Inorganic-Organic Hybrid Hierarchically Structured Methyl-modified Silica Monoliths

2004 ◽  
Vol 847 ◽  
Author(s):  
Doris Brandhuber ◽  
Nicola Hüsing ◽  
Herwig Peterlik
Keyword(s):  
Liquid Crystalline ◽  
Sol Gel ◽  
Analytical Techniques ◽  
Structural Features ◽  
Water Soluble ◽  
X Ray ◽  
Silica Monoliths ◽  
Organic Hybrid ◽  
X Ray Scattering ◽  
Highly Porous

ABSTRACTHighly porous inorganic-organic hybrid monoliths with mesopores in a macroporous network have been prepared from methyltris(2-hydroxyethoxy)silane (MeGMS) and tetrakis(2-hydroxyethoxy)silane (EGMS) in the presence of an amphiphilic block copolymer. The amount of methyltris(2-hydroxyethoxy)silane (MeGMS) in the gel has been varied from 0 to 100 %. These glycol-modified silanes have the advantage of being water-soluble and thus allowing for a direct templating of liquid-crystalline surfactant mesophases without the presence of a homogenizing organic solvent such as ethanol. The wet gels have been dried by supercritical extraction with carbon dioxide.In the present work, the sol-gel behaviour of these glycol-modified silanes is discussed especially with a focus on the formation of the meso- and macrostructure. In addition, the influences of the varying ratios of methyltris(2-hydroxyethoxy)silane on the structural features of the gels are investigated by various analytical techniques such as small angle X-ray scattering, nitrogen sorption, and scanning electron microscopy.

Structural features of sol-gel-derived hybrid inorganic-organic network ceramer materials by small-angle x-ray scattering

1992 ◽  
Vol 4 (6) ◽  
pp. 1437-1446 ◽  
Author(s):  
D. E. Rodrigues ◽  
A. B. Brennan ◽  
C. Betrabet ◽  
B. Wang ◽  
G. L. Wilkes
Keyword(s):  
Small Angle ◽  
Sol Gel ◽  
Structural Features ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Thermotropic behavior of sodium cholesteryl carbonate

2009 ◽  
Vol 24 (1) ◽  
pp. 156-163 ◽  
Author(s):  
Rabkwan Chuealee ◽  
Timothy S. Wiedmann ◽  
Teerapol Srichana
Keyword(s):  
Phase Behavior ◽  
Chemical Structure ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Wave Number ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
C Nmr

Sodium cholesteryl carbonate ester (SCC) was synthesized, and its phase behavior was studied. The chemical structure was assessed by solid-state infrared spectroscopy based on vibration analysis. The wave number at 1705 and 1276 cm−1 corresponds to a carbonyl carbonate and O–C–O stretching of SCC, respectively. Molecular structure of SCC was further investigated with 1H and 13C NMR spectroscopy. The chemical shift, for the carbonyl carbonate resonance appeared at 155.5 ppm. A molecular mass of SCC was at m/z of 452. Differential scanning calorimetry (DSC), video-enhanced microscopy (VEM) together with polarized light microscopy, and small-angle x-ray scattering (SAXS) were used to characterize the phase behavior as a function of temperature of SCC. Liquid crystalline phase was formed with SCC. Based on the thermal properties and x-ray diffraction, it appears that SCC forms a structure analogous to the type II monolayer structure observed with cholesterol esters.

Inosose-Flüssigkristalle / Inosose Liquid Crystals

1990 ◽  
Vol 45 (7) ◽  
pp. 1084-1090 ◽  
Author(s):  
Klaus Praefcke ◽  
Bernd Kohne ◽  
Andreas Eckert ◽  
Joachim Hempel
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
High Temperature ◽  
Liquid Crystalline ◽  
Structural Features ◽  
Lyotropic Liquid Crystal ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Alkyl Chains

Six S,S-dialkyl acetals 2a-f of inosose (1), tripodal in structure, have been synthesized, characterized and investigated by optical microscopy and differential scanning calorimetry (d.s.c.). The four S,S-acetals 2c-f with sufficiently long alkyl chains are thermotropic liquid crystalline; 2 e and 2 f are even dithermomesomorphic. Each of these four inosose derivatives 2c-f exhibits monotropically a most likely cubic mesophase (MI); in addition 2e and 2f show enantiotropically a hexagonal mesophase (Hx) with a non-covalent, supramolecular H-bridge architecture. Whereas the nature of the optically isotropic mesophase MI needs further clarification the stable high temperature mesophase Hx of 2 e and 2 f has been established by a miscibility test using a sugar S,S-dialkyl acetal also tripodal in structure and with a Hx phase proved by X-ray diffraction, but in contrast to 2 with an acyclic hydrophilic part. Similarities of structural features between the Hx-phases of 2e and 2f as well as of other thermotropic and lyotropic liquid crystal systems are discussed briefly.

