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At least 19 recordsLinked to original sources
PubMed2001

Adsorption study of alkyl-silicas and methylsiloxy-silicas.

We report the synthesis and adsorption study of the lyophobic porous silicas. Four adsorbents were prepared and tested: (1) octyl-silica, (2) hexadecyl-silica, (3) bis(trimethylsiloxy)-silica, and (4) oligo(dimethylsiloxane)-silica. Octyl- and hexadecyl-silicas were prepared via the reaction of silica with (CH3)2NSi(CH3)2CnH(2n+1) (n=8 and 16), the reactions were carried under the optimized conditions yielding high bonding densities of alkyl groups approximately 2.9-3.0 groups/nm2 and highly uniform non-polar adsorbents. Bis(trimethylsiloxy)-silica was prepared via the reaction silica with ClSi(CH3)2(CH2)10Si(CH3)[OSi(CH3)3]2. Oligo(dimethylsiloxane)-silica was prepared via the reaction of silica with ClSi(CH3)2-[OSi(CH3)2]2-Cl. Adsorption of small organic compounds (n-alkanes, alkylbenzene, benzene, diethyl ether) was investigated using two methods, classical static adsorption and gas chromatography. Thermodynamic parameters (heat, Gibbs energy, and entropy) of the adsorption of organic compounds were studied as a function of the nature of adsorbate and of the nature of the bonded layer as well. The results obtained suggest penetration of the adsorbate molecules into the bonded layer and the importance of this process in the retention mechanism in gas chromatography. Energy of the dispersion interactions with the surface decreases in the following order: n-C16H33(CH3)2Si- > n-C8H17(CH3)2Si- > [(CH3)3SiO]2Si(CH3)-(CH2)10(CH3)2Si- > -[[(CH3)2SiO]2]x-(CH3)2Si-. Energy of the electrostatic and hydrogen bonding interactions with the surface, as assessed from the adsorption of benzene and diethyl ether molecules, decreases in the opposite direction, indicating that alkyl-silicas are less polar adsorbents than methylsiloxy-silicas.

Adsorption↗
PubMed2001

Characteristics of Alkyltrimethoxysilane-Treated Fumed Silicas and Rheological Behavior of Fumed Silica Suspensions in an Epoxy Resin.

Fumed silica was surface treated by hexyl (C6), octyl (C8), decyl (C10), hexadecyl (C16), and octadecyl(C18)trimethoxysilanes, and the products were evaluated from various aspects. The amounts of alkyl group introduced on silica surface were all within the range from 22 to 25 mmol/100 g. Such fumed silicas were suspended in an epoxy resin, bisphenol type A, and their rheological properties were measured. The rheological behavior of the silica suspensions was investigated as to steady-state viscosity and dynamic moduli in order to examine the effect of alkyl chain length on interactions of hydrophobic groups on the silica surface. The stronger shear thinning behavior was observed in the surface-modified fumed silica with longer alkyl groups. However, the suspensions of the nontreated fumed silica and the fumed silicas treated by C6 silane showed Newtonian behavior even at the silica concentration of 7 wt%. The dynamic moduli G' of the silica suspensions increased with increasing alkyl chain length. The interaction of hydrophobic groups on the silica surface is mainly attributed to the rheological behavior of fumed silica suspensions in the epoxy resin. Copyright 2001 Academic Press.

Journal Article↗
PubMed2002

Dental resin composites containing silica-fused whiskers--effects of whisker-to-silica ratio on fracture toughness and indentation properties.

