Organic Surface Modification Research Articles

Surface organic modification of titanium dioxide fine particles through photo polymerization

AbstractCC unsaturated groups were chemically inserted onto TiO2 particles surfaces through chemical reaction of hydroxyl group on the TiO2 fine particle surface with 2,4‐diidocyanatotoluene (TDI) first, and then with 2‐hydroxyethyl acrylate (HEA). Finally, TiO2 fine particles with surface organic modification were made through the free radical copolymerization reaction with n‐butyl acrylate (BA) monomer under UV irradiation. The structure and properties of unmodified and modified TiO2 were studied by FT‐IR, XPS, TGA, TEM, lipophilic rates, and adhesion properties tests. The results show that the surface of TiO2 has been successfully introduced with the organic chains through chemical bonding linkage; the surface lipophilic rates of TiO2 particles are increased. The dispersion and compatibility of the modified TiO2 particles in a commercial ink 508C resin greatly improve as compared with that of unmodified TiO2, and agglomeration of particles obviously reduces. The adhesion strength between the white printing ink made from the modified TiO2 particles and BOPP is much better than that from the unmodified TiO2. When the organic rate reached 24.93%, the adhesion strength reaches Grade I. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Surface Organic Modification of In<SUB>2</SUB>O<SUB>3</SUB> Nanoparticle Assemblies and Their Flammable Gas Sensing Properties

Surface Organic Modification of In<SUB>2</SUB>O<SUB>3</SUB> Nanoparticle Assemblies and Their Flammable Gas Sensing Properties

Surface Modification of Sepiolite in Aqueous Gels by Using Methoxysilanes and Its Impact on the Nanofiber Dispersion Ability

Surface modification reactions on needle-like sepiolite using alkyl and functional silanes have been carried out in the form of aqueous gels. In contrast with modifications in organic solvents, reactions in water make it possible to modify the surface of almost-individual sepiolite fibers and produce either a continuous coating or a nanotexturization of the sepiolite fiber surface, depending on the reaction conditions. This clean procedure substitutes advantageously organic solvent surface modifications and allows the tuning of surface properties such as specific surface area, wetting behavior, and chemical functionalization. A consequence of such tuning is, for example, the excellent dispersion of modified sepiolite nanofibers in a great variety of polymers by routine compounding and processing techniques.

Preparation and properties of polyurethane/zeolite 13X composites

The pre-polymerization method was used to prepare polyurethane/zeolite 13X (PU/13X) composites. The effects of zeolite 13X content and its surface organic modification on the mechanical properties of composites were investigated. It was demonstrated that the mechanical properties of PU/13X composites were better than that of pure PU. The surface organic modification of zeolite 13X had no obvious effect on the mechanical properties of PU/13X composites. The optimal tensile strength and tear strength were obtained with 3–5% and 5–7% zeolite 13X loading, respectively. Thermogravimetric analysis (TGA) results showed that the decomposition temperature of PU/13X composites increased in comparison with pure PU. Dynamic mechanical analyzer (DMA) suggested a lower glass transition temperature ( T g ) and better micro-phase separation of soft and hard segments in PU/13X composites. Besides, PU/13X composites had excellent solvent resistance performance.

Silylated Co3O4-m-SiO2 catalysts for Fischer–Tropsch synthesis

Silylated Co3O4-mesoporous SiO2 catalysts were prepared by a surface organic modification to understand the influence of a hydrophobic surface on their performance in the Fischer–Tropsch synthesis (FTS). Fourier transform infra-red (FT-IR) spectra showed that the reaction of the surface silanol groups with hexamethyldisilazane (HMDS) took place effectively, and X-ray diffraction (XRD) indicated that such a modification did not affect Co3O4 crystallite size. Furthermore, hydrogen temperature programmed reduction (H2-TPR) illustrated a higher extent of reduction for silylated Co3O4-m-SiO2 catalysts. As a result, such a silylated core–shell structured Co catalyst showed the higher catalytic activity and better selectivity towards C5–C18 fraction than the unsilylated Co3O4-m-SiO2 catalyst in the FTS, which was likely favorable to the internal transportation and their hydrophobic shell.