Potentialities of an Innovative Technique Like 129Xe NMR and of Saxs for the Characterization of Microporous Sol-Gel Derived SiO2

1996 ◽  
Vol 431 ◽  
Author(s):  
L. C. de Menorval ◽  
A. Julbe ◽  
H. Jobic ◽  
J. A. Dalmon ◽  
C. Guizard
Keyword(s):  
Chemical Shifts ◽  
High Surface ◽  
Sol Gel ◽  
Narrow Pore Size Distribution ◽  
X Ray ◽  
Porous Texture ◽  
129Xe Nmr ◽  
Line Shapes ◽  
X Ray Scattering

AbstractAddition of surfactants in TEOS derived sols leads to micro- or mesoporous materials whose porous texture can be varied by changing the surfactant quantity and/or chain length. This series of materials, with a relatively narrow pore size distribution, is well adapted to study the potentialities of an innovative characterization technique like 129Xe Nuclear Magnetic Resonance in comparison with Small Angle X-ray Scattering and N2 adsorption. SAXS revealed a high surface rugosity of the materials and a good correlation with pore hydraulic radius distributions measured by N2 adsorption. Using 129Xe NMR, we have studied the Xe chemical shifts (δXe,) as a function of pXe, and have pointed out several original results showing the importance, for microporous materials, of the NMR line shapes and of the slope of the lines δXe.=f(pXe).

Time-Resolved Small Angle X-Ray Scattering and Dynamic Light Scattering Studies of Sol-Gel Transition in Gelatin

1988 ◽  
Vol 143 ◽  
Author(s):  
Dan Q. Wu ◽  
Benjamin Chu
Keyword(s):  
Light Scattering ◽  
Cross Section ◽  
Sol Gel ◽  
Slow Mode ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Saxs Intensity ◽  
Sol Gel Transition ◽  
Gel Transition

AbstractStructural and dynamical properties of an aqueous gelatin solution (5 wt%, 0.1M NaCi, pH=7) in a sol-gel transition were studied by time-resolved small angle x-ray scattering (SAXS) and dynamic light scattering (DLS) after quenching the gelatin sol at ∼45”C to 11°C. SAXS intensity measurements suggested the presence of gel fibrils which grew initially in cross-section. The average cross-section of the gel fibrils reached a constant value after an initial growth period of ∼800 sec. Further increase in SAXS intensity could be attributed to the increase in the length of the gel fibrils. Photon correlation, on the other hand, clearly showed two relaxation modes in both the sol and the gel (∼1 hr after the quenching process) states: a fast cooperative diffusion mode which remained constant from the sol to the gel state after correction for the temperature dependence of solvent viscosity; and a slow mode that could be attributed to the self-diffusion of the “free” gelatin chains and aggregates. The slow mode contribution to the time correlation function was reduced from ∼40% in sol to ∼20% in gel signaling a decrease but not the elimination of “free” particles in the gel network. The decrease in the intensity contribution by the slow mode is, however, accompanied by a large increase in the characteristic line-width distribution.

scholarly journals Encapsulation Through The Use Of Emulsified Microemulsions

2021 ◽  
Author(s):  
Ruby R. Rafanan
Keyword(s):  
Controlled Release ◽  
Continuous Phase ◽  
Pharmaceutical Products ◽  
Water Soluble ◽  
Scanning Calorimetry ◽  
Food Grade ◽  
X Ray ◽  
X Ray Scattering ◽  
Food Applications ◽  
Glycerol Monooleate

