Comparative study of the sol–gel processes starting with different substituted Si-alkoxides

Jitianu, Andrei; Britchi, Alina Gabriela; Deleanu, Călin; Bădescu, Viorel; Zaharescu, Maria

doi:10.1016/s0022-3093(03)00007-3

Cited by 78 publications

(48 citation statements)

References 30 publications

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“…The NMR spectrum of the pure MTEOS precursor (Fig. 1) shows a single T 0 0 peak located at −44.03 ppm confirming the absence of any hydrolysed or modified regions respectively [15]. These bands are actually composed of several peaks indicating different degrees of hydrolysis for the silicon atom in each configuration, as summarised in Table 1.…”

Section: Resultsmentioning

confidence: 86%

“…At the higher temperature the sol-gel dried faster than at the lower temperature and a thermal treatment of the gels at 50-70 • C was high enough to allow the evaporation of water, organic solvents and other moisture contents. Crucially this temperature range is below the softening (deformation) temperature of the polypropylene microtitre plates and, therefore, was chosen Table 1 Assignments of 29 Si NMR signals for monomeric and oligomeric species obtained from the metal doped MTEOS sol-gel [15]. as the curing temperature of the sol-gel.…”

Section: Thermal Analysismentioning

confidence: 99%

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Preparation and rapid analysis of antibacterial silver, copper and zinc doped sol–gel surfaces

Jaiswal

McHale²,

Duffy

2012

Colloids and Surfaces B: Biointerfaces

140

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Section: Resultsmentioning

confidence: 86%

Section: Thermal Analysismentioning

confidence: 99%

Preparation and rapid analysis of antibacterial silver, copper and zinc doped sol–gel surfaces

Jaiswal

McHale²,

Duffy

2012

Colloids and Surfaces B: Biointerfaces

140

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“…In HCl-catalysed reactions, hydrolysis is faster than condensation (Devreux et al 1990;Meixner and Dyer 1999), and alkyl-substituted trialkoxysilanes hydrolyse faster than the corresponding tetraalkoxysilanes (Himmel et al 1990). In particular, MTEOS hydrolyses faster than the TEOS monomer during each sequential hydrolysis reaction (Fyfe and Aroca 1997;Jitianu et al 2003). The replacement of the acidic conditions of an alkoxy by non-hydrolysable radicals leads to higher hydrolysis rates because the inductive effect of these radicals lowers the positive charge on the silicon and increases the negative charge on the oxygen atoms around the silicon atom as compared with TEOS (Devreux et al 1990;Jitianu et al 2003).…”

Section: Resultsmentioning

confidence: 99%

“…In particular, MTEOS hydrolyses faster than the TEOS monomer during each sequential hydrolysis reaction (Fyfe and Aroca 1997;Jitianu et al 2003). The replacement of the acidic conditions of an alkoxy by non-hydrolysable radicals leads to higher hydrolysis rates because the inductive effect of these radicals lowers the positive charge on the silicon and increases the negative charge on the oxygen atoms around the silicon atom as compared with TEOS (Devreux et al 1990;Jitianu et al 2003). Due to the fast hydrolysis rate, the formation of siloxane bonds controls the condensation rate, which in acidic media increases as a logarithm of time.…”

Section: Resultsmentioning

confidence: 99%

Characterisation of hybrid xerogels synthesised in acid media using methyltriethoxysilane (MTEOS) and tetraethoxysilane (TEOS) as precursors

et al. 2011

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The mild synthetic conditions provided by the sol-gel process and the versatility of the colloidal state allow for the mixing of inorganic and organic components at the nanometre scale in virtually any ratio for the preparation of hybrid materials. Our interest in hybrid xerogels focuses on combining their porosity with other properties to prepare optic-fibre sensors. The specific aim of this paper is to synthesise hybrid xerogels in acid media using methyltriethoxysilane (MTEOS) and tetraethoxysilane (TEOS) as silica precursors and to investigate the effect of the MTEOS molar ratio on the structure and porous texture of xerogels. Gelation time exponentially increased as the MTEOS molar ratio increased. Increasing the MTEOS molar ratio yielded xerogels with lower density and lower particle size. The incorporation of MTEOS resulted in new FTIR bands at 1276 and 791 cm −1 , which was attributed to vibrational modes of methyl group. The band around 1092 cm −1 associated with siloxane bonds shifted to lower wavenumbers and split into two bands. The 29 Si spectra only showed the Q n (n = 2, 3, 4) signal in xerogels with 0% MTEOS and the T n (n = 2, 3) signal in xerogels with 100% MTEOS; hybrid xerogels showed both Q and T signals. From XRD peaks at 2θ around 9°, we inferred that xerogels (>70% MTEOS) consisted of nanocrystalline CH 3 -SiO 3/2 species. Increasing the MTEOS molar ratio produced xerogels with lower pore volumes and lower average pore size. The integration of methyl groups on the surface decreased the surface polarity and, in turn, the characteristic energy.

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“…The amount, position and intensity of the bands from organics, when resolved in reference to literature data, seems to be evidently connected with organic additives have been employed [9,13,14]. Bands at around 562-576 cm -1 from absorption of lithium in LiClO 4 and bonded to organics, are observed in the FTIR spectra of all the hybrid electrolytes obtained.…”

Section: Samplementioning

confidence: 62%

Li‐ion conducting organic‐inorganic hybrid electrolytes derived from TEOS and methacrylates

Żelazowska

Borczuch-Łączka

Rysiakiewicz-Pasek

2007

Phys. Status Solidi (c)

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Li-ion conductive organic-inorganic hybrid electrolytes with the ionic conductivities of 10 -3 -10 -2 Scm [3][4][5]. Higher ionic conductivities can usually be achieved by using additives of the small organic molecule plasticizer or synthesizing polymer gel electrolytes, but also results in decrease of mechanical stability, while cross-linked polymer electrolytes are mostly the typical glassy polymers with high brittleness [6][7][8][9]. In the last years, sol-gel derived organic-inorganic hybrids have attracted a great deal of attention for the solid electrolyte applications [10]. In this work, lithium salt doped organic -inorganic hybrid electrolytes based on TEOS and organic additives were investigated for morphology, structural properties and ionic conductivity with aim to determine their potential to be useful as transparent solid electrolytes for the room-temperature applications.

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Comparative study of the sol–gel processes starting with different substituted Si-alkoxides

Cited by 78 publications

References 30 publications

Preparation and rapid analysis of antibacterial silver, copper and zinc doped sol–gel surfaces

Preparation and rapid analysis of antibacterial silver, copper and zinc doped sol–gel surfaces

Characterisation of hybrid xerogels synthesised in acid media using methyltriethoxysilane (MTEOS) and tetraethoxysilane (TEOS) as precursors

Li‐ion conducting organic‐inorganic hybrid electrolytes derived from TEOS and methacrylates

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