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SEM micrographs of polyaniline-polymethylene patterns on gold. The dark region represents the polyaniline part and the lighter region represents the polymethylene part.
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Micrometer scale patterns of polymethylene film was prepared by selective formation of polymethylene on a gold surface patterned with an organothiol monolayer as the resist. The monolayer effectively retarded the gold-catalyzed polymerization reaction from diazomethane. The polymethylene film, in the thickness range of 300−400 Å, in turn serves as...
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... use of a dimer-aniline monolayer offers the possibility of selective polymerization by chemical oxidation. 38 Figure 9 presents the SEM micrographs of test samples of the polyaniline-polymethylene pattern in different magnifications. The lighter area represents the polym- ethylene-covered area and the darker area represents the polyaniline-covered area. ...
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Citations
... We have demonstrated the use of aniline dimer terminal alkanethiol monolayer modified gold substrate to generate polyaniline pattern in both chemical and electrochemical methods. It was found that the electrochemical polymerization of dimeraniline monolayer modified surface started at less oxidation potential than the potential required for oxidation aniline monolayer modified gold substrates [26]. ...
PANI–Ag nanocomposites were successfully synthesized by interfacial polymerization processes using aniline dimer (4-aminophenyldiphenylamine, APDA) as starting material in chloroform in contact with an aqueous solution of silver nitrate at different molar ratios. Synthesized PANI–Ag nanocomposites were characterized through various instrumental techniques. The electrocatalytic behavior of the nanocomposite was tested for the electrochemical oxidation of hydrazine.
... 6H 2 O were obtained from Merck, Germany. The ω-(N-pyrrolyl) undecanethiol (PyC 11 SH) was obtained from our previous work 30 . ...
... The fabrication of an elastomeric PDMS stamp was described in more detail in our previous investigation 30 . In brief, SYLGARD silicon elastomer 184 and SYLGARD silicon elastomer 184 curing agents were mixed in a 10 : 1 ratio and air bubble was removed from the mixture by vacuum. ...
... The stamp can be used for the generation of more than 100 patterns without loss of its features. Experimental detail of the scanning electron micrograph (SEM) was elaborated in our previous work 30 . ...
Micrometre-sized conducting polypyrrole pattern was generated on gold surface using microcontact printing (μ-CP) technique. ω-pyrrolyl undecanethiol was used as ink to print on gold surface with an elastomeric stamp. The patterned gold surface was then exposed to diazomethane solution in which the monomer acted as a resist for the selective growth of polymethylene on unmodified gold surface. The pyrrole terminal monolayer-patterned surface functioned as a monolayer for the chemical polymerization of pyrrole and the resulting formation of conducting polypyrrole pattern with submicron dimensions. The structural features of the patterned surface can be determined by optical microscopy, AFM and scanning electron micrograph.
A simple method is adopted to prepare conducting polyaniline thin film on cellulose filter paper by chemical oxidative polymerization. In order to improve the adhesion of polyaniline on cellulose nanofiber aniline terminal, silane monolayer was used as catalyst to initiate polymerization reaction. It was also showed that aniline dimer modified cellulose nanofiber shows an enhanced polyaniline growth and acting as seed for the polyaniline growth. The polyaniline modified cellulose fibre filter paper was then characterized with UV-visible spectroscopy, FT-IR, FE-SEM and electrochemical studies. Polyaniline modified filter paper strips can be used for naked eye sensing of ammonia and hydrazine in environmental samples
This scientific review aims to provide a comprehensive account of the use of N-heterocyclic carbine (NHC) and other carbenes as ligands for surfaces. Its main goal is to organize the literature and illuminate challenges, patterns, and paths forward in this nascent field. The review begins with a discussion of NHC stabilization of molecular elemental allotrope species, which represent the smallest possible fragments of a metal surface. It also describes examples of NHC ligands bound to nanoparticles (NPs) and moves to the formation of NHC monolayers on planar surfaces. It concludes with a summary of the application of other types of carbenes to surface stabilization.