Emulsified microemulsions (EMEs), first described in detail in 2005 by the group of Garti, consist of a thermodynamically stable water-in-oil microemulsion phase (w1/o) further dispersed within an aqueous continuous phase (w2). These internally-structured w1/o/w2 dispersions are promising controlled release vehicles for water-soluble flavouring compounds, drugs and nutraceuticals. With a stable internal droplet structure, storage stability is improved over non-thermodynamically stable structured emulsions and may exhibit unique controlled release behaviour. Use of food-grade components allows for wider and safer applications in food and pharmaceutical products. In this thesis, a food-grade w1/o microemulsion consisting of glycerol monooleate, tricaprylin and water was dispersed in an aqueous (w2) phase by membrane emulsification and stabilized by a caseinate-pectin complex to produce w1/o/w2 EMEs. The resulting EME showed no signs of phase separation for weeks at room temperature. The microemulsion and EME were characterized by differential scanning calorimetry (DSC), cryo-TEM and small angle x-ray scattering (SAXS) to determine whether the microemulsion’s internal structure was maintained after emulsification. It was shown that EME droplets displayed ordering around the periphery consistent with some loss of microemulsion structure, but maintained the characteristic disordered microemulsion structure at the droplet core. Overall, this research demonstrated the feasibility of developing EME for possible applications in food and non-food applications.

scholarly journals Encapsulation Through The Use Of Emulsified Microemulsions

2021 ◽  
Author(s):  
Ruby R. Rafanan
Keyword(s):  
Controlled Release ◽  
Continuous Phase ◽  
Pharmaceutical Products ◽  
Water Soluble ◽  
Scanning Calorimetry ◽  
Food Grade ◽  
X Ray ◽  
X Ray Scattering ◽  
Food Applications ◽  
Glycerol Monooleate

Emulsified microemulsions (EMEs), first described in detail in 2005 by the group of Garti, consist of a thermodynamically stable water-in-oil microemulsion phase (w1/o) further dispersed within an aqueous continuous phase (w2). These internally-structured w1/o/w2 dispersions are promising controlled release vehicles for water-soluble flavouring compounds, drugs and nutraceuticals. With a stable internal droplet structure, storage stability is improved over non-thermodynamically stable structured emulsions and may exhibit unique controlled release behaviour. Use of food-grade components allows for wider and safer applications in food and pharmaceutical products. In this thesis, a food-grade w1/o microemulsion consisting of glycerol monooleate, tricaprylin and water was dispersed in an aqueous (w2) phase by membrane emulsification and stabilized by a caseinate-pectin complex to produce w1/o/w2 EMEs. The resulting EME showed no signs of phase separation for weeks at room temperature. The microemulsion and EME were characterized by differential scanning calorimetry (DSC), cryo-TEM and small angle x-ray scattering (SAXS) to determine whether the microemulsion’s internal structure was maintained after emulsification. It was shown that EME droplets displayed ordering around the periphery consistent with some loss of microemulsion structure, but maintained the characteristic disordered microemulsion structure at the droplet core. Overall, this research demonstrated the feasibility of developing EME for possible applications in food and non-food applications.

Distribution of water-soluble phthalocyanine in latex polymer according to small-angle X-ray scattering

2013 ◽  
Vol 49 (3) ◽  
pp. 280-285 ◽  
Author(s):  
T. R. Aslamazova ◽  
V. A. Kotenev ◽  
A. A. Shiryaev ◽  
A. Yu. Tsivadze
Keyword(s):  
Small Angle ◽  
Water Soluble ◽  
X Ray ◽  
X Ray Scattering ◽  
Latex Polymer ◽  
Ray Scattering

scholarly journals Structural characterization of the N-terminal part of the MERS-CoV nucleocapsid by X-ray diffraction and small-angle X-ray scattering

2016 ◽  
Vol 72 (2) ◽  
pp. 192-202 ◽  
Author(s):  
Nicolas Papageorgiou ◽  
Julie Lichière ◽  
Amal Baklouti ◽  
François Ferron ◽  
Marion Sévajol ◽  
...  
Keyword(s):  
Structural Model ◽  
Structural Features ◽  
Terminal Region ◽  
X Ray Diffraction ◽  
Terminal Part ◽  
Multifunctional Protein ◽  
X Ray ◽  
N Protein ◽  
Intrinsically Disordered ◽  
X Ray Scattering

The N protein of coronaviruses is a multifunctional protein that is organized into several domains. The N-terminal part is composed of an intrinsically disordered region (IDR) followed by a structured domain called the N-terminal domain (NTD). In this study, the structure determination of the N-terminal region of the MERS-CoV N proteinviaX-ray diffraction measurements is reported at a resolution of 2.4 Å. Since the first 30 amino acids were not resolved by X-ray diffraction, the structural study was completed by a SAXS experiment to propose a structural model including the IDR. This model presents the N-terminal region of the MERS-CoV as a monomer that displays structural features in common with other coronavirus NTDs.

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