Preparation and Characterization of Polypyrrole/Attapulgite with Organic Surface Modification Conducting Composite

Attapulgite was organic surface modified with silane coupling agent (KH570) and acetone, with ferric chloride (FeCl3∙6H2O) as the oxidant, sulfamic acid(SA) as dopant, prepared polypyrrole/attapulgite with organic surface modification conducting nano-composite materials (PPy/ATTP-KH) by chemical oxidation polymerization, and using IR, XRD and SEM characterization methods to characterize Internal structure of composite materials obtained. The results show that in the condition of n(Py):n(FeCl3∙6H2O):n(SA) =1:1:0.5, and with the increase of contents, composite conductivity increased and then decreased, when the contents of attapulgite is to 50%, the conductivity reaches maximum 30.0 S•cm-1. We can see from the IR spectrum, silane coupling agent and hydroxyl of attapulgite surfaces have a chemical bonding, and plays a good modification to the surfaces of attapulgite, Thereby enhancing the conductivity of the composite materials.

Strategies for controlling biofouling in membrane filtration systems: challenges and opportunities

Biofouling is a critical problem in many membrane filtration processes. This review highlights the emerging strategies for polymer membrane modifications using organic and inorganic additives and surface modification to mitigate foulant deposition and biofilm formation. Constraints and opportunities for future implementation in membrane systems are outlined from the perspectives of water and wastewater treatment applications.

Surface modification of hafnia with polyelectrolytes based on the spin-coating electrostatic self-assembly method

In this paper, we describe organic surface modification and functionalization of a hafnia substrate, which has been extensively investigated as a replacement of the gate insulting SiO 2 layer in field effect transistors. The surface state of the hafnia was assessed by water contact angle ( θ water) measurement with comparison to that of the silicone during the layer-by-layer (LBL) deposition of poly(allyamine hydrochloride) (PAH)/poly(styrene sulfonate) (PSS) bilayers by means of the spin-coating electrostatic self-assembly, SCESA, method. The surface state of virgin hafnia ( θ water = 73 ± 1°) turned hydrophilic ( θ water = 8 ± 2°) after submission to the standard RCA cleaning process of silicon. The thickness of the multilayer films on the cleaned hafnia surface was found to grow linearly with an increase in the number of PAH/PSS bilayers ( d = 2.2 ± 0.1 nm), indicating the consistency in the formation of uniform films. The average water contact angle of the PAH and PSS layers on hafnia alternately switched between 36.0 ± 0.7° and 29.7 ± 0.4° during the nine deposition cycles. The analysis of the surface topography by means of atomic force microscopy (AFM) indicated that the surface roughness of the first PAH layer deposited on the hafnia was strongly smoothed from 1.54 to 0.44 nm with increasing the LBL deposition of polyelectrolytes.

Ｆｌａｓｈ Ｃｒｅａｔｉｏｎ法により合成した酸化物および複合ナノ粒子の微構造と界面特性

Dispersion behavior of nanoparticles in organic solvent depends on surface molecular structure, even if the material and size of particles are same. In order to discuss the effect of surface conditions of nanoparticles on dispersion behavior in organic solvent and surface modification behavior, single phase SiO2 and TiO2 nanoparticles and SiO2-TiO2 composite particles were prepared by using flash creation method (FC method) with different thermal source, DC plasma or burner. By the observation of TiO2-SiO2 composite particles by TEM-EDS system, the microstructure of composite particles was estimated that SiO2 layer coated on core TiO2 nanoparticles. Surface OH group structure, dispersion behavior in N-methyl-2-pyrrolidone (NMP) of each TiO2 nanoparticles was depended on the thermal source of FC method. When thermal source used was burner, the high OH group density and well dispersion behavior was observed. However, after surface modification by silane coupling agent, the aggregate size of TiO2 nanoparticles prepared by DC plasma in NMP was decreased.

Surface organic modification of Fe3O4 magnetic nanoparticles

The surface organic modification of Fe3O4 nanoparticles with silane coupling reagent KH570 was studied. The modified and unmodified nanoparticles were characterized by FT-IR, XPS and TEM. The spectra of FT-IR and XPS revealed that KH570 was coated onto the surface of Fe3O4 nanoparticles to get Fe-OSi bond and an organic coating layer also was formed. Fe3O4 nanoparticles were spheres partly with mean size of 18.8 nm studied by TEM, which was consistent with the result 17.9 nm calculated by Scherrer’s equation. KH570 was adsorbed on surface and formed chemistry bond to be steric hindrance repulsion which prevented nanoparticles from reuniting. Then glycol-based Fe3O4 magnetic liquids dispersed stably was gained.

