scispace - formally typeset
Search or ask a question

Showing papers on "Surface modification published in 2008"


Journal ArticleDOI
TL;DR: This paper presents a meta-analyses of the physical and chemical properties of Boron-Doped Diamond for Electrochemistry as well as a mechanistic analysis of the properties of the diamond itself and some of its applications.
Abstract: 3.6.1. Polishing and Cleaning 2663 3.6.2. Vacuum and Heat Treatments 2664 3.6.3. Carbon Electrode Activation 2665 3.7. Summary and Generalizations 2666 4. Advanced Carbon Electrode Materials 2666 4.1. Microfabricated Carbon Thin Films 2666 4.2. Boron-Doped Diamond for Electrochemistry 2668 4.3. Fibers and Nanotubes 2669 4.4. Carbon Composite Electrodes 2674 5. Carbon Surface Modification 2675 5.1. Diazonium Ion Reduction 2675 5.2. Thermal and Photochemical Modifications 2679 5.3. Amine and Carboxylate Oxidation 2680 5.4. Modification by “Click” Chemistry 2681 6. Synopsis and Outlook 2681 7. Acknowledgments 2682 8. References 2682

2,240 citations


Journal ArticleDOI
TL;DR: The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered and some future trends and prospective in these research areas are also discussed.
Abstract: Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed.

1,827 citations


Journal ArticleDOI
TL;DR: Methods for the preparation of mesoporous carbon materials with extremely high surface areas and ordered mesostructures, with potential applications as catalysts, separation media, and advanced electronic materials in many scientific disciplines are developed.
Abstract: Porous carbon materials are of interest in many applications because of their high surface area and physicochemical properties. Conventional syntheses can only produce randomly porous materials, with little control over the pore-size distributions, let alone mesostructures. Recent breakthroughs in the preparation of other porous materials have resulted in the development of methods for the preparation of mesoporous carbon materials with extremely high surface areas and ordered mesostructures, with potential applications as catalysts, separation media, and advanced electronic materials in many scientific disciplines. Current syntheses can be categorized as either hard-template or soft-template methods. Both are examined in this Review along with procedures for surface functionalization of the carbon materials obtained.

1,716 citations


Journal ArticleDOI
TL;DR: In this paper, surface modification of natural halloysite clay nanotubes with γ-aminopropyltriethoxysilane (APTES) was investigated.
Abstract: Surface modification of natural halloysite clay nanotubes with γ-aminopropyltriethoxysilane (APTES) was investigated. Untreated and modified samples were characterized by nitrogen adsorption, X-ray diffraction, elemental analysis, thermogravimetry, transmission electron microscopy, atomic force microscopy, MAS nuclear magnetic resonance (29Si, 13C, 29Al), and Fourier transform infrared spectroscopy. The modification mechanism was found to include not only the direct grafting of APTES onto the hydroxyl groups of the internal walls, edges and external surfaces of the nanotubes but other processes in which oligomerized APTES condensed with the directly grafted APTES to form a cross-linked structure. The thermal and evacuation pretreatment conditions were found to play an important role in controlling the extent and mechanism of the modification. The extent of modification is also strongly affected by the morphological parameters of the original clay samples. This study demonstrates that the surface chemistry...

813 citations


Journal ArticleDOI
Hong Chen1, Lin Yuan1, Wei Song1, Zhongkui Wu1, Dan Li1 
TL;DR: The principles for designing biocompatibility materials are brought forth, such as passivating the polymer surfaces to minimize non-specific protein interaction, or decorating polymer surfaces with biomolecules to induce specific protein adsorption and cell responses.

642 citations


Journal ArticleDOI
TL;DR: The surface of cellulose nanocrystals, prepared by sulfuric acid hydrolysis of cotton, was rendered cationic through a reaction with epoxypropyltrimethylammonium chloride.
Abstract: The surface of cellulose nanocrystals, prepared by sulfuric acid hydrolysis of cotton, was rendered cationic through a reaction with epoxypropyltrimethylammonium chloride. The resultant nanocrystal suspensions were characterized by ζ-potential, conductometric titration and polarized light microscopy. Atomic force microscopy (AFM) showed no change in the size or shape of the nanocrystals, but the functionalization process reversed the surface charge and led to a reduction of the total surface charge density. These modifications led to stable aqueous suspensions of nanocrystalline cellulose with unexpected gelling and rheological properties. Shear birefringence was observed, but no liquid crystalline chiral nematic phase separation was detected.

