Oxidative Graft Polymerization Of Aniline Research Articles

In situ chemical oxidative graft polymerization of aniline from phenylamine end-caped poly(ethylene glycol)-functionalized multi-walled carbon nanotubes

The aim of this study is the in situ chemical oxidative graft polymerization of aniline from phenylamine end-caped poly(ethylene glycol)-functionalized multi-walled carbon nanotubes.

Polyaniline In Situ Grafted to Graphene Sheets

Graphene is one of the most promising allotropes of carbon with wide applications in nanotechnology. Modification of graphene by chemical means can further expand its uses. Here, liquid-exfoliated graphene is functionalized with p-aminophenyl moiety using p-nitrophenyl diazonium salts which were diazotized in situ then reduced by tin(II) chloride. The aminophenyl-graphene thus produced is further modified to form polyaniline-graphene (PANI-GNH) by in situ oxidative graft polymerization of aniline using ammonium peroxydisulfate as oxidizing agent. The properties of the PANI-GNH were compared with polyaniline/graphene blends by Raman, infrared and UV-Visible spectroscopy, and cyclic voltammetry. Indeed, PANI-GNH registered different spectrochemical and electrochemical properties compared with the physically blended PANI and GNH, a manifestation of the effect of chemical grafting on the overall property of the modified graphene.

In Situ Synthesis and Nonvolatile Rewritable‐Memory Effect of Polyaniline‐Functionalized Graphene Oxide

A new polyaniline (PANI)-functionalized graphene oxide (GO-PANI) was prepared by using an in situ oxidative graft polymerization of aniline on the surface of GO. Its highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), ionization potential (IP), and electron affinity (EA) values experimentally estimated by the onset of the redox potentials were -5.33, -3.57, 5.59, and 3.83 eV, respectively. A bistable electrical-switching effect was observed in electronic device with the GO-PANI film sandwiched between the indium tin oxide (ITO) and Al electrodes. This device exhibited two accessible conductivity states, that is, the low-conductivity (OFF) state and the high-conductivity (ON) state, and can be switched to the ON state under a negative electrical sweep, and can also be reset to the initial OFF state by a reverse (positive) electrical sweep. The ON state is nonvolatile and can withstand a constant voltage stress of -1 V for 3 h and 10(8) read cycles at -1 V under ambient conditions. The nonvolatile nature of the ON state and the ability to write, read, and erase the electrical states, fulfill the functionality of a rewritable memory. An ON/OFF current ratio of more than 10(4) at -1 V achieved in this memory device is high enough to promise a low misreading rate through the precise control of the ON and OFF states. The mechanism associated with the memory effects was elucidated from molecular simulation results.

Poly(4-vinylaniline)-Polyaniline Bilayer-Modified Stainless Steels for the Mitigation of Biocorrosion by Sulfate-Reducing Bacteria (SRB) in Seawater

A novel strategy by combination of surface-initiated atom transfer radical polymerization (ATRP) and in situ chemical oxidative graft polymerization was employed to tether stainless steel (SS) with poly(4-vinylaniline)-polyaniline (PVAn-PANI) bilayer coatings for mitigating biocorrosion by sulfate-reducing bacteria (SRB) in seawater. A trichlorosilane coupling agent was first immobilized on the SS surfaces to provide sulfonyl halide groups for surface-initiated ATRP of 4-VAn. A subsequent grafting of PANI onto the PVAn-grafted surface was accomplished by in situ chemical oxidative graft polymerization of aniline. The PVAn-PANI bilayer coatings were finally quaternized by hexylbromide to generate biocidal functionality. The so-synthesized SS surface was found to significantly reduce bacterial adhesion and biofilm formation. Electrochemical results revealed that the PVAn-PANI modified SS surface exhibited high resistance to biocorrosion by SRB. With the inherent anticorrosion capability and antibacterial pr...

Surface graft polymerization of conducting polyaniline on waterborne poyurethane‐urea film and its phenol sensing