CH 3-modified Co/Ru/SiO 2 catalysts and the performances for Fischer–Tropsch synthesis

CH 3-modified Co/Ru/SiO 2 catalysts were prepared and the catalytic performances for Fischer–Tropsch synthesis were investigated. The modified and unmodified catalysts were characterized by FT-IR, N 2 physisorption, TG, XRD, TPR and DRIFTS. FT-IR indicated an effective surface organic modification. TG suggested that modified catalysts had good thermal stability. XRD and TPR showed that modified catalysts had similar reducibility and Co 3O 4 particle size with unmodified catalyst. During reaction tests in a fixed bed reactor it was found that compared with unmodified Co/Ru/SiO 2 catalyst CH 3-modified Co/Ru/SiO 2 catalysts showed higher selectivity to C 5–C 11 hydrocarbons, which should be ascribed to hydrophobic surface of CH 3-modified Co/Ru/SiO 2 catalysts.

Synthesis of visible light-activated TiO 2 photocatalyst via surface organic modification

A visible light-activated TiO 2 photocatalyst was successfully synthesized by the surface organic modification to sol–gel–hydrothermal synthesized TiO 2. The surface hydroxyls of TiO 2 nanoparticles reacted with the active –NCO groups of tolylene diisocyanate (TDI) to form a surface complex that was confirmed by the FT–IR and XPS spectra. Due to the existence of surface complex, the absorption edge of as-prepared TDI-modified TiO 2 nanomaterial extended well into visible region. Compared with unmodified TiO 2 and Degussa P25, the TDI-modified TiO 2 photocatalysts showed higher activity for the photocatalytic degradation of methylene blue under visible light irradiation.

Structural Characterization and Thermal Decomposition Behavior of Microsized and Nanosized CaCO<SUB>3</SUB>

The surface organic modification of nanosized CaCO_3 with palmitic acid was carried out. The prepared samples were characterized by SEM, TEM, XRD, FTIR, and TG-DTG techniques. A comparative study on the crystal structure and thermal decomposition characteristics of nanosized CaCO_3, modified nanosized CaCO_3, and microsized CaCO_3 was made. According to the spectra of FTIR, it was inferred that the chemical binding and the physical adsorption between palmitic acid and nanosized CaCO_3 have happened during the modification reaction. The results also revealed that the infrared absorption peaks of C-O bond of modified and unmodified nanosized CaCO_3 shifted to a higher frequency by 35 cm~(-1) compared with that of microsized CaCO_3. The mechanism of blue shift in nanosized CaCO_3 was discussed, and it was believed that crystalline electric field effect and size effect influenced their infrared spectra. TG-DTG analysis showed that nanosized CaCO_3, modified nanosized CaCO_3, and microsized CaCO_3 decomposed at 735.0, 764.7, and 775.6 ℃, respectively. The decrease of the decomposition temperature was supposed to be related to the lattice expansion and crystallographic deformation of nanosized CaCO_3.

Use of Sonication and Influence of Clay Type on the Enhancement in Physical Properties of Poly(methyl methacrylate) Nanocomposites

ABSTRACTThe nature of the dispersion of a clay platelet in a resin composite will play an important role in the process of enhancement of the physical properties of that material. This paper describes studies of ultrasonically and mechanically mixed dispersion of various clays in methyl methacrylate (MMA) and reports the effects of organic surface modification on the rheology, suppression of settlement of filled systems, cure characteristics and final mechanical properties.

Synthesis and organic modification of CoAl2O4 nanocrystals under supercritical water conditions

The synthesis and in situ organic surface modification of cobalt aluminate nanoparticles were carried out to change the hydrophilic surface of pigment nanoparticles to hydrophobic by using organic reagents such as R-COOH and R-NH2 along with the respective metal hydroxide as starting materials at supercritical temperature, under 30–40 MPa pressure at a rapid reaction rate. The organic ligand capping could effectively inhibit the particle growth and also control the size of the nanocrystals. The resultant nanoparticles are dispersed in a binary solvent system, where organic modified particles are dispersed well in an upper organic solvent medium.

Surface organic modification of Fe 3O 4 nanoparticles by silane-coupling agents

Fe 3O 4 nanoparticles were prepared by chemistry co-precipitation and the mean crystal size was 17.9 nm measured by XRD. After it had been treated by silane-coupling agents KH570, magnetic microspheres dispersed in organic medium glycol were gained and the mean size of Fe 3O 4 nanopowders was 33.7 nm. So it can be concluded that magnetic micro-sphere is made of a few Fe 3O 4 crystals. Many factors of modification were researched, such as the time of ball milling, the content of Fe 3O 4 and the content of KH570. The modification of Fe 3O 4 is relative to the time of ball milling, but the dominant function is affected by the content of Fe 3O 4 and KH570. When the content of Fe 3O 4 is known, there is a suitable content of KH570. Different content of Fe 3O 4 will make the different suitable content of KH570, but the range of latter is less than former, which is relative to the distribution of KH570 on Fe 3O 4 surface or in the solution.