521 citations


Journal ArticleDOI
TL;DR: The fiber membranes functionalized with Pt nanoparticles and nanowires are interesting for a number of catalytic applications and showed excellent catalytic activity for the hydrogenation of azo bonds in methyl red.
Abstract: This paper reports a simple procedure for derivatizing the surface of anatase TiO2 nanofibers with Pt nanoparticles and then Pt nanowires. The nanofibers were prepared in the form of a nonwoven mat by electrospinning with a solution containing both poly(vinyl pyrrolidone) and titanium tetraisopropoxide, followed by calcination in air at 510 degrees C. The fiber mat was then immersed in a polyol reduction bath to coat the surface of anatase fibers with Pt nanoparticles of 2-5 nm in size with controllable density of coverage. Furthermore, the coated fibers could serve as a three-dimensional scaffold upon which Pt nanowires of roughly 7 nm in diameter could be grown at a high density and with a length up to 125 nm. The fiber membranes functionalized with Pt nanoparticles and nanowires are interesting for a number of catalytic applications. It was found to show excellent catalytic activity for the hydrogenation of azo bonds in methyl red, which could be operated in a continuous mode by passing the dye solution through the membrane at a flow rate of 0.5 mL/s.

479 citations


Journal ArticleDOI
TL;DR: In this paper, various possibilities are discussed how nanoparticles can be protected by organic ligands and how these ligands can be used to introduce functionalities, such as grafting of an already functionalized ligand on the nanoparticle surface, exchanging part or all existing ligands on the particle surface, or grafting a ligand in a nanoparticle followed by modification by organic chemical reactions.
Abstract: Metal or metal oxide nanoparticles possess unique features compared to equivalent larger-scale materials. For applications, it is often necessary to stabilize or functionalize such nanoparticles. Thus, modification of the surface of nanoparticles is an important chemical challenge. In this survey, various possibilities are discussed how nanoparticles can be protected by organic ligands and how these ligands can be used to introduce functionalities. The preparative possibilities include grafting of an already functionalized ligand on the nanoparticle surface, exchanging part or all existing ligands on the nanoparticle surface, or grafting of a ligand on a nanoparticle followed by modification by organic chemical reactions.

466 citations


Journal ArticleDOI
03 Mar 2008-Polymer
TL;DR: In this paper, microfibrillated cellulose (MFC) possessing a "web-like" morphology was successfully modified with three different coupling agents: 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxyselane, and a titanate coupling agent (Lica 38), which changed the surface character of MFC from hydrophilic to hydrophobic.

456 citations


Journal ArticleDOI
TL;DR: A zwitterionic poly(carboxybetaine acrylamide) (polyCBAA) biomimetic material was employed to create a unique biorecognition coating with an ultralow fouling background, enabling the sensitive and specific detection of proteins in blood plasma.
Abstract: A crucial step in the development of implanted medical devices, in vivo diagnostics, and microarrays is the effective prevention of nonspecific protein adsorption from real-world complex media such as blood plasma or serum. In this work, a zwitterionic poly(carboxybetaine acrylamide) (polyCBAA) biomimetic material was employed to create a unique biorecognition coating with an ultralow fouling background, enabling the sensitive and specific detection of proteins in blood plasma. Conditions for surface activation, protein immobilization, and surface deactivation of the carboxylate groups in the polyCBAA coating were determined. An antibody-functionalized polyCBAA surface platform was used to detect a target protein in blood plasma using a sensitive surface plasmon resonance (SPR) sensor. A selective protein was directly detected from 100% human blood plasma with extraordinary specificity and sensitivity. The total nonspecific protein adsorption on the functionalized polyCBAA surface was very low (<3 ng/cm2 ...

396 citations


Journal ArticleDOI
TL;DR: The adhesive proteins secreted by mussels are the inspiration behind a versatile approach to the surface modification of a wide range of inorganic and organic materials, resulting in the fabrication of multifunctional coatings for a variety of applications.
Abstract: The adhesive proteins secreted by mussels are the inspiration behind a versatile approach to the surface modification of a wide range of inorganic and organic materials, resulting in the fabrication of multifunctional coatings for a variety of applications.

Journal ArticleDOI
TL;DR: In this paper, the effect of different functionalization methodologies on dispersion of CNTs in aqueous media was evaluated, and the authors concluded that all methodologies used showed a percentage of adsorption of functional groups on the CNT.