AbstractWaterborne polyurethane‐ureas (pristine WBPUs: WBPU‐19 and WBPU‐24, fixed soft segment content: 60 wt %) containing dimethylol propionic acid (DMPA)/ethylene diamine (EDA) contents (19/16.8 and 24/11.4 mol %) were prepared. The polyaniline (PANI)‐graft‐WBPU (PANI‐graft‐WBPU) films were prepared by oxidative graft polymerization of aniline on the surface layer of WBPU films. This study focused on the effects of reaction conditions (concentrations/treating times/temperatures of aniline and APS) and DMPA content on the %grafting, conductivity, and mechanical properties of PANI‐graft‐WBPU films. To obtain the maximum %grafting (PANI‐graft‐WBPU‐19: 6.2, and PANI‐graft‐WBPU‐24: 7.4) and conductivity (PANI‐graft‐WBPU‐19: 3.6 × 10−2S/cm, and PANI‐graft‐WBPU‐24: 4.7 × 10−2S/cm), the optimum concentrations/treating times/temperatures of aniline and APS, were found to be 0.35M/10 min/25°C and 0.2M/10 min/0°C, respectively. The tensile strength of film samples was found to be increased in the order of PANI‐graft‐WBPU‐19>pristine WBPU‐19>PANI‐graft‐WBPU‐24>pristine WBPU‐24. The PANI‐graft‐WBPU‐19 (%grafting: 6.2) films on exposure to 0–10,000 ppm phenol solutions showed a well‐defined response behavior, demonstrating high promise for application in aqueous phenol sensors. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Glucose Biosensor from Covalent Immobilization of Chitosan-Coupled Carbon Nanotubes on Polyaniline-Modified Gold Electrode

An amperometric glucose biosensor was prepared using polyaniline (PANI) and chitosan-coupled carbon nanotubes (CS-CNTs) as the signal amplifiers and glucose oxidase (GOD) as the glucose detector on a gold electrode (the Au-g-PANI-c-(CS-CNTs)-GOD biosensor). The PANI layer was prepared via oxidative graft polymerization of aniline from the gold electrode surface premodified by self-assembled monolayer of 4-aminothiophenol. CS-CNTs were covalently coupled to the PANI-modified gold substrate using glutaradehyde as a bifunctional linker. GOD was then covalently bonded to the pendant hydroxyl groups of chitosan using 1,4-carbonyldiimidazole as the bifunctional linker. The surface functionalization processes were ascertained by X-ray photoelectron spectroscopy (XPS) analyses. The field emission scanning electron microscopy (FESEM) images of the Au-g-PANI-c-(CS-CNTs) electrode revealed the formation of a three-dimensional surface network structure. The electrode could thus provide a more spatially biocompatible microenvironment to enhance the amount and biocatalytic activity of the immobilized enzyme and to better mediate the electron transfer. The resulting Au-g-PANI-c-(CS-CNTs)-GOD biosensor exhibited a linear response to glucose in the concentration range of 1-20 mM, good sensitivity (21 μA/(mM·cm(2))), good reproducibility, and retention of >80% of the initial response current after 2 months of storage.

Conducting polymer functionalized multi-walled carbon nanotubes with noble metal nanoparticles: Synthesis, morphological characteristics and electrical properties

We report the synthesis of conducting polyaniline-functionalized multi-walled carbon nanotubes (MWCNTs- f-PANI) containing noble metal (Au and Ag) nanoparticles composites (MWCNTs- f-PANI-Au or Ag-NC). MWCNTs- f-PANI was initially synthesized by functionalizing acyl chloride terminated carbon nanotubes (MWCNTs-COCl) with 2,5-diaminobenzenesulphonic acid (DABSA) via amide bond formation, followed by surface initiated in situ chemical oxidative graft polymerization of aniline in the presence of the ammonium persulphate (APS) as an oxidizing agent. MWCNTs- f-PANI was then dispersed into an aqueous Au or Ag metal salt solution followed by the addition of sodium citrate, which acted as a reducing agent. The resulting composite contained a high level of well dispersed Au or Ag nanoparticles (MWCNTs- f-PANI/Au-NC or MWCNTs- f-PANI-Ag-NC). Morphological and structural characteristics, as well as electrical conducting properties of the hybrid nanocomposites were characterized using various techniques including high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–visible spectroscopy (UV–vis) and four-probe measurements. FT-IR spectra confirmed that PANI was covalently bonded to MWCNTs. TEM images revealed the presence of Au or Ag nanoparticles finely dispersed in the composites with a size of <15 nm. XRD analysis revealed the presence of strong interactions between the metal nanoparticles and MWCNTs- f-PANI, where the metal particles were present in a phase-pure crystalline state with face centered cubic (fcc) structure. The room temperature electrical conductivity of the MWNCTs- f-PANI/Au or Ag composites was 4.8–5.0 S/cm, respectively, which was much higher than that of CNTs- f-PANI (0.18 S/cm) or pure PANI (2.5 × 10 −3 S/cm). A plausible mechanism for the formation of nanocomposites is presented. We expect that the new synthesis strategy reported here will be applicable for the synthesis of other hybrid CNTs–polymer/metal nanocomposites with diverse functionalities. This new type of hybrid nanocomposite material may have numerous applications in nanotechnology, gas sensing, and catalysis.

