Monomolecular layers and thin films of silane coupling agents by vapor-phase adsorption on oxidized aluminum

Abstract

Thin films of tetraethoxysilane [TEOS], (3-bromopropyl)trimethoxysilane [BPS], trimethoxyvinylsilane [VS], and 3-(trimethoxysily1)propyl methacrylate [TPM] on oxidized aluminum surfaces have been investigated by reflection-absorption FTIR spectroscopy, ellipsometry, contact angle, and quartz crystal microbalance (QCM) measurements. Gravimetric measurements with the QCM can reveal quantitative aspects of adsorption and film formation, even for films as thin as monolayers. Adsorption of these silane coupling agents from solution typically produces multilayer films. Vapor-phase adsorption of TEOS and TPM at room temperature results in monomolecular layers. The coupling agents VS and BPS require additional heating after the vapor-phase adsorption to initiate the hydrolysis and condensation reactions necessary for the surface attachment, which produces one to three layers. For vapor adsorbed films a packing density of 4-7 molecules/nm2 was found. The data strongly suggest that the organic moieties in several of these films have a preferential orientation on the surface; they can be viewed as two-dimensional, oligomeric siloxane networks with oriented organic chains. Subsequent heating of TPM films results in structural rearrangements; heating of TEOS results in complete condensation to Si02 films.

Organic overlayer model of a dental composite analyzed by laser desorption postionization mass spectrometry and photoemission

“…The methacryloyl overlayer morphology is modeled through analysis of the Si 2s peak energy loss structure as an overlayer with an exponentially decaying Si content from 33% at the SiO 2 interface to 1% at the air interface with a decay length at 1.6 nm. The 1.6 nm decay length slightly exceeds the ∼1.2 nm extended molecular chain of MPS 29. Overall, this modeled morphology is consistent with the presence of a one to two layer thick methacryloyl overlayer on the SiO 2 surface with the Si end bound to the oxide.…”

Distributed feedback grating fabricated from hybrid polymer precursor gel by employing short‐pulse laser interference for photopumped polymer laser applications

“…Therefore, the FTIR and NMR spectroscopies were employed to clarify the chemical bonds formed in the resulted precursor gels and hybrid polymers, which were prepared with rather different compositions and environmental conditions compared with the other previous works reported in the literature. The FTIR spectrum of TMSPMA monomer shows major absorption bands located at ν = ~800 and ~1090 cm −1 , which are attributed to Si―O―CH 3 vibrations . Figure shows the FTIR spectra of the precursor gel spin casted on a silicon substrate before and after photopolymerization.…”

“…The FTIR spectrum of TMSPMA monomer shows major absorption bands located at n=~800 and 1090cm À1 , which are attributed to Si-O-CH 3 vibrations. [21][22][23] Figure 2 shows the FTIR spectra of the precursor gel spin casted on a silicon substrate before and after photopolymerization. Photopolymerization was carried out by irradiation with an Hg lamp for 1min and then followed by post-baking.…”

Rheological and surface chemical characterization of alkoxysilane treated, fine aluminum powders showing enhanced flowability and fluidization behavior for delivery applications

“…This reaction produces additional ethanol molecules after the surface reactions occur as shown in Eqs. (2a), (2b) [26]. Alkoxysilanes are also less air reactive and have lower toxicity.…”