Posted Content
TL;DR: It is shown that, as a rule, 100% coverage of graphene by complex functional groups (in contrast with hydrogen and fluorine) is unreachable.
Abstract: Experimental and theoretical results on chemical functionalization of graphene are reviewed. Using hydrogenated graphene as a model system, general principles of the chemical functionalization are formulated and discussed. It is shown that, as a rule, 100% coverage of graphene by complex functional groups (in contrast with hydrogen and fluorine) is unreachable. A possible destruction of graphene nanoribbons by fluorine is considered. The functionalization of infinite graphene and graphene nanoribbons by oxygen and by hydrofluoric acid is simulated step by step.

Journal ArticleDOI
TL;DR: The combination of both organic and inorganic constituents is expected to result into truly bone-resembling coatings, and as such to a new generation of surface-modified titanium implants with improved functionality and biological efficacy.
Abstract: This paper reviews current physicochemical and biochemical coating techniques that are investigated to enhance bone regeneration at the interface of titanium implant materials. By applying coatings onto titanium surfaces that mimic the organic and inorganic components of living bone tissue, a physiological transition between the non-physiological titanium surface and surrounding bone tissue can be established. In this way, the coated titanium implants stimulate bone formation from the implant surface, thereby enhancing early and strong fixation of bone-substituting implants. As such, a continuous transition from bone tissue to implant surface is induced. This review presents an overview of various techniques that can be used to this end, and that are inspired by either inorganic (calcium phosphate) or organic (extracellular matrix components, growth factors, enzymes, etc.) components of natural bone tissue. The combination, however, of both organic and inorganic constituents is expected to result into truly bone-resembling coatings, and as such to a new generation of surface-modified titanium implants with improved functionality and biological efficacy.

Journal ArticleDOI
TL;DR: Dynamic surface rearrangement and thermal stability of N-functional groups on carbon nanotubes, obtained by functionalization of pristine CNTs with NH(3), were studied by temperature-programmed XPS and MS and a conversion into graphitic nitrogen was observed.

Journal ArticleDOI
TL;DR: In this paper, surface modification of electrospun polyurethane (PU) fibrous membranes, using a process which involved plasma pretreatment, UV-induced graft copolymerization of 4-vinylpyridine (4VP), and quaternization of the grafted pyridine groups with hexylbromide.

Journal ArticleDOI
TL;DR: The utilization of N,N'-disubstituted ureas and thioureas as design elements in the synthesis of crystalline organic solids is reviewed.

Journal ArticleDOI
TL;DR: Sorption data are consistent with the idea that incorporated surface oxides create polar regions that reduce the surface area available for naphthalene sorption, and highlight the important role of surface chemistry in controlling the environmental properties of CNTs.
Abstract: As greater quantities of carbon nanotubes (CNTs) enter the environment, they will have an increasingly important effect on the availability and transport of aqueous contaminants. As a consequence of purification, deliberate surface functionalization, and/or exposure to oxidizing agents after release to the environment, CNTs often contain surface oxides (i.e., oxygen containing functional groups). To probe the influence that surface oxides exert on CNT sorption properties, multiwalled CNTs (MWCNTs) with varying oxygen concentrations were studied with respect to their sorption properties toward naphthalene. For pristine (as-received) MWCNTs, the sorption capacity was intermediate between that of a natural char and a granular activated carbon. Sorption data also reveal that a linear relationship exists between the oxygen content of MWCNTs and their maximum adsorption capacity for naphthalene, with 10% surface oxygen concentration resulting in a roughly 70% decrease in maximum adsorption capacity. The relative distribution of sorption energies, as characterized by Freundlich isotherm exponents was, however, unaffected by oxidation. Thus, the data are consistent with the idea that incorporated surface oxides create polar regions that reduce the surface area available for naphthalene sorption. These results highlight the important role of surface chemistry in controlling the environmental properties of CNTs.

Journal ArticleDOI
TL;DR: In this paper, surface modifications have been made to the activated carbon material, including alkaline treatment and loading of titanium dioxide nanoparticles, and the modified electrode material demonstrated enhanced electrosorption capacity and reduced physical sorption at the pores, so desorption is more efficiently.

