Spontaneous Polymer Thin Film Assembly and Organization Using Mutually Immiscible Side Chains

Abstract

Polymer ultrathin film self-assembly and organization on solid substrates has been directed using grafted siloxane copolymers bearing mutually immiscible alkyl and perfluoroalkyl side chains. Polysiloxanes grafted with both alkyl disulfide and perfluoroalkyl side chains have been synthesized and characterized. These terpolymer systems assemble spontaneously on gold surfaces, forming bound polymeric monolayers organized by intramolecular phase separation. Interfacially bound polymer monolayer fabrication is driven by multipoint alkyl disulfide side chain chemisorption to gold surfaces from dilute organic solution. Immiscible perfluoroalkyl side chains of low interfacial energy enrich the ambient-exposed outer regions of these monolayers, yielding a novel bound polymer monolayer with an anisotropic, layered structure and perfluorinated surface properties. Ellipsometry indicates that these polymer films have thicknesses ranging from 22 to 32 Å, depending on solution conditions and chemistry. Angular-dependent X-ray photoelectron spectroscopy has provided a depth profile of the bound polymer films, detailing the anisotropic composition resulting from perfluoroalkyl surface enrichment. Static secondary ion mass spectrometry measurements support the enrichment of perfluoroalkyl groups in the outer atomic levels of these films. Cyclic voltammetry using the redox probes Fe(CN) 6 3-and methylviologen with film-coated gold electrodes evaluated film-attenuated electron transfer. Time-of-flight secondary ion mass spectrometry has been used to image micropatterned polymer surfaces lithographed at high resolution both before and after organic monolayer assembly. Qualitative and quantitative information on film spatial organization and surface chemistry distribution on microstructures was obtained.

Electrochemistry at gold nanoparticles deposited on dendrimers assemblies adsorbed onto gold and platinum surfaces

“…Note the changes of vertical and horizontal scales between (A) and (B, C). dentate metal-ion ligand chemistry, stabilize the amine/gold interaction [40][41][42].…”

Synthesis and surface properties of semi-interpenetrating fluorine-containing polyacrylate and epoxy resin networks

“…The higher the hydrophobicity of film surface is, the higher the contact angle is. As mentioned before, the fluorine-containing polymers have good hydrophobic property and fluorine atoms have a strong tendency to spread to and locate on the film surface during the film formation [12][13][14]. Hence, when cured to form films, it is expected that the fluorine-containing groups in the FPAER-SIPNs tend to move towards the film surface, and consequently impart the surface hydrophobic function to some extent (Fig.…”

“…In fact, a conventional commodity polymer with a thin layer of perfluorinated groups rich in surface might achieve excellent surface properties. It is well known that the fluorinated groups, especially the pendant -CF 3 end groups on the perfluoroalkyl groups, have the tendency to migrate toward and preferentially locate at the outermost layer of the polymer-air interface to minimize the interfacial energy [12][13][14]. Consequently, the incorporation of the fluorinated groups into a suitable organic medium can not only decrease the cost of manufacturing fluorinecontaining polymer, but also get a fluorinated surface on a cheaper bulk organic film with excellent surface properties.…”

Selective immobilization of biomolecules onto an activated polymeric adlayer

“…[17][18][19][20][21][22] In particular, the covalent attachment for irreversible grafting can be accomplished by either "grafting-onto" [17][18][19] or "grafting-from" approach. [20][21][22][23] The grafting-from approach, surface-initiated polymerization, is a reliable method to achieve tunable and robust polymer brushes and to control their grafting density a͒ Author to whom correspondence should be addressed.…”