812-72-6Relevant articles and documents
Spontaneous polymer thin film assembly and organization using mutually immiscible side chains
Sun,Castner,Mao,Wang,McKeown,Grainger
, p. 1856 - 1866 (1996)
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 ?, 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)63- 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.
Dynamic contact angle studies of self-assembled thin films from fluorinated alkyltrichlorosilanes
Pellerite, Mark J.,Wood, Erika J.,Jones, Vivian W.
, p. 4746 - 4754 (2007/10/03)
Dynamic contact angle studies on self-assembled thin films from C7F15CH2OCH2CH2CH2 SiCl3 reveal a range of interesting behavior. Solution-based processing conditions have been identified that allow preparation of essentially monolayer films on quartz exhibiting water adv/rec contact angles of 119/104 ?± 2?° and extremely low contact angle hysteresis (hexadecane adv/rec = 74/70?°, heptane adv/rec = 56/55?°) with hydrocarbon liquids. This compound provides an example of a fluorinated trichlorosilane that is able to deliver low-hysteresis films by deposition at room temperature. Adsorption of silane oligomers, formed by hydrolysis and condensation reactions in solution, was also found to occur, slower than but competitive with monolayer formation. This process became more significant as dip coating times increased. Ellipsometric data on silicon wafers confirmed that film thicknesses increased with dip time, while AFM imaging showed that the oligomeric material was deposited in the form of particulates. The effects of this process on water dynamic contact angles are discussed. We also compare contact angles on these films with those on films prepared from CnF2n+1CH2CH2SiCl3 (n = 6, 8, 10) and draw some conclusions regarding structure-property effects in these systems. Finally, we propose a mechanism that can account qualitatively for the bulk of the results observed here. Its central feature is reaction of the fluorinated alkyltrichlorosilane with surface-adsorbed water to yield a self-assembled monolayer consisting of silanetriol molecules hydrogen-bonded to the substrate. Effects of high humidity aging on dynamic contact angles of these films suggest that they are at most only lightly cross-linked when prepared under conditions utilized here.
