Adsorption of alkyl-trichlorosilanes on glass and silicon: a comparative study using sum-frequency spectroscopy and XPS

Löbau, J.; Rumphorst, A; Galla, K.; Seeger, Stefan; Wolfrum, K.

doi:10.1016/s0040-6090(96)08925-0

Cited by 22 publications

(11 citation statements)

References 45 publications

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“…In doing so, it is easier to compare our results with those obtained by others, as well as those of different reaction conditions. Unlike SFG studies of alkanethiol SAMs on gold substrates in which surface coverage can be estimated from the nonresonant SFG substrate signal, surface coverage of OTS on fused silica is not readily available from SFG because the nonresonant substrate signal is very weak …”

Section: Resultsmentioning

confidence: 99%

A Study of Alkyl Chain Conformational Changes in Self-Assembled n-Octadecyltrichlorosilane Monolayers on Fused Silica Surfaces

2001

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The adsorption and conformational changes of n-octadecyltrichlorosilane (OTS) self-assembled monolayers on fused silica surfaces are monitored by a nonlinear optical technique, sum-frequency generation (SFG) spectroscopy, and lateral force microscopy (LFM). The effect of a small amount of water in the OTS deposition solution on the alkyl chain conformation within the resulting OTS monolayers is also investigated. Results show that the alkyl chain conformational changes of OTS films on the surface of fused silica occur in three stages. The initial stage involves OTS adsorption from solution and the beginning of island formation. During this stage, the alkyl chains within the film are almost completely disordered, though a significant increase in surface coverage occurs. The second stage shows dramatic changes in alkyl chain conformation within the film from disordered gauche conformation to an ordered mainly all-trans conformation, while only a small increase in surface coverage occurs. The final stage is a much slower adsorption process. Although the surface coverage increases from 90% to a complete monolayer, only a slight increase in the SFG band intensities is observed during this stage. The early stages of OTS adsorption and the kinetic effect of water in the solvent on the resulting OTS monolayers are also studied by LFM. Island structures are observed, and the correlation of SFG, LFM, and contact angle measurements suggests that both uniform growth (monomer deposition) and island growth (aggregate deposition) occur during the OTS adsorption. The effect that water in the deposition solution has on each of these mechanisms is discussed.

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Section: Resultsmentioning

confidence: 99%

A Study of Alkyl Chain Conformational Changes in Self-Assembled n-Octadecyltrichlorosilane Monolayers on Fused Silica Surfaces

2001

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“…51 125°C/7.5 mmHg), in yields of typically 70-85%. NMR (in CDCl 3 ): 1 H, δ 1.5 (m, 2H); δ 1.9 (m, 2H); δ 3.6 (t, J ) 6 Hz, 2H); δ 3.9 (t, J ) 14 Hz, 2H); 13 Trichloro-1H,1H,2H,2H-perfluorododecylsilane, C 10 F 21 CH 2 -CH 2 SiCl 3 . A screw-top vial equipped for magnetic stirring was charged with 5.46 g of 1H,1H,2H-perfluoro-1-dodecene (C 10 F 21 CHdCH 2 , 0.01 mol), 0.38 g of 1 wt % solution of bis-(divinyltetramethyldisiloxane)Pt(0) in dichloromethane, and 1.59 g (0.012 mol) of trichlorosilane.…”

Section: Methodsmentioning

confidence: 99%

Dynamic Contact Angle Studies of Self-Assembled Thin Films from Fluorinated Alkyltrichlorosilanes

2002

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Dynamic contact angle studies on self-assembled thin films from C 7 F 15 CH 2 OCH 2 CH 2 CH 2 SiCl 3 reveal a range of interesting behavior. Solution-based processing conditions have been identified that allow preparation of essentially monolayer films on quartz exhibiting water adv/rec contact angles of 119/104 ( 2°and extremely low contact angle hysteresis (hexadecane adv/rec ) 74/70°, heptane adv/rec ) 56/55°) with hydrocarbon liquids. This compound provides an example of a fluorinated trichlorosilane that is able to deliver lowhysteresis films by deposition at room temperature. Adsorption of silane oligomers, formed by hydrolysis and condensation reactions in solution, was also found to occur, slower than but competitive with monolayer formation. This process became more significant as dip coating times increased. Ellipsometric data on silicon wafers confirmed that film thicknesses increased with dip time, while AFM imaging showed that the oligomeric material was deposited in the form of particulates. The effects of this process on water dynamic contact angles are discussed. We also compare contact angles on these films with those on films prepared from C n F 2n+1 CH 2 CH 2 SiCl 3 (n ) 6, 8, 10) and draw some conclusions regarding structure-property effects in these systems. Finally, we propose a mechanism that can account qualitatively for the bulk of the results observed here. Its central feature is reaction of the fluorinated alkyltrichlorosilane with surface-adsorbed water to yield a self-assembled monolayer consisting of silanetriol molecules hydrogen-bonded to the substrate. Effects of high humidity aging on dynamic contact angles of these films suggest that they are at most only lightly cross-linked when prepared under conditions utilized here.

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“…[40][41][42][43] Three additional frequency components at 2849, 2918, and 2970 cm −1 have been assigned to the symmetric (d + ) and antisymmetric (d − (π )) stretch of the methylene, and antisymmetric stretch of the methyl (r − ) groups. [40][41][42][43] Three additional frequency components at 2849, 2918, and 2970 cm −1 have been assigned to the symmetric (d + ) and antisymmetric (d − (π )) stretch of the methylene, and antisymmetric stretch of the methyl (r − ) groups.…”

Section: B Assignment Of Peaksmentioning

confidence: 99%

Ultrafast vibrational dynamics and spectroscopy of a siloxane self-assembled monolayer

Nihonyanagi

Eftekhari-Bafrooei

Borguet

2011

The Journal of Chemical Physics

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Time and frequency domain sum-frequency generation (SFG) were combined to study the dynamics and structure of self-assembled monolayers (SAMs) on a fused silica surface. SFG-free induction decay (SFG-FID) of octadecylsilane SAM in the CH stretching region shows a relatively long time scale oscillation that reveals that six vibrational modes are involved in the response of the system. Five of the modes have commonly been used for the fitting of SFG spectra in the CH stretching region, namely the symmetric stretch and Fermi resonance of the methyl group, the antisymmetric stretch of the methyl, as well as the symmetric and antisymmetric stretches of the methylene group. The assignment of the sixth mode to the terminal CH(2) group was confirmed by performing a density function theory calculation. The SFG-FID measures the vibrational dephasing time (T(2)) of each of the modes, including a specific CH(2) group within the SAM, the terminal CH(2), which had never been measured before. The relatively long (∼1.3 ps) dephasing of the terminal CH(2) suggests that alkyl monolayer structure is close to that of the liquid condensed phase of Langmuir Blodgett films.

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Adsorption of alkyl-trichlorosilanes on glass and silicon: a comparative study using sum-frequency spectroscopy and XPS

Cited by 22 publications

References 45 publications

A Study of Alkyl Chain Conformational Changes in Self-Assembled n-Octadecyltrichlorosilane Monolayers on Fused Silica Surfaces

A Study of Alkyl Chain Conformational Changes in Self-Assembled n-Octadecyltrichlorosilane Monolayers on Fused Silica Surfaces

Dynamic Contact Angle Studies of Self-Assembled Thin Films from Fluorinated Alkyltrichlorosilanes

Ultrafast vibrational dynamics and spectroscopy of a siloxane self-assembled monolayer

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