Novel Method Of Surface Modification Research Articles

Improved NO2 gas-sensing performance of PPy by hydrogen plasma treatment: Experimental study and DFT verification

Improving gas selectivity and stability poses a challenge for gas sensors based on polypyrrole (PPy). Radio frequency hydrogen plasma was employed to modify the surface of PPy nanosheet. PPy treated with hydrogen plasma owns a larger specific surface area and an increased concentration of surface hole carriers due to the dispersion of hydrogen plasma, which results in excellent nitrogen dioxide (NO2) gas sensing performance for the PPy sensor. Furthermore, the increased electronic transfer ability and NO2 adsorption capacity of the PPy treated by hydrogen plasma were confirmed based on the calculations of Density Functional Theory (DFT). The stronger interaction of PPy treated with hydrogen plasma between PPy and NO2 have happened comparing to untreated PPy. PPy/H sensor shows a magnificent NO2 gas sensing performance (sensitivity and selectivity) due to the strong interaction (strong adsorption ability and electron transfer) between PPy and NO2 caused by the hydrogen plasma treatment. Organic semiconductor treatment with hydrogen plasma offers a novel method for surface modification of PPy applied to gas sensing.

Enhancing the Electrochemical Performance of High Voltage LiNi0.5Mn1.5O4 Cathode Materials by Surface Modification with Li1.3Al0.3Ti1.7(PO4)3/C.

A novel method for surface modification of LiNi0.5Mn1.5O4 (LNMO) was proposed, in which a hybrid layer combined by Li1.3Al0.3Ti1.7(PO4)3 (LATP) and carbon (C) composite on LNMO material were connected by lithium iodide. Structure and morphology analyses illustrated that a higher contact area of active substances was achieved by the LATP/C composite layer without changing the original crystal structure of LNMO. XPS analysis proved that I- promoted the reduction of trace Mn4+, resulting in a higher ion conductivity. Galvanostatic charge-discharge tests exhibited the capacity of the LNMO with 5% LATP/C improved with 35.83% at 25 °C and 95.77% at 50 °C, respectively, compared with the bare after 100 cycles, implying the modification of high-temperature deterioration. EIS results demonstrated that one order of magnitude of improvement of the lithium-ion diffusion coefficient of LATP/C-LNMO was achieved (3.04 × 10-11 S cm-1). In conclusion, the effective low-temperature modification strategy improved the ionic and electronic conductivities of the cathode and suppressed the side reactions of high-temperature treatment.

Construction of high-performance ZnO/C/Bi<sub>2</sub>O<sub>3</sub> composites and their application in NiZn battery

<p indent="0mm">The zinc anode easily encounters some problems such as dendrite growth, shape change, and hydrogen evolution during the charge-discharge process, which lead to the poor cycle life of NiZn battery. To solve these problems, a novel method for surface modification of ZnO was proposed. By using PVA as carbon source, ZnO/C composite was first synthesized; and then, ZnO/C/NH₄Bi₃F₁₀ composite was prepared in the ethylene glycol; ZnO/C/ NH₄Bi₃F₁₀ finally transformed into ZnO/C/Bi₂O₃ after being calcined at high temperature. X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and elemental distribution mapping results confirmed the successful synthesis of ZnO/C/Bi₂O₃ composites. The formation mechanism of the composites was discussed in detail. Cyclic voltammetry (CV), electrochemical impedance spectrosocopy (EIS) and constant current charge-discharge tests showed that ZnO/C/Bi₂O₃ composite with the Bi₂O₃ content of 2% displayed the highest electrochemical activity. Furthermore, the NiZn battery assembled from the composite with 2 wt% Bi₂O₃ displayed a cycle life up to 1806 times with the highest energy density of 166.5 Wh kg⁻¹. The energy density of 164.44 Wh kg⁻¹ and Coulombic efficiency of 90% were still maintained after 1806 cycles. The as-prepared ZnO/C/Bi₂O₃ composites exhibit excellent electrochemical performance and great potential for practical applications. This innovative synthesis method is hopeful to be extended to prepare other composites.

Novel Transparent TiO2/AgNW-Si(NH2)/PET Hybrid Films for Flexible Smart Windows.

