The sol-gel process

Hench, Larry L.; West, Jon K.

doi:10.1021/cr00099a003

Cited by 4,109 publications

(2,556 citation statements)

References 62 publications

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“…In aqueous systems, metal alkoxides are the most widely used precursors, and their chemical transformation into the oxidic network involves hydrolysis and condensation reactions. 5 In aqueous solgel processes, the oxygen for the formation of the oxidic compound is supplied by the water molecules. In nonaqueous systems, where intrinsically no water is present, the question of the origin of the oxygen for the metal oxide arises.…”

Section: Nonaqueous Sol-gel Chemistrymentioning

confidence: 99%

Nonaqueous Sol–Gel Routes to Metal Oxide Nanoparticles

2007

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Sol-gel routes to metal oxide nanoparticles in organic solvents under exclusion of water have become a versatile alternative to aqueous methods. In comparison to the complex aqueous chemistry, nonaqueous processes offer the possibility of better understanding and controlling the reaction pathways on a molecular level, enabling the synthesis of nanomaterials with high crystallinity and well-defined and uniform particle morphologies. The organic components strongly influence the composition, size, shape, and surface properties of the inorganic product, underlining the demand to understand the role of the organic species at all stages of these processes for the development of a rational synthesis strategy for inorganic nanomaterials.

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Section: Nonaqueous Sol-gel Chemistrymentioning

confidence: 99%

Nonaqueous Sol–Gel Routes to Metal Oxide Nanoparticles

2007

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“…The chemistry of the sol-gel process is well known [7][8][9] with excellent reviews [6,10,11] and books [12] available. The most common sol-gel materials used as coatings are based on organically modified silicates (Ormosils), which are formed by the hydrolysis and condensation of trialkoxy silanes precursors [13,14].…”

Section: Introductionmentioning

confidence: 99%

Corrosion protection of AA 2024-T3 aluminium alloys using 3, 4-diaminobenzoic acid chelated zirconium–silane hybrid sol–gels

Varma

Colreavy

Cassidy³

et al. 2010

Thin Solid Films

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Organic-inorganic polymers formed by hydrolysis/condensation reactions of alkoxide precursors, such as organically modified silanes (Ormosils) are used for several industrial applications such as electronic, optical and protective anticorrosion coatings. Such materials possess superior chemical stability, physical strength and scratch resistance characteristics when compared to organic polymers. Further performance improvement can be achieved through the incorporation of zirconium and titanium based nanoparticles, also formed through from precursors via the sol-gel process. However due to the inherent reactivity differences of the above precursors, they must be hydrolysed separately before being combined for final condensation. Zirconium precursors are commonly chelated using acetic acid or acetyl acetonate prior to hydrolysis, to lower the hydrolysis rate. In this body of work, 3,4-diaminobenzoic acid (DABA) and acetyl acetonate (acac) were compared as chelating ligands for controlling the hydrolysis reactions of zirconium n-propoxide to form nanoparticles within a silane sol matrix. The sols were applied as coatings on aerospace grade aluminium alloy AA 2024-T3 and characterised by physical, spectroscopical, microscopical, electrochemical and calorimetric techniques. The electrochemical properties of the coatings, as characterised by EIS and PDS, correlated with neutral salt spray evaluations confirming that the use of DABA as a chelating ligand significantly improved the coating performance when compared to the traditional diketone ligand. The data indicates the anticorrosion properties of the nitrogen rich chelate have a key role in protecting the alloy through the formation of smaller zirconium nanoparticles, thus improving the polymer network stability.

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“…It has been noted that the surface of the protein could also interact with or adsorb to the hydrophilic silica pore walls through electrostatic or hydrogen bonding interactions. 3,[23][24][25][26][27][28] Fluorescence anisotropy studies have demonstrated that proteins in sol-gel pores experience dramatically hindered rates of rotation due to protein adsorption to the pore walls. 23,29,30 Alternatively, the pore dimensions could influence the protein structural stability by affecting the dynamics of the surrounding solvent, which is intimately coupled to the dynamics of the protein.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Proteins Encapsulated in Silica Sol−Gel Glasses Studied with IR Vibrational Echo Spectroscopy

2006

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Spectrally-resolved infrared stimulated vibrational echo spectroscopy is used to measure the fast dynamics of heme-bound CO in carbonmonoxy-myoglobin (MbCO) and hemoglobin (HbCO) embedded in silica sol-gel glasses. On the time scale of ~100 fs to several ps, the vibrational dephasing of the heme-bound CO is measurably slower for both MbCO and HbCO relative to aqueous protein solutions. The fast structural dynamics of MbCO, as sensed by the heme-bound CO, are influenced more by the sol-gel environment than those of HbCO. Longer time scale structural dynamics (tens of ps), as measured by the extent of spectral diffusion, are the same for both proteins encapsulated in sol-gel glasses compared to aqueous solutions. A comparison of the sol-gel experimental results to viscosity dependent vibrational echo data taken on various mixtures of water and fructose shows that the sol-gel encapsulated MbCO exhibits dynamics that are the equivalent to the protein in a solution that is nearly 20 times more viscous than bulk water. In contrast, the HbCO dephasing in the sol-gel reflects only a 2-fold increase in viscosity. Attempts to alter the encapsulating pore size by varying the molar ratio of silane precursor to water (R-value) used to prepare the sol-gel glasses were found to have no effect on the fast or steady-state spectroscopic results. The vibrational echo data are discussed in the context of solvent confinement and protein-pore wall interactions to provide insights into the influence of a confined environment on the fast structural dynamics experienced by a biomolecule.

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The sol-gel process

Cited by 4,109 publications

References 62 publications

Nonaqueous Sol–Gel Routes to Metal Oxide Nanoparticles

Nonaqueous Sol–Gel Routes to Metal Oxide Nanoparticles

Corrosion protection of AA 2024-T3 aluminium alloys using 3, 4-diaminobenzoic acid chelated zirconium–silane hybrid sol–gels

Dynamics of Proteins Encapsulated in Silica Sol−Gel Glasses Studied with IR Vibrational Echo Spectroscopy

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