Dental resin composites need to be strengthened in order to improve their performance in large stress-bearing applications such as crowns and multiple-unit restorations. Recently, silica-fused ceramic whiskers were used to reinforce dental composites, and the whisker-to-silica ratio was found to be a key microstructural parameter that determined the composite strength. The aim of this study was to further investigate the effects of whisker-to-silica ratio on the fracture toughness, elastic modulus, hardness and brittleness of the composite. Silica particles and silicon carbide whiskers were mixed at whisker:silica mass ratios of 0:1, 1:5. 1:2, 1:1, 2:1, 5:1, and 1:0. Each mixture was thermally fused, silanized and combined with a dental resin at a filler mass percentage of 60%. Fracture toughness was measured with a single-edge notched beam method. Elastic modulus and hardness were measured with a nano-indentation system. Whisker:silica ratio had significant effects on composite properties. The composite toughness (mean+/-SD; n = 9) at whisker:silica = 2:1 was (2.47+/-0.28) MPa m(1/2), significantly higher than (1.02+/-0.23) at whisker:silica = 0:1, (1.13+/-0.19) of a prosthetic composite control, and (0.95+/-0.11) of an inlay/onlay composite control (Tukey's at family confidence coefficient = 0.95). Elastic modulus increased monotonically and hardness plateaued with increasing the whisker:silica ratio. Increasing the whisker:silica ratio also decreased the composite brittleness, which became about 1/3 of that of the inlay:onlay control. Electron microscopy revealed relatively flat fracture surfaces for the controls, but much rougher ones for the whisker composites, with fracture steps and whisker pullout contributing to toughness. The whiskers appeared to be well-bonded with the matrix, probably due to the fused silica producing rough whisker surfaces. Reinforcement with silica-fused whiskers resulted in novel dental composites that possessed fracture toughness two times higher than, and brittleness less than half of current dental composites.

Carbon Compounds, Inorganic↗
PubMed2003

Fluorescence imaging of the desorption of dye from fused silica versus silica gel.

The desorption rate constants for a cationic dye from strong adsorption sites are compared for the same chromatographic interface but for two different substrates, fused silica and chromatographic silica gel. The dye is 1,1'-didodecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (DiI). The interface consists of acetonitrile and a hydrocarbon monolayer (C8) covalently bound to the silica substrate. To measure slow desorption from fused silica, fluorescence imaging combined with correlation spectroscopy is used. To measure slow desorption from silica gel, fluorescence movies of silica gel particles are used. In both cases, the results show that there are two types of slow desorption processes on time scales exceeding 1 s. The desorption time from one type of site is within an experimental error of 7 s for both silica substrates. The adsorption kinetics for this type of site are slow, and the equilibrium population of DiI on these sites is comparable to that for DiI weakly adsorbed to the hydrocarbon monolayer. For the second type of site, for fused silica, the population of DiI is even higher than that of weakly adsorbed DiI, and the desorption time constant is approximately 2 min, although this is likely shortened by photobleaching. For silica gel, the relative population of DiI on this ultrastrong site is more than an order of magnitude lower, and the desorption time constant is 4.0 +/- 0.1 min. Both silica substrates thus show two types of sites whose time constants agree within experimental error, suggesting that the strong adsorption sites on fused silica are chemically the same as those on chromatographic silica gel.

Journal Article↗
PubMed2000

Solid dosage form preparations from oily medicines and their drug release. Effect Of degree of surface-modification of silica gel on the drug release from phytonadione-loaded silica gels.

A surface-modified silica gel was produced to improve the surface affinity to an oily medicine, phytonadione (VK1). The effect of the degree of surface modification of the silica gel on the drug release behavior from the silica porous matrix was investigated. The silica gels were surface-modified using the silan coupling agent, 3-methacryloxypropyltrimethoxysilane (C7), octadecyltriethoxysilane (C18), or 3,3,3-trifluoropropyltrimethoxysilane (F3). A mixture of VK1 solution and surface-modified silica gel was evaporated under reduced pressure at room temperature, then the resulting powder was dried in vacuo. The degree of surface modification was evaluated based upon elementary analysis. The dissolution profiles of the samples were investigated in Japanese Pharmacopoeia XII, 1st fluid buffer (pH 1.2, 37+/-0.5 degrees C) containing 1.5% sodium lauryl sulfate. The FT-IR spectra of VK1-loaded surface-modified silica gels suggested that the amount of hydrogen-bonded VK1 with the silanol group on the gel surface decreased with increasing hydrophobicity of the silica gel. Since the modified group was rotating on the silica gel surface, and inhibited the adsorption of VK1 to the surface, the attractive molecular interaction between VK1 and the silica gel surface might decrease with increasing length of the modified functional group. However, the characteristics of the affinity of VK1 to the functional groups significantly differed among the groups. The VK1 release from the modified silica gels was initially rapid, slowed markedly after 1 h, and continued for more than 24 h. The amount of VK1 released from the modified surface silica gels by C7, C18 or F3 increased with increasing density of the surface modification group. The mean drug release moment (MDT) decreased with an increase in surface-modified group density.