The application of flexible indium tin oxide (ITO)-free electrochromic devices (FCDs) has always been a research hotspot in flexible electronics. Recently, a silver nanowire (AgNW)-based transparent conductive film has raised great interest as an ITO-free substrate for FCDs. However, several challenges, such as the weak binding of AgNWs to the substrate, high junction resistance, and oxidation of AgNWs, remain. In this paper, a novel method for surface modification of AgNWs with N-aminoethyl-γ-aminopropyltrimethoxysilane [Si(NH2)] solution is proposed to enhance the bonding with the flexible substrates and the active materials, thereby inhibiting the delamination of AgNWs from the substrate and reducing the high junction resistance between nanowires. The TiO2/AgNW-Si(NH2)/poly(ethylene terephthalate) (PET) films show outstanding mechanical properties, of which the resistance remains almost unchanged after mechanical bending of 5000 cycles (ΔR/R0 ≈ 3.6%) and repeated peeling off cycles with 3M tape 100 times (ΔR/R0 ≈ 6.0%). In addition, we found that the oxygen-containing groups on the TiO2/AgNW-Si(NH2)/PET surface form hydrogen bonds with the TiO2 sol, resulting in tight contact between the TiO2 sol and the AgNWs, which prevents the AgNWs from oxidation. As a result, the TiO2/AgNW-Si(NH2)/PET film exhibited long-time aging (ΔR/R0 ≈ 4.9% in the air for 100 days) stability. A FCD was constructed with the TiO2/AgNW-Si(NH2)/PET film, which showed excellent electrochromic performance (94% retention) after 5000 bending cycles, indicating high stability and mechanical flexibility. These results present a promising solution to the transparent conductive films for flexible energy devices.

Surface Modification of Alginate Microcarriers for Improvement of Their Biological Properties.

The obtaining of microcarriers for the cell culture and delivery is an urgent task of tissue engineering and regenerative medicine. The novel method of surface modification of alginate microcarriers in the form of microspheres with a diameter of 200-300 μm was developed. The described method consists in covalent crosslinking between collagen and surface of alginate microcarriers. It was shown that the method makes it possible to completely modify the surface of the alginate microcarrier, which can be used to improve the biological properties of the microcarrier. Such microcarriers with improved biological properties can be considered as effective systems for cell delivery and culture.

A novel method of surface modification by electrochemical deoxidation: Effect on surface characteristics and initial bioactivity of zirconia.

The aim of this study was to investigate and compare the surface characteristics and initial bioactivity of ceria-stabilized zirconia/alumina nanocomposite (NANOZR) with those of yttria-stabilized zirconia (3Y-TZP) and pure titanium (CpTi) following the use of three surface modification methods; polishing, sandblasting/acid-etching (SB-E) and electrochemical deoxidation (ECD). Physical properties including surface morphology, chemical composition, X-ray diffraction, surface wettability, surface roughness, and hardness were measured. Osteoblast-like MC3T3-E1 cells were used to examine cell morphology and attachment to the surfaces of the materials. ECD treated NANOZR (NANOZR-E) showed a well-arranged, self-organized microporous surface structure with significantly low contact angles when compared with the other specimens (p < 0.05). NANOZR-E also demonstrated a slight decrease in monoclinic phase content (-4.4 wt %). The morphology and attachment of MC3T3-E1 cells on NANOZR-E were similar to those on polished and SBE-treated CpTi surfaces. Higher cell affinity was observed on NANOZR-E when compared with ECD treated 3Y-TZP. The findings of this study indicate the effectiveness of the novel technique, ECD, in the formation of a microporous surface on NANOZR when compared with both CpTi and 3Y-TZP. Moreover, this method also appears to improve the biological activity of NANOZR during the initial stage. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2641-2652, 2017.

Improvement of filling bismuth for x-ray absorption gratings through the enhancement of wettability

Filling materials with high x-ray linear absorption coefficients in high aspect-ratio (HAR) structures is a key process for the fabrication of absorption gratings used in x-ray differential phase-contrast imaging. Bismuth has been chosen as an effective filling material in micro-casting technology, because of its low cost both in price and facility use. However, repellence on structure surfaces against molten bismuth leads to an obstacle in terms of completely filling bismuth into the small-aperture and HAR microstructure formed by photo-assisted electrochemical etching in 5 inch silicon wafers. We propose and implement a novel method of surface modification to completely fill bismuth into these structures with periods of 3 μm and 42 μm, respectively, and as deep as 150 μm. The modified surface with a Bi2O3 layer covering the structure surface, including the side walls, induces