Formation of multilayers by self-assembly

Abstract

Monolayer and multilayer films were formed by self-assembly of methyl 23-(trichlorosilyl)tricosanoate (1) from organic solution. In agreement with published results, this compound was found to form good quality, close-packed monolayers on silicon surfaces. We have, however, found that films significantly thicker than the three monolayers previously obtained can be formed from continued chemisorption of monolayers of this compound followed by reduction of the surface ester with LiAlH4 in THF to form an "alcohol surface". The quality of monolayer formation in the multilayer films was monitored in detail by ellipsometry, contact angle, and FTIR measurements, and, although generally increasing disorder can be detected, films of up to 25 discrete monolayers can be successfully made. These results indicate that self-assembly is a viable alternative to the Langmuir-Blodgett transfer technique for the construction of relatively thick (O.l-gm scale), ordered, multilayer films.

Wet chemical routes to the assembly of organic monolayers on silicon surfaces via the formation of Si–C bonds: surface preparation, passivation and functionalization

“…pSi-RC(O)NHS). Very high yields for the activation reaction were found for a restricted range of NHS and EDC concentrations and molar ratios (5 …”

“…Namely, there was an inhomogeneous in-plane distribution of surface active sites and poorly defined polymerised material among the reaction products. 5 Further, the silicon-oxygen bonds that are formed tend to be prone to hydrolysis, especially under basic conditions, and thermal degradation of the structure has been reported. 6 Despite their intrinsic limitations, silane layers (Si-O-SiR) gave researchers a novel tool to modify surfaces with unprecedented control.…”

Designer solids and surfaces

“…While only two or three layers could be grown before structural defects in the film became important, this work laid the conceptual foundation for later, more successful systems. Tillman et al recently used an analogous technique in which the terminal group was a protected carboxylic acid rather than an olefin (33 an ordered multilayer film which adopts the well-known Zr(03PR)~ structure (Fig. 4) is produced (34).…”

Surface treatment and characterization: Perspectives to electrophoresis and lab‐on‐chips

“…Maoz and Sagiv [99] also found that high concentrations lead to disordered monolayers. Surprisingly, some scientists did not hesitate to put a few drops of water in their silane solution prior to the deposition [100]. As a consequence, Ulman et al [100,101] had to scrub their samples with detergent and a soft camel hairbrush to remove gel aggregates.…”

“…Surprisingly, some scientists did not hesitate to put a few drops of water in their silane solution prior to the deposition [100]. As a consequence, Ulman et al [100,101] had to scrub their samples with detergent and a soft camel hairbrush to remove gel aggregates. The water in the solvent is in equilibrium with the surface water from the substrate [102].…”