Adsorption↗
PubMed1988

Generation of free radicals from freshly fractured silica dust. Potential role in acute silica-induced lung injury.

Data presented here indicate that freshly fractured silica exhibits surface characteristics and biologic reactivity distinct from aged silica, and on this basis we propose that these surface features may lead to enhanced manifestations of lung injury. Grinding of silica produces approximately 10(18) Si and Si-O (silicon-based) radicals per gram of dust on the particulate surface which are characterized by an electron spin resonance (ESR) spectrum centered around g = 2.0015. These silicon-based radicals react with aqueous media to produce OH radicals, which are demonstrable using a DMPO spin trap. The concentration of silicon-based radicals in silica decreases with aging in air and exhibits a half-life of approximately 30 h, whereas its ability to generate OH radicals in aqueous solution decreases with a half-life of approximately 20 h. However, on storage in aqueous media, the concentration of silicon-based radicals and the dust's ability to generate OH radicals decrease significantly within a few minutes. Freshly ground silica is also more biologically reactive than aged silica, because freshly crushed silica activates a greater respiratory burst in alveolar macrophages than aged silica, i.e., storage of ground dust in air decreases silica-induced superoxide anion secretion, hydrogen peroxide release, and NBT reduction by 25%, 68%, and 43%, respectively. Furthermore, compared to aged silica, freshly ground silica exhibits a greater cytotoxic effect on cellular membrane integrity, i.e., a 1.5-fold increase in LDH release from macrophages, a 36-fold increase in hemolytic activity, and a three-fold increase in the ability to induce lipid peroxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed2000

Effects of whisker-to-silica ratio on the reinforcement of dental resin composites with silica-fused whiskers.

Resin composites need to be strengthened to improve their performance in large stress-bearing restorations. This study aimed to reinforce composites with whiskers and to investigate the effects of the whisker:silica ratio. It was hypothesized that changing the whisker-silica ratio would affect the whisker-matrix bonding and the filler's distribution, and hence alter the composite properties. Silica particles and whiskers were mixed at various whisker:silica mass ratios, thermally fused, and combined with a dental resin at filler mass fractions of 0-65%. Whisker:silica ratio and filler level had significant effects on composite properties. At 60% filler level, the silica composite (whisker:silica = 0:1) had a flexural strength (mean +/- SD; n = 6) of 104 +/- 21 MPa; that at a whisker:silica ratio of 1:0 was 74 +/- 36 MPa. However, that of the silica-fused whisker composite (whisker:silica = 5:1) was 210 +/- 14 MPa, compared with 109 +/- 23 MPa and 114 +/- 18 MPa of two prosthetic controls. Mixing silica with whiskers minimized whisker entanglement, improved filler distribution in the matrix, and facilitated whisker silanization and bonding to the matrix, thus resulting in substantially stronger composites.

Carbon Compounds, Inorganic↗
PubMed1991

Response of alveolar macrophages to in vitro exposure to freshly fractured versus aged silica dust: the ability of Prosil 28, an organosilane material, to coat silica and reduce its biological reactivity.

We have reported previously that crushing or grinding crystalline silica results in the generation of silica-based radicals on the particulate surface and that these radicals can generate hydroxyl radicals in aqueous solution. Data in the present study indicate that freshly ground silica is more cytotoxic and is a more potent activator of alveolar macrophages than comparably sized aged silica. That is, compared to aged silica, fresh silica is 4.2-fold more potent in decreasing the membrane integrity of macrophages; is 50% more potent in activating hydrogen peroxide secretion by macrophages; and is 4.6-fold more potent in stimulating cellular chemiluminescence. Prosil 28, an organosilane material, is an effective coating agent for fresh silica. It decreases the cytotoxicity of fresh silica by as much as 78% and decreases the ability of fresh silica to induce chemiluminescence from alveolar macrophages by 58%. The data suggest that surface radicals associated with freshly cleaved dust may be an important factor in the induction of pulmonary disease. Furthermore, treating dust with coating agents may substantially decrease toxicity.

Animals↗
PubMed1995

Activation of murine macrophages by silica particles in vitro is a process independent of silica-induced cell death.