In this paper, patterning ability of ultra-thin films of conducting polypyrrole deposited on silicon wafer surfaces by in situ chemical polymerization in the presence of different anionic dopants including α-naphthalene sulfonic acid, anthraquinone-2-sulfonic acid sodium salt monohydrate/5-sulfosalicylic acid dehydrate and camphor sulfonic acid has been studied. “Lift-off process” combined with photolithography is the used method for large-area and easy fabrication of micro patterns of conducting PPy thin films. In this procedure, a self-assembled mono layer of Py-silane is deposited on a patterned surface of a positive photoresist, followed by immersion of the surface into polymerization solution. After polymerization, positive micro pattern of the conducting PPy thin film appears on the surface by lifting-off the post baked positive photo resist by THF. The results showed deposition and patterning of conducting PPy thin films with nanometer thickness and relatively high range of conductivity with features as small as 3-4.5 µm in lateral dimensions on silicon wafer.
Self-assembled monolayers (SAMs) prepared by the adsorption of hexadecanethiol (C16SH) onto gold exhibit infrared and impedance spectra that are consistent with a greater overall chain density when prepared in aqueous micellar solutions of hexaethylene glycol monododecyl ether (C12E6) than when prepared in ethanol or isooctane, although the initial step of the assembly process is much slower in the micellar solution. On the basis of ex situ infrared spectra taken at different adsorption times, SAMs prepared in C12E6(aq) undergo a more thorough structural transformation to likely minimize collapsed chains and other defects within the film. These water-borne SAMs are greatly resistant to structural changes when immersed in blank solvents (C12E6(aq), ethanol, and isooctane), but changes in the IR spectra suggest that a small fraction of thiolate molecules desorb from the surface when exposed to a solution containing C16SH in ethanol. Conversely, when ethanolic SAMs are exposed to a solution of C16SH in C12E6(aq), changes in the IR spectra are consistent with a net adsorption of thiols to increase the adsorbate density. SAMs prepared in isooctane exhibit significantly less stable structures when exposed to blank solvents as compared to SAMs prepared in C12E6(aq) and ethanol. Combined, these results reveal that solvent−adsorbate and solvent−film interactions play an important role in defining the structure of a SAM and that the use of weaker solvents to prepare the SAMs yields more densely packed films with fewer defects that are more stable against desorption.
Two kinds of polymer brushes, the single one with stereospecific polyacrylamide (PAAM) chains and the dual-component one with random poly(methyl methacrylate) (PMMA) segments grafting from stereospecific PAAM chains, were prepared on silicon wafer for the first time by combining the immobilization of initiator and the stereospecific living radical in situ polymerization. With the addition of the Lewis acid AlCl3 into the polymerization system, the PAAM brushes obtained exhibited an increased stereospecificity as well as a decreased hydrophilicity, which might attribute to the reduced thickness of PAAM brushes on the silicon wafer and the handicap of the free rotation of the stereospecific molecular chain. The smoother surface morphology of the stereospecific PAAM brushes shown in AFM images was in good agreement with the experimental data of water contact angle. Also, block amphiphilic copolymer brushes were prepared with the stereospecific PAAM formed first on silicon wafer as the anchored-initiator and revealed a novel surface self-assembly behavior after being treated with different solvent such as toluene or water. The stereospecificity of PAAM chains in the polymer brushes could be modulated by adjusting reaction conditions according to the requirement of applications for surface hydrophilicity.
The research field of “Macromolecular chemistry” has changed considerably during the last 10 years. There has been unexpected break throughs in the area of bulk polymers despite the fact that research in this area could have been considered to be complete. The metallocene catalysts open up the synthesis of new polymer combinations with completely new structures. Their potential has not yet been exhausted. The trend toward building polymeric structures with small dimensions and to nanotechnology is decisive. Many workgroups within germany and abroad have been working on nano-particles and layers and with reactions at interfaces with respect to their technological and biochemical application. Evidently this trend has been promoted though the foundation of competence centers of nanotechnology. The following report for the year 1998 gives some information on these developments without claiming to be complete.
