagnetic behavior with a saturation magnetization of 9.8 emu/g at applied field of 10 kOe.

scholarly journals Silica synthesis by the sol-gel method and its use in the preparation of multifunctional biocomposites

2014 ◽  
Vol 12 (2) ◽  
pp. 173-184 ◽  
Author(s):  
Łukasz Klapiszewski ◽  
Michał Królak ◽  
Teofil Jesionowski
Keyword(s):  
Electrode Materials ◽  
Sol Gel ◽  
Statistical Design ◽  
Morphological Properties ◽  
Statistical Design Of Experiments ◽  
Organic Precursor ◽  
Gel Method ◽  
Sol Gel Method ◽  
Non Invasive ◽  
Silica Synthesis

AbstractThis study focuses on the optimization process of silica synthesis using the sol-gel method while applying a statistical design of experiments which was based on a multilevel mathematical model. The product obtained in the process of optimized synthesis, characterized by the best dispersive and morphological parameters, was used for the preparation of organic/inorganic composites. The organic precursor was Kraft lignin, a high-molecular natural polymer. Synthesis of silica/lignin biocomposites was carried out by three proposed methods. The physicochemical properties and dispersive-morphological properties of each product were determined using the following available methods: Scanning Electron Microscopy — SEM, Non-Invasive Back-Scattering — NIBS, Fourier Transform Infrared Spectroscopy — FT-IR, Thermogravimetric analysis — TG and others. The electrokinetic and thermal properties of the biocomposites sufficed to be applied for example, as a cheap and biodegradable polymer filler. Further areas of application of these composites were sought, especially in electrochemistry as the advanced electrode materials.

scholarly journals Highly Mixed ZrO2/SiO2 Hybrid Aerogel Deriving from Freely Tangled Weakly Branched Primary Clusters Enables Improved Thermal Stability and Excellent Thermal Insulating Performance.

2019 ◽  
Author(s):  
Benxue Liu ◽  
Min Gao
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Sol Gel ◽  
Single Component ◽  
Thermal Stabilities ◽  
Crystallization Behaviors ◽  
Thermal Insulating ◽  
Enhanced Properties ◽  
Hybrid Aerogels ◽  
Hybrid Aerogel

In compared with single component aerogel, hybrid aerogel with multi-components possessing enhanced properties, especially high thermal stabilities which are our concerns in this paper, are the promised materials in various applications. However, how the mixing between variable components within hybrid aerogel affects their properties still not very clear and needs more research efforts. In the present research, we chose a ZrO<sub>2</sub>/SiO<sub>2</sub> hybrid aerogel as represent to study their mixing and the resulted thermal stabilities. We designed a series of ZrO<sub>2</sub>/SiO<sub>2</sub> hybrid aerogels with variable ZrO<sub>2</sub>/SiO<sub>2</sub> ratio deriving from tailored sol-gel parameters, and then studied their shrinkages, nanopore collapses and crystallization behaviors upon heat-treatment.

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