Oxidative graft polymerization of aniline on the modified surface of polypropylene films

AbstractA novel method for preparing electrically conductive polypropylene‐graft‐polyacrylic acid/polyaniline (PP‐g‐PAA/PANI) composite films was developed. 1,4‐Phenylenediamine (PDA) was introduced on the surface of PP‐g‐PAA film, and then, chemical oxidative polymerization of aniline on PP‐g‐PAA/PDA film was carried out to prepare PP‐g‐PAA/PANI electrically conductive composite films. After each step of reaction, the PP film surface was characterized by attenuated total reflectance Fourier transform infrared spectroscopy. Static water contact angles of the PP, PP‐g‐PAA, and PP‐g‐PAA/PANI films were measured, and the results revealed that graft reactions took place as expected. The morphology of the PP‐g‐PAA film and the PP‐g‐PAA/PANI composite film were observed by atomic force microscopy. The conductivity and the thickness of the PP‐g‐PAA/PANI composite films with 1.5 wt % PANI were around 0.21 S/cm and 0.4 μm, respectively. The PANI on the PP‐g‐PAA/PANI film was reactivated and chain growing occurred to further improve the molecular weight of PANI. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2442–2450, 2007

Oxidative graft polymerization of aniline on the surface of poly(propylene)-graft-polyacrylic acid films

A method for the preparation of electrically conductive poly(propylene) -graft-polyacrylic acid/polyaniline (PP-g-PAA/PANI) composite films was developed. The synthesis was mainly performed by two steps, i.e., the surface graft copolymerization of PP films with acrylic acid induced by ultraviolet (UV) and then chemical oxidative polymerization of aniline. The influence of experimental conditions on graft percentage of PANI on PP-g-PAA films was systematically investigated. It was found that when the polymerization on the surface of PP-g-PAA films was performed in aqueous HCl medium, the optimum aniline concentration was 0.1 M at pH 1. Additionally, UV–visible spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy were used to characterize and analyze the interaction between PAA and aniline, the formation mechanism and the surface structure of the PP-g-PAA/PANI films. The morphologies of the PP-g-PAA/PANI composite films were also detected by scanning electron microscope. The conductivity and the thickness of the composite films with 2 wt.% PANI were about 10 −2S/cm and 0.6 μm, respectively.

Reactive Coupling of 4-Vinylaniline with Hydrogen-Terminated Si(100) Surfaces for Electroless Metal and “Synthetic Metal” Deposition

Pristine and resist-patterned Si(100) substrates were etched by aqueous HF to produce hydrogen-terminated silicon (H-Si(100)) surfaces. The H-Si(100) surface was then subjected to UV-induced reactive coupling of 4-vinylaniline (VAn) to produce the VAn monolayer-modified silicon (VAn-Si) surface. The VAn-Si surface was first functionalized with a "synthetic metal" by oxidative graft polymerization of aniline with the aniline moieties of the coupled VAn molecules. The composition and topography of the VAn-Si and polyaniline (PAn)-grafted VAn-Si (PAn-VAn-Si) surfaces were characterized by X-ray photoelectron spectroscopy and atomic force microscopy, respectively. The doping-undoping (protonation-deprotonation) and redox-coupling (metal reduction) behavior, as well as the electrical conductivity, of the surface-grafted PAn were found to be similar to those of the aniline homopolymer. The VAn-Si surface was also funtionalized by the electroless plating of copper. Not only did the VAn layer provide chemisorption sites for the palladium catalyst, in the absence of prior sensitization by SnCl2, during the electroless plating process, it also served as an adhesion promotion layer and a low-temperature diffusion barrier for the electrolessly deposited copper. Finally, micropatterning of the grafted PAn and of the electrolessly deposited copper were demonstrated on the resist-patterned VAn-Si surfaces.

