sil an ization

8/11/2019 Sil an Ization

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Surface silanization

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Metal or metal alkoxidesSol-gel processes

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Rate constant for acid-catalyzed hydrolysis of alkoxysilanes

according to the alkyl chain length and ramification20C

6R. Aelion et al., J. Am. Chem. Soc.1950, 72, 5705


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Base-catalyzed hydrolysis of alkoxysilanes

7C.J. Brinker, J. Non-Cryst. Solids 1988, 100, 31


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Inductive effect of sustituent of alkoxysilanes

9C.J. Brinker, J. Non-Cryst. Solids 1988, 100, 31


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!ifferent path"ays oforganosilanes grafting onhydroxylated surfaces

10A. Y. Fadeev et al. Langmuir 2000, 16, 7268


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Hydrolysis of functionalizedsiloxanes at a surface

F. Rondelez et al. Langmuir 1994, 10, 436711


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#xperimental setup for a surface silanization



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$rafting of n-hexadecyltrichlorosilane %n & '() on silicon oxide

Surface tension against cosine of thecontact angle of 3 different alkanedrops (octane, nonane and decane)for three silane layers prepared atdifferent temperatures


Critical surface tension (for cos = 1)against preparation temperature


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*ransmission infrared spectroscopy of surface grafted alkyl chains

ontemperatu

re,

C

F. Rondelez et al. J. Phys. Chem. 1994, 98(31), 758114

prepar

at

C-H stretching of CH2 and CH3

Asymetric CH2stretching moves from 2917 to 2922 cm-1 on temperature increase


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Analysis y Infrared spectroscopy

After grafting on TiO2

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C18H37SiH3

H2O stretchingH2O deformation

H2O linked tosurface oxygen Siloxanes

CH2 CH2SiH SiH

A.-Y. Fadeev et al. Langmuir 2004, 126, 7595


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+,Si MR spectra of self-assemled polyalkylsiloxane layers

TiO2

Al2O3

MgO

Substrate

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Si-O-Si

Reference compounds

M-O-Si

The polysiloxane network is not linked to the oxide surface


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.roposed mechanism for gro"th of self-assemled polyalkylsiloxane monolayer

1 2

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1. Acid or basic catalytic hydrolysis of the silicon hydride2. Polycondensation of the silanol bonds

Reaction of silicon hydride depends on the catalytic activity of the surfaceand so leads selectively to a monolayer


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Silanization can lead to loosely grafted structures

22J.-P. Pillot et al. Langmuir 2009, 25, 5526


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$rafting of aminoalkylsilanes

The most commonly used reactive molecule :

Aminopropyltriethoxysilane, APTES

a) Ideal surface structure

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b) Actual surface structure asdeduced from XPS N1sspectroscopy

c) X-ray Photoelectron

Spectroscopy of a graftedsurface, in green : theexpected NH2 signal

C-NH3+

L. Ploux et al. J. Phys. Chem. C 2011, 115, 11102


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$rafting of epoxyalkylsilanes

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$rafting of mercaptoalkylsilanes

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$rafting of an enzyme

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Heteroifunctional linker

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/ther methods for coupling enzymes

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Biocidal cationic surfaces

30F. Rondelez et al. Microbiology 2005, 151, 1341


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Biocidal cationic surfaces

E. coli

The viable bacteria are green

31F. Rondelez et al. Microbiology 2005, 151, 1341

S. epidermitis

sil an ization

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