Supercritical hydrothermal synthesis of organic-inorganic hybrid nanoparticles

We have developed supercritical hydrothermal synthesis method of metal oxide nanoparticles where metal salt aqueous solution is mixed with high temperature water to rapidly increase the temperature of the metal salt solution and thus reduce the reactions and crystallizations during the heating up period. By using this method, we succeeded in the continuous and rapid production of metal oxide nanocrystals. A new method proposes to synthesize organic-inorganic fused materials based on the methods of supercritical hydrothermal synthesis. By introducing organic materials in a reaction atmosphere of supercritical hydrothermal synthesis, we successfully synthesized metal oxide nanoparticles whose surface was modified with organic materials. In supercritical state, water and organic materials form a homogeneous phase, which provides an excellent reaction atmosphere for the organic modification of nanoparticles. Modification with bio-materials including amino acids was also possible. By changing organic modifiers, particle morphology and crystal structure were changed. This organic surface modification provides a various unique characteristics for the nanoparticles: Dispersion of nanoparticles in aqueous solutions, organic solvents or in liquid polymers can be controlled by selecting hydrophilic or hydrophobic modifiers.

Surface organic modification of inorganic substrates by plasma deposition of tin oxide organic-like thin films and grafting polymerization

The plasma deposition and surface grafting polymerization have been used to modify the surface structure and properties of inorganic substrates such as organic nature, structural constitution, hydrophilicity, functional groups, and conductivity. In this study, tin oxide (SnO x ) organic-like thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) of tetramethyltin (TMT) and O 2 gas mixtures at low temperature. Higher proportion of TMT in the TMT/O 2 mixtures tends to increase organic nature of the deposited films and makes the surface hydrophobic. The organic-like thin films containing peroxides or free radicals can be subsequently grafted hydrophilic polymer acrylamide (AAm) by UV-induced grafting polymerization.

Windowless argon excimer source for surface modification

Abstract The article describes applications of a novel windowless argon excimer source for surface modification. Experimental results on etching of polymeric surfaces, degradation of organic surface residues, surface activation and modification of gas permeability and selectivity of polymeric membranes are presented. Moreover, radical formation from the excimer source and surface curing of liquid acrylates are examined. Typical treatment times are in the range of minutes for photolytic decomposition effects and seconds for UV curing effects. The surface modification effects induced by the argon excimer source were analysed by XPS, ESR, IR-spectroscopy, white light reflection spectroscopy, scanning electron microscopy, micro-hardness and permeation measurements.

Organic Surface Modification of TEOS Based Silica Aerogels Synthesized by Co-Precursor and Derivatization Methods

The experimental results on the organic modification of tetraethoxysilane (TEOS) based silica aerogels synthesized by co-precursor and derivatization methods are reported and discussed. In order to obtain silica aerogels with better physicochemical properties in terms of higher hydrophobicity, optical transmission and thermal stability, eight organosilane compounds (hydrophobic reagents) of the type RnSiX4−n have been used. The molar ratio of tetraethoxysilane (TEOS), ethanol (EtOH), water (0.001 M oxalic acid catalyst) was kept constant at 1:5:7 respectively. The organically modified silica aerogels were produced by two different methods: (i) Co-precursor method and (ii) Derivatization method. In the former method, the molar ratio of hydrophobic reagent (HR) to TEOS was varied from 0.1 to 0.6. In the later method, derivatization of the wet gels was carried out using 20% hydrophobic reagent in methanol. The merits and demerits of both these methods have been presented. The organic surface modification of the aerogels was confirmed by the Fourier Transform Infrared (FTIR) spectroscopic studies and the contact angle measurements. In the co-precursor method, with the increase in hydrophobic reagent/TEOS molar ratio, the hydrophobicity increases (θ = 136°) and the optical transmission decreases (≈5%), whereas in the derivatization method the optical transmission is very high (T ≈ 85%) but the hydrophobicity is low (θ = 120°). The thermal stability of the hydrophobic aerogels (the temperature up to which the hydrophobicity is retained) was studied in the temperature range of 25–800°C. The aerogels based on the co-precursor method retained the hydrophobicity up to a temperature as high as 520°C and on the other hand, the derivatized aerogels are hydrophobic only up to a temperature of 285°C. For the first time, TEOS based hydrophobic silica aerogels have been obtained with negligible volume shrinkage using the trimethylethoxysilane (TMES) co-precursor. The aerogels were characterized by Fourier transform infrared spectroscopy (FTIR), optical transmittance, Scanning Electron Microscope (SEM), thermogravimetric (TG) and differential thermal (DT) analyses and the contact angle measurements.