Oxidative Graft Polymerization of Aniline on PTFE Films Modified by Surface Hydroxylation and Silanization

Chemical modification of argon plasma-pretreated poly(tetrafluoroethylene) (PTFE) films by UV-induced graft copolymerization with 2-hydroxyethyl methacrylate (HEMA), followed by silanization with (p-aminophenyl)trimethoxysilane (APTS), and finally oxidative graft polymerization of aniline had been carried out to render the PTFE surfaces electrically conductive. The chemical composition of the PTFE surface after each step of surface modification was analyzed by X-ray photoelectron spectroscopy (XPS). The graft concentration of the HEMA polymer and the aniline polymer increased with increasing concentration of the respective monomer used for graft polymerization. The extent of APTS chemisorption increased with the graft concentration of the HEMA polymer, as well as the concentration of the APTS solution. A high extent of APTS chemisorption, in turn, led to a high graft concentration of the aniline polymer and thus a low surface resistance of the resulting PTFE film upon acid treatment (reprotonation) of the grafted aniline polymer. The grafted aniline polymer exhibited similar intrinsic oxidation states and reprotonation−deprotonation behavior as those of the aniline homopolymer. The grafted aniline polymer was found to be more effectively protonated by 10-camphorsulfonic acid (CSA) than by HClO4. The optimum surface resistance of the aniline polymer-grafted PTFE film was on the order of 103 Ω/sq.

Oxidative graft polymerization of aniline on Si(100) surface modified by plasma polymerization of glycidyl methacrylate

AbstractModification of argon plasma‐pretreated Si(100) surfaces via plasma polymerization of glycidyl methacrylate(GMA), followed by reactive coupling of the epoxide groups of the plasma deposited GMA chains with aniline, and finally by oxidative graft polymerization of aniline was carried out. An alternative approach involved the modification of the argon plasma‐pretreated Si(100) surfaces via plasma polymerization of glycidyl methacrylate(GMA), followed by direct oxidative graft polymerization of aniline and thermal curing. The compositions and chemical states of the modified Si surfaces were characterized by X‐ray photoelectron spectroscopy (XPS). The two methods of surface modification of the Si(100) surfaces produced similar results. The protonation‐deprotonation behavior, the interconvertible intrinsic redox states, and the metal reduction behavior (the electroless plating of Pd from the Pd(II) ion solution) of the grafted polyaniline (PANI) chains on the Si(100) surface were grossly similar to those of the PANI homopolymer. The coupling of PANI to the covalently tethered GMA chains on the Si(100) surface was suggested by the cohesive failure inside the epoxy adhesive that was applied to the modified Si surface in an attempt to peel off the PANI layer from the GMA plasma‐polymerized Si (GMA‐pp‐Si) substrate.

Electroless Metallization of Glass Surfaces Functionalized by Silanization and Graft Polymerization of Aniline

Silanization of glass surfaces by (3-glycidoxypropyl)trimethoxysilane (GPS) provided a surface-coupled layer of functional molecules for the subsequent reaction with aniline (An). The so-modified glass surface (the An−GPS−glass surface) was then subjected to oxidative graft polymerization of aniline. The composition and microstructure of the modified glass surfaces were characterized by X-ray photoelectron spectroscopy (XPS), UV−visible absorption spectroscopy, and atomic force microscopy (AFM). The protonation−deprotonation behavior, the interconvertible intrinsic redox states, and the spontaneous metal reduction behavior of the grafted polyaniline (PANI) chains on the glass surface (the PANI−An−GPS−glass surface) were similar to those of the PANI homopolymer. The PANI−An−GPS−glass surface with the electrolessly deposited palladium could be used to catalyze the electroless deposition of copper (the Cu−Pd−PANI−An−GPS−glass surface). The spatial distribution of the grafted PANI chains into the matrix of th...

Oxidative Graft Polymerization of Aniline on Modified Si(100) Surface

Chemical modification of the argon plasma-pretreated Si(100) surface by UV-induced surface graft polymerization with either glycidyl methacrylate (GMA) or glycidyl acrylate (GA) was carried out. The GA graft polymerized Si substrate was further subjected to coupling reaction with aniline (An) and finally oxidative graft polymerization of An. The composition and microstructure of the graft-polymerized Si(100) surfaces were studied by X-ray photoelectron spectroscopy (XPS) and imaging XPS, respectively. The graft concentrations of the GMA polymer, GA polymer, and An polymer increased with increasing concentration of the respective monomer used for graft polymerization. The graft polymerization efficiency of GA on the Ar plasma-pretreated Si(100) was much higher than that of GMA. Ethanol, when used as a solvent, catalyzed the coupling reaction of the epoxide groups of GA with An and should be of more than 40 vol % in concentration to achieve the optimum effect. The protonation−deprotonation characteristics, interconvertible intrinsic redox states, and metal reduction behavior of the polyaniline (PANI) chains, obtained from subsequent oxidative graft polymerization of An on the modified Si(100) surface, were grossly similar to those of the PANI homopolymer. The resistance of the modified Si(100) surface from consecutive graft polymerization with GA and An was on the order of 107 Ω/sq.