Journal ArticleDOI
07 Mar 2008-ACS Nano
TL;DR: The ease of surface functionalization and incorporation of a variety of biotargeting molecules, combined with their observed noncytotoxicity makes these fluorescent ORMOSIL nanoparticles potential candidates as efficient probes for optical bioimaging, both in vitro and in vivo.
Abstract: In this paper we report the synthesis and characterization of organically modified silica (ORMOSIL) nanoparticles, covalently incorporating the fluorophore rhodamine-B, and surface-functionalized with a variety of active groups. The synthesized nanoparticles are of ultralow size (diameter ∼20 nm), highly monodispersed, stable in aqueous suspension, and retain the optical properties of the incorporated fluorophore. The surface of the nanoparticles can be functionalized with a variety of active groups such as hydroxyl, thiol, amine, and carboxyl. The carboxyl groups on the surface were used to conjugate with various bioactive molecules such as transferrin, as well as monoclonal antibodies such as anti-claudin 4 and anti-mesothelin, for targeted delivery to pancreatic cancer cell lines. In vitro experiments have revealed that the cellular uptake of these bioconjugated (targeted) nanoparticles is significantly higher than that of the nonconjugated ones. The ease of surface functionalization and incorporation ...

Journal ArticleDOI
TL;DR: In this paper, the photocatalytic activity of as-modified TiO2 under UV irradiation was investigated and it was found that the effect of phosphate modification is attributed to the surface-bound phosphate anion.
Abstract: Phosphate modified TiO2 photocatalysts were prepared by phosphoric acid treatment before or after TiO2 crystallization. Substrates with different structures were chosen to explore the photocatalytic activity of as-modified TiO2 under UV irradiation. It was found that the effect of phosphate modification is definitely attributed to the surface-bound phosphate anion, and the modification by phosphate can affect both the rates and pathways of photocatalytic reactions, which are of great dependence on the structures and properties of substrates. The degradation of substrates (such as 4-chloropehenol, phenol, and rhodamine B) with weak adsorption on the pure TiO2 was markedly accelerated by phosphate modification, while substrates (such as dichloroacetic acid, alizarin red, and catechol) with strong adsorption exhibited a much lower degradation rate in the phosphate modified system. A much higher amount of hydroxyl radical was produced in phosphate modified system. All of the experimental results imply that ph...

Journal ArticleDOI
TL;DR: In this paper, the surface modification of polyethyleneterephthalate (PET) polymer by plasma treatment was studied and the changes in surface morphology were observed by using atomic force microscopy (AFM).
Abstract: In this paper, we present a study on the surface modification of polyethyleneterephthalate (PET) polymer by plasma treatment. The samples were treated by nitrogen and oxygen plasma for different time periods between 3 and 90 s. The plasma was created by a radio frequency (RF) generator. The gas pressure was fixed at 75 Pa and the discharge power was set to 200 W. The samples were treated in the glow region, where the electrons temperature was about 4 eV, the positive ions density was about 2 × 1015 m−3, and the neutral atom density was about 4 × 1021 m−3 for oxygen and 1 × 1021 m−3 for nitrogen. The changes in surface morphology were observed by using atomic force microscopy (AFM). Surface wettability was determined by water contact angle measurements while the chemical composition of the surface was analyzed using XPS. The stability of functional groups on the polymer surface treated with plasma was monitored by XPS and wettability measurements in different time intervals. The oxygen-plasma-treated samples showed much more pronounced changes in the surface topography compared to those treated by nitrogen plasma. The contact angle of a water drop decreased from 75° for the untreated sample to 20° for oxygen and 25° for nitrogen-plasma-treated samples for 3 s. It kept decreasing with treatment time for both plasmas and reached about 10° for nitrogen plasma after 1 min of plasma treatment. For oxygen plasma, however, the contact angle kept decreasing even after a minute of plasma treatment and eventually fell below a few degrees. We found that the water contact angle increased linearly with the O/C ratio or N/C ratio in the case of oxygen or nitrogen plasma, respectively. Ageing effects of the plasma-treated surface were more pronounced in the first 3 days; however, the surface hydrophilicity was rather stable later. Copyright © 2008 John Wiley & Sons, Ltd.

Journal ArticleDOI
01 Feb 2008-Carbon
TL;DR: In this article, a well-dispersed epoxy/single-walled carbon nanotube (epoxy/SWCNT) composites were prepared by oxidization and functionalization of the SWCNT surfaces using polyamidoamine generation-0 (PAMAM-0) dendrimer.

