Characterization of monolayers and LB films of octadecyltrialkoxysilanes

Taylor, David; Gupta, Sandeep; Dynarowicz, Patrycja

doi:10.1016/s0040-6090(95)08276-x

Cited by 11 publications

(20 citation statements)

References 9 publications

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“…The plateau near 11 mN/m corresponds to a liquid expanded to condensed (LE-LC) phase transition while the plateau at 20 mN/m has been attributed to an undulation effect. 7 This effect is also referred to as a liquid condensed to solid condensed (LC-SC) phase transition in which adjacent methoxy groups assume a staggered conformation. The disappearance of these plateaus with time is an indication that methoxy groups are being replaced with hydroxy groups.…”

Section: Protonation and Hydrolysismentioning

confidence: 99%

Protonation, Hydrolysis, and Condensation of Mono- and Trifunctional Silanes at the Air/Water Interface

Britt

Hlady

1999

Langmuir

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The protonation, hydrolysis, and condensation kinetics of octadecyldimethylmethoxysilane (OMMS) and octadecyltrimethoxysilane (OTMS) at the air/water interface were investigated using a monolayer trough. OTMS chemical condensation within physically condensed phases was observed in transferred monolayers using fluorescence microscopy. Molecular area increases and decreases attributed to protonation and hydrolysis, respectively, of silane methoxy groups were measured by a surface balance. These area changes at constant surface pressure suggested a stepwise protonation and hydrolysis of the three OTMS methoxy groups. In contrast, only a single protonation and hydrolysis event was observed for monofunctional OMMS. The influences of monolayer spreading time, silane packing density, and subphase pH on the reaction kinetics are presented.

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Section: Protonation and Hydrolysismentioning

confidence: 99%

Protonation, Hydrolysis, and Condensation of Mono- and Trifunctional Silanes at the Air/Water Interface

Britt

Hlady

1999

Langmuir

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“…The shape of the isotherm acquired on the water subphase is typical of ODTMS film over a wide pH range (4.8–10.3) 9c. d, k, 10 Four distinct phases are noted in Figure 1 and interpreted by the phase transitions detailed in the above references. The end point of these phases differ by a few Å 2 per molecule between different studies, but this can be attributed to impurities, the aging of the ODTMS solution, its water content, and the resulting degree of hydrolysis of ODTMS.…”

Section: Resultsmentioning

confidence: 91%

“…It is known that the shape of the isotherm strongly depends on the conditions, such as temperature, pH, and compression rate 9k. Therefore, the π –A isotherm of ODTMS Langmuir film at the water–electrolyte interface is slightly different (Figure 1, black line) than that recorded with pure water.…”

Section: Resultsmentioning

confidence: 92%

In Situ Electrodeposition of an Asymmetric Sol–Gel Membrane Based on an Octadecyltrimethoxysilane Langmuir Film

Hitrik¹,

Lev²,

Mandler³

2014

Chemistry A European J

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The unique properties of Langmuir film formation were utilized in assembling a thin skin of an asymmetric membrane. An octadecyltrimethoxysilane (ODTMS) Langmuir monolayer was formed at the air-water interface and served as the substrate for growing a bulky sol-gel polymer in situ. The latter was based on the electrochemical deposition of tetramethoxysilane dissolved in the water subphase by means of horizontal touch electrochemistry. The resultant asymmetric layer that consisted of a thin hydrophobic ODTMS Langmuir film connected to a bulk hydrophilic sol-gel network was studied in situ and ex situ by using various techniques, such as cyclic voltammetry, electrochemical impedance spectroscopy (EIS), scanning electron microscopy, transmission electron microscopy (TEM), and goniometry. We found that a porous hydrophilic film grew on top of a hydrophobic layer as was evident from TEM, contact angle, and EIS analyses. The film thickness and film permeability could be controlled by changing the deposition conditions such as the potential window applied and its duration. Hence, this method offers an alternative approach for assembling asymmetric films for various applications.

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“…At much smaller mean molecular area (MMA) and around P ¼ 22 mN Á m À1 , another plateau appears where the methoxy groups are assumed to stagger to minimized the molecular area. [22] This feature is then followed by a slowly sloping region which can only be attributed to the ultimate collapse of the monolayer because of the particularly small mean molecular area in this region.…”

Section: Isothermsmentioning

confidence: 99%

Interfacial Behavior of a Reacting Alkoxysilane Monolayer System

Carino

Duran

2004

Macro Chemistry & Physics

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Summary: We report here the results on the investigations of the dynamic interfacial behavior of a trifunctional alkoxysilane, octadecyltrimethoxysilane (OTMS) as it is reacting at the air‐water interface. We have investigated both the Π‐A isotherms and A(t) isobars of OTMS at acidic subphases. An attempt to analyze the kinetics of the reaction in the monolayer was limited to the early stages of the reactions and only describes the kinetics of hydrolysis. We also confirmed by rheological measurements that this system does indeed form a network inefficiently and the resulting structure most likely consists of extensive linear segments as has been suggested in earlier reports. The general rheological characteristic indicates the product to have high molecular weight. The product also exhibited a 2D sol‐gel transition that has general features of a percolating network. However, the scaling behavior does not follow exactly that predicted; several reasons for this are discussed.A(t) isobars of OTMS at various subphase pHmagnified imageA(t) isobars of OTMS at various subphase pH

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Characterization of monolayers and LB films of octadecyltrialkoxysilanes

Cited by 11 publications

References 9 publications

Protonation, Hydrolysis, and Condensation of Mono- and Trifunctional Silanes at the Air/Water Interface

Protonation, Hydrolysis, and Condensation of Mono- and Trifunctional Silanes at the Air/Water Interface

In Situ Electrodeposition of an Asymmetric Sol–Gel Membrane Based on an Octadecyltrimethoxysilane Langmuir Film

Interfacial Behavior of a Reacting Alkoxysilane Monolayer System

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