Gold-thiol monolayers polymeric

Polymerized diacetylenes show remarkably improved stability as compared to monomeric gold-thiol monolayers (see Section VI). 

A similar although not topochemieally governed ap-proaeh to polymerize thiol-bearing monomers has been recently reported using mercaptomethyl styrene monomer [26]. Assembly of the monomer into dense-paeked mono-layers on gold is followed by free radical- or photo-induced polymerization in situ. Presence of httle residual monomer or ohgomer by mass spectrometry supports other speetroseopie evidence for monolayer polymerization. 

Patterns of ordered molecular islands surrounded by disordered molecules are common in Langmuir layers, where even in zero surface pressure molecules self-organize at the air—water interface. The difference between the two systems is that in SAMs of trichlorosilanes the island is comprised of polymerized surfactants, and therefore the mobihty of individual molecules is restricted. This lack of mobihty is probably the principal reason why SAMs of alkyltrichlorosilanes are less ordered than, for example, fatty acids on AgO, or thiols on gold. The coupling of polymerization and surface anchoring is a primary source of the reproducibihty problems. Small differences in water content and in surface Si—OH group concentration may result in a significant difference in monolayer quahty. Alkyl silanes remain, however, ideal materials for surface modification and functionalization apphcations, eg, as adhesion promoters (166—168) and boundary lubricants (169—171). 

A sensitive mediatorless sensor of H2O2. Gold electrode was immersed in thiol-functionalized poly(styrene-co-acrylic acid) (St-co-AA) nanosphere latex prepared by emulsifier-free emulsion polymerization of St with AA and functionalized with dithioglycol to assemble the nanospheres. Then, GNPs were chemisorbed onto the thiol groups and formed monolayers on the surface of poly(St-co-AA) nanospheres. Finally, horseradish peroxidase was immobilized on the surface of the GNPs Polymer terminated by 2-(2,4-... 

The earliest, and also the most widely studied, SAM systems are those formed by the adsorption of alkyl-siloxanes onto silicon dioxide and by the adsorption of thiols onto noble metal surfaces (Ref. 11 is an extensive review of the subject), but many other SAM systems have been reported. Besides gold, alkanethiols also form ordered, close-packed monolayers on the surfaces of a number of noble metals (including Ag, Cu, Pd, and Pt) and on GaAs, while alkylphosphonic acids and carboxylic acids form SAMs on oxide surfaces. Siloxane monolayers are the most stable, utilizing strong, covalent interactions (Si-O-Si linkages) to tether the molecules to a silanol-terminated oxide surface. However, the chemistry of interaction between the adsorbates and the surface is complex. Silanes (RSiCb) and alkoxysilanes (RSiORj) tend to self-polymerize, which confers additional stability on the... 

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