Journal ArticleDOI
TL;DR: In this paper, a polypropylene (PP) film is plasma-treated using a dielec barrier discharge (DBD) operating in air at medium pressure (5.0 kPa).
Abstract: Plasma treatment is often used to modify the surface properties of polymer films, since it offers numerous advantages over the conventional surface modification techniques. In this paper, a polypropylene (PP) film is plasma-treated using a dielec. barrier discharge (DBD) operating in air at medium pressure (5.0 kPa). The modified polymer films are characterized using contact angle measurements, XPS-anal. and attenuated total reflectance-Fourier transform IR (ATR-FTIR) spectroscopy. Results show that plasma treatment leads to a remarkable decrease in contact angle owing to the implantation of oxygen-contg. functional groups. Using XPS and ATR-FTIR, these oxygen-contg. groups can be identified as C-O, C=O and O-C=O. In this paper, it is also shown that XPS is well-suited to provide quant. chem. anal. of the PP films, while ATR-FTIR can only give qual. information. To perform quant. ATR-FTIR measurements, chem. derivatization will be explored in the near future

Journal ArticleDOI
TL;DR: N-Propylsalicylaldimino-functionalized SBA-15 mesoporous silica was prepared, characterized and used as an adsorbent for heavy metal ions and showed high adsorption capacity and high selectivity for copper ions.

Journal ArticleDOI
TL;DR: Li et al. as mentioned in this paper showed that surface modification with AlPO 4 (<4 wt %) increases the discharge capacity and drastically reduces the irreversible capacity loss in the first cycle compared to the values observed with the pristine (unmodified) sample.
Abstract: Layered Li[Li 0.2 Mn 0.54 Co 0.13 Ni 0.13 ]O 2 cathode, which is a solid solution between layered Li[Li 1/3 Mn 2/3 ]O 2 and Li[Ni 1/3 Mn 1/3 Co 1/3 ]O 2 , has been surface modified with various amounts (0-4 wt %) of AlPO 4 and characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical measurements in lithium cells. Annealing the surface-modified samples at 400 and 700°C leads to the formation of Li 3 PO 4 on the surface and an incorporation of some Al 3+ into the layered oxide lattice. More importantly, surface modification with AlPO 4 (<4 wt %) increases the discharge capacity and drastically reduces the irreversible capacity loss in the first cycle compared to the values observed with the pristine (unmodified) sample. For example, the irreversible capacity loss decreases from 75 to 27 mAh/g and the discharge capacity increases from 253 to 279 mAh/g on surface modification with 2 wt % AlPO 4 . The results are explained based on the retention of more oxide ion vacancies in the layered lattice after surface modification.

Journal ArticleDOI
29 Aug 2008-Sensors
TL;DR: This review will illustrate how mesoporous silicas have been applied to sensing changes in relative humidity, changes in pH, metal cations, toxic industrial compounds, volatile organic compounds, small molecules and ions, nitroenergetic compounds, and biologically relevant molecules.
Abstract: Mesoporous silicas, especially those exhibiting ordered pore systems and uniform pore diameters, have shown great potential for sensing applications in recent years. Morphological control grants them versatility in the method of deployment whether as bulk powders, monoliths, thin films, or embedded in coatings. High surface areas and pore sizes greater than 2 nm make them effective as adsorbent coatings for humidity sensors. The pore networks also provide the potential for immobilization of enzymes within the materials. Functionalization of materials by silane grafting or through cocondensation of silicate precursors can be used to provide mesoporous materials with a variety of fluorescent probes as well as surface properties that aid in selective detection of specific analytes. This review will illustrate how mesoporous silicas have been applied to sensing changes in relative humidity, changes in pH, metal cations, toxic industrial compounds, volatile organic compounds, small molecules and ions, nitroenergetic compounds, and biologically relevant molecules.

Journal ArticleDOI
TL;DR: This paper describes the process of modifying large quantities of natural fibers with bacterial cellulose through their use as substrates for bacteria during fermentation, which enhances their adhesion to renewable polymers.

Journal ArticleDOI
TL;DR: In this article, the structure and morphology of the coated Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 samples were characterized and compared.

Journal ArticleDOI
TL;DR: This work demonstrates a convenient and efficient method for using zwitterionic polymers with a catechol anchor group to achieve ultra low fouling surfaces via surface modification, for applications in complex media.