We have tested the murine macrophagic cell line RAW 264.7 for its ability to undergo activation after exposure to silica particles in vitro. When exposed to silica under controlled conditions (each cell having access to about 10 silica particles), RAW 264.7 cells were able to phagocytose the particles. Concomitantly, there was a significant increase in tumor necrosis factor alpha (TNF alpha) mRNA accumulation and TNF alpha secretion. The level of TNF alpha production by RAW 264.7 cells increased up to 5-fold 48 h after phagocytosis of silica particles with very low cell toxicity. The phagocytic stimulus did not induce nitric oxide production. When cells were exposed to a higher number of silica particles, cell activation was attained at shorter times but a substantial number of cells were damaged at 48 h. Interferon gamma (IFN gamma) alone induced an increased production of TNF alpha in RAW 264.7 cells, not further augmented by a subsequent exposure to silica of the IFN gamma-treated cells. Other macrophage-like cell lines as well as primary peritoneal macrophages were able to phagocytose silica particles but showed different abilities to produce and secrete TNF alpha once phagocytosis took place. Therefore, RAW 264.7 cells were chosen as a model for in vitro studies of the long-term response of macrophages to silica.

Animals↗
PubMed2003

Capillary electrochromatography with monolithic silica column: I. Preparation of silica monoliths having surface-bound octadecyl moieties and their chromatographic characterization and applications to the separation of neutral and charged species.

Monolithic silica columns with surface-bound octadecyl (C18) moieties have been prepared by a sol-gel process in 100 microm ID fused-silica capillaries for reversed-phase capillary electrochromatography of neutral and charged species. The reaction conditions for the preparation of the C18-silica monoliths were optimized for maximum surface coverage with octadecyl moieties in order to maximize retention and selectivity toward neutral and charged solutes with a sufficiently strong electroosmotic flow (> 2 mm/s) to yield rapid analysis time. Furthermore, the effect of the pore-tailoring process on the silica monoliths was performed over a wide range of treatment time with 0.010 M ammonium hydroxide solution in order to determine the optimum time and conditions that yield mesopores of narrow pore size distribution that result in high separation efficiency. Under optimum column fabrication conditions and optimum mobile phase composition and flow velocity, the average separation efficiency reached 160 000 plates/m, a value comparable to that obtained on columns packed with 3 microm C18-silica particles with the advantages of high permeability and virtually no bubble formation. The optimized monolithic C18-silica columns were evaluated for their retention properties toward neutral and charged analytes over a wide range of mobile phase compositions. A series of dimensionless retention parameters were evaluated and correlated to solute polarity and electromigration property. A dimensionless mobility modulus was introduced to describe charged solute migration and interaction behavior with the monolithic C18-silica in a counterflow regime during capillary electrochromatography (CEC )separations. The mobility moduli correlated well with the solute hydrophobic character and its charge-to-mass ratio.

Alkanes↗
PubMed2003

Silicon-silica nanowires, nanotubes, and biaxial nanowires: inside, outside, and side-by-side growth of silicon versus silica on zeolite.

It was demonstrated that zeolite can be used as a pseudo-template to grow very fine and uniform silicon nanostructures via disproportionation reaction of SiO by thermal evaporation. Three distinct types of composite nanowires and nanotubes of silicon and silica were grown on the surfaces of zeolite Y pellets. The first type is formed by an ultrafine crystalline silicon nanowire sheathed by an amorphous silica tube (a silicon nanowire inside a silica nanotube). The second type is formed by a crystalline silicon nanotube filled with amorphous silica (a silicon nanotube outside a silica nanowire). The third type is a biaxial silicon-silica nanowire structure with side-by-side growth of crystalline silicon and amorphous silica. These silicon nanostructures exhibit unusually intense photoluminescence (in comparison to ordinary silicon nanowires).

Journal Article↗
PubMed2003

Effect of silica sand on activation energy for diffusion of sodium ions in montmorillonite and silica sand mixture.

