TEOS hybrid coatings

Figure 4.21 Atomic force microscopy images showing the morphology of coloured Si02-PMM A hybrid coatings with molar ratio formulation of 1 0.5 1.0 TEOS-TMSPM MMA, with different concentrations and types of colour (a) no colour (b) 0.17 wt% of blue colour (c) 0.83 wt% of green colour. The values of the r.m.s. average roughness measured for the three films was 0.47, 0.65 and 0.45 nm, respectively. (Reproduced from ref. 21, with permission.)...

Figure 19-13. Bode plot alter 200 h of electrochemical attack for Si02 (from TEOS) inorganic coatings (550 nm) and SiOi (from TEOS/MTES) hybrid coatings (600 and 1400 nm) (Galliano, 1998).

Furthermore, cross-linking of the matrix and mechanical properties (such as E and H) can be improved when in situ silica particles are formed, by adding fully hydrolyzable precursors (mainly TEOS) to the hybrid coating during the hydrolysis and condensation reactions of the hybrid silica matrix [42]. 

Figure 4-7. Evolution of FTIR spectra for coatings prepared from TEOS (IS) and MTES/TEOS (HS) at normal incidence, for different heat treatment temperatures. (Reprinted from Journal of Non-Crystalline Solids, 298, J. Gallardo, A. Duran, D. Di Martino, R.M. Almeida, Structure of inorganic and hybrid Si02 sol-gel coatings studied by variable incidence infrared spectroscopy , p. 220, Copyright (2002), with permission from Elsevier.)...

Figure 26-8. Surface morphology of the amino-functionalized hybrid sol/gel coatings with TEOS APS ratio of (a) 3 1, and (b) 1 3. The RMS surface roughness values are 3 and 40 A, respectively.

A silica-fluoride hybrid matrix improves the scratch resistance, abrasive resistance, fingerprint resistance, water-proof properties and refractive index of the coating. This hybrid is obtained by hydrolysis and condensation of tetraethoxysilane (TEOS) and 1,6-bis-(trimethoxysirilethyl)dodecafluorohexane (TMFH) as shown in Figure 34-13. TMFH is one of the most suitable fluoride compounds which can promote the reliability for practical use in combination with TEOS. TMFH has methoxy groups at the end of the... 

Electrodeposited sol-gel-based composite films also showed optical applications. Gu and coworkers [85,86] co-electrodeposited Te0 > -Si02 hybrid films from the TEOS-Te(i-PrO)4 niixed precursor for nonlinear optics. Te(IV) was partially reduced during electrodeposition, as characterized by EDX of the obtained films. The as-prepared films had third-order nonlinear susceptibility ix ) of 5.9 X10 to 4.29 X 10 esu, and the films had of 1.551 X 10 esu after posttreatment annealing. Mandler and coworkers co-electrodeposited TMOS with multiwalled carbon nanotubes (MWCNTs) on ITO and silver. The optimized films electrodeposited on ITO showed transparency of about 50% with nonlinear optical properties, and the optimized films electrodeposited on silver had specular reflectance lower than 0.5% in the wavelength range of 400-15 000 nm, which can be used as antireflection coatings. 

Monodisperse nanoparticles can be easily coated with silica shells to create hybrid ferrite Si02 core-shell NPs by the Stober process (using hydrolyzed tetraethyl orthosiUcate (TEOS)) or by a microemulsion process (Figure 26.2). This process can be carried out in the presence of a surfactant such as cetyltrimethy-lammonium bromide (CTAB) or Triton X-100 to produce ordered mesoporous silica or by using sodium silicate as precursor in water and basic pH [9,17]. 

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