The effect of silica sand on the diffusion of sodium ions in mixtures of montmorillonite and silica sand was studied by measuring the apparent diffusion coefficients, activation energies for diffusion, and the basal spacing of the mixed samples. These diffusion experiments suggest that the apparent diffusion coefficients of sodium ions in the mixed samples were almost the same as those of pure montmorillonite samples having the same partial dry densities of montmorillonite. The activation energy dependence for diffusion of sodium ions on the partial dry density was different between the mixed samples and the pure montmorillonite samples. The activation energy increased by adding silica sand at the partial dry density of 1.0 Mg m(-3), and decreased by adding silica sand at the partial dry densities higher than 1.2 Mg m(-3). A change in the XRD profile was observed after adding silica sand at the partial dry density of 1.6 Mg m(-3). Here, a three-water-layer hydrate state of montmorillonite was found in the mixed sample whereas only a two-water-layer hydrate state was observed in the pure montmorillonite sample. These experimental results suggest that silica sand changed the montmorillonite microstructure in the mixed samples, which then altered the sodium-ion diffusion process.

Bentonite↗
PubMed1996

Apatite formation on silica gel in simulated body fluid: its dependence on structures of silica gels prepared in different media.

It has been shown that the prerequisite for glasses and glass-ceramics to bond to living bone is the formation of a layer of biologically active bonelike apatite on their surfaces. The hydrated silica formed on the surfaces of glasses and glass-ceramics plays an important role in nucleating the apatite. In the present study, the structure of the hydrated silica responsible for the apatite nucleation was investigated in an accellular simulated body fluid with ion concentrations nearly equal to those of human blood plasma. Three kinds of porous silica gels were prepared by hydrolysis and polycondensation of tetraethoxysilane in pure water or in aqueous solution containing polyethylene glycol or polyacrylic acid. The silica gels prepared in aqueous solution containing polyethylene glycol or polyacrylic acid had micron-size interconnected pores, whereas the gel prepared in pure water did not. All the gels contained a large volume of nanometer-size pores, almost the same amounts of silanol groups and D2 defect, and showed a high dissolution rate of the silica. Despite this, only the gel prepared in the solution containing polyethylene glycol formed the apatite on its surface in the simulated body fluid. This indicates that only a certain type of structural unit of the silanol group is responsible for the apatite nucleation.

Acrylates↗
PubMed1999

Microwave Dielectric Relaxation of Bound Water to Silica, Alumina, and Silica-Alumina Gel Suspensions.

By the use of a time domain reflectomery method, dielectric measurements were carried out on silica, alumina, and silica-alumina gel suspensions (five types with composition varying between 0.3 < Si/Al atomic ratio <0.8) in the frequency range of 100 kHz to 20 GHz. For all the gels, a relaxation peak due to bound water was observed. This peak locates at around 1-10 MHz, indicating that the peak is a decade or 10 decades lower than those of biological polymers such as an aqueous DNA solution. The silica and alumina gels have a different bound water structure, judging from the fact that the peaks are different in their locations and shapes between the two gels. The silica-alumina gels exhibit two different peaks other than the peak of bulk water. The sum of the relaxation strength on the two peaks is proportional to the monolayer capacity obtained from water vapor isotherms. The shape of the one peak holds that of the silica gel, whereas the other retains that of alumina gel, and furthermore the ratio of the relaxation strength on the former peak to that on the latter depends on Si/Al atomic ratio. It is suggested that both peaks are caused by the orientation of bound water molecules. Copyright 1999 Academic Press.

Journal Article↗
PubMed2003

Possible role of ubiquitin in silica biomineralization in diatoms: identification of a homologue with high silica affinity.

In diatom silicon biomineralization peptides are believed to play a role in silica precipitation and the consequent structure direction of the cell wall. Characterization of such peptides should reveal the nature of this organic-inorganic interaction, knowledge that may eventually well be used to expand the existing range of artificial silicas ("biomimicking"). Biochemical studies on Navicula pelliculosa revealed a set of proteins, which have a high affinity for a solid silica matrix; some were only eluted from the matrix when SDS-denaturation was applied. One of the proteins with an affinity for silica, about 8.5 kDa, is shown to be a homologue of ubiquitin on the basis of its N-terminal amino acid sequence; ubiquitin itself is a highly conserved 8.6 kDa protein that is involved in protein degradation. This finding is in line with a model of silica biomineralization in diatoms that implies the removal of templating polypeptides when pores in the growing cell wall develop. Western blotting with specific anti-ubiquitin antibodies confirmed cross-reactivity. Immunocytochemical localization of ubiquitin indicates that it is present along the diatom cell wall and inside pores during different stages of valve formation.

Biomimetic Materials↗
PubMed1996

Heparin attenuates bleomycin but not silica-induced pulmonary fibrosis in mice: possible relationship with involvement of myofibroblasts in bleomycin, and fibroblasts in silica-induced fibrosis.

Pulmonary fibrosis was elicited in mice or rats by the intratracheal instillation of bleomycin or silica. Daily injections of heparin significantly reduced the collagen deposition in bleomycin, but not in silica, injected mice, as evaluated by the lung hydroxyproline content on day 15 after instillation. Heparin also reduced the bleomycin-induced morbidity and mortality. Study of the broncho-alveolar lavage fluid (BAL) detected no significant change in the number of leucocytes or the amount of protein in heparin treated mice. Histologies of bleomycin instilled mice suggested that heparin did reduce the alveolar remodelling but not the alveolitis, evidenced by leucocytic infiltration. As detected by electron microscopy (EM), bleomycin increased the number of leucocytes and platelets within the alveolar capillaries but this was not significant ly reduced by heparin. The phenotype of the interstitial cell involved in these two types of pulmonary fibrosis was investigated by immunohistochemistry and EM. While in bleomycin injected animals the interstitial cells had the phenotype of an actin (alpha-actin in the rat) and lipid containing interstitial cell, with a poorly developed RE, in silica injected animals in contrast, the interstitial cells were without cytoplasmic actin or lipid but with a markedly developed endoplasmic reticulum (ER). Thus bleomycin and silica induced the growth of two different types of interstitial cells, the myofibroblast and the regular fibroblast, which might be a reason why heparin selectively inhibits bleomycin but not silica-induced fibrosis.

Animals↗
PubMed1995

Direct interaction between crystalline silica and DNA - a proposed model for silica carcinogenesis.

Crystalline silica in aqueous buffer produced oxygen radicals that mediated in vitro DNA (deoxyribonucleic acid) strand breakage. The oxidized DNA base, thymine glycol, was also produced. The hydroxyl radical, responsible for most DNA damage, has a reaction distance of about 15 Angstroms, requiring close contact of silica with DNA. Fourier transform infrared spectroscopy of incubations of quartz particles with DNA showed distinct alterations in both DNA and quartz spectra and therefore indicated extensive hydrogen bonding between surface silanol groups and the phosphate-sugar backbone of DNA. Electron microscopy and energy dispersive X-ray spectroscopy of alveolar epithelial cells in fetal rat lung, exposed to quartz in culture, showed localization of quartz particles in the nuclei and mitotic spindles. Direct interaction of crystalline silica with DNA may be important in silica carcinogenesis by anchoring DNA close to sites of free radical production on the silica surface, or by interfering with DNA replication, repair, or the mitotic process.

Animals↗
PubMed2000

Sol-gel polycondensation in a cyclohexane-based organogel system in helical silica: creation of both right- and left-handed silica structures by helical organogel fibers.

Chiral amide- and urea-type organic gelators (1-6), based on cyclohexanediamine, have been prepared, and the superstructures of the organogels were evaluated by circular dichroism (CD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The CD spectrum of the amide-based organogel system 1+2 exhibited a negative sign for the first Cotton effect, indicating that the dipole moments in the gelator aggregate orient into an anticlockwise direction. In contrast, the system 3+4 has a positive sign for the first Cotton effect, indicating that they orient into a clockwise direction. In the mixture of urea- and amide-based organogels, CD spectra of 5+2 and 6+4 revealed negative and positive signs, respectively. The helical structure of the amide-based organogels 1+2 and 3+4 clearly showed left- and right-handed structures, respectively, by SEM. To transcribe the chiral, helical structures of the organogels into silica gel, the sol-gel polycondensation of tetraethoxysilane (TEOS) was carried out in acetonitrile or ethanol. Very surprisingly, the left- and right-handed structures of the silica can be created by transcription of left- and right-handed structures of the organogels 1+2 (R enantiomer) and 3+4 (S enantiomer), respectively. In addition, in the mixture systems of urea- and amide-based organogels, the right- and left-handed structures of the organogels 5+2 (R enantiomer) and 6+4 (S enantiomer) were precisely transcribed into the silica structure. The findings suggest that the sol-gel polycondensation proceeds along the surface of the helical structure of the organogels. We therefore believe that the sol-gel polycondensation by means of molecular assembly templates abundantly built in the organogel phase is a new strategy to create superstructured silica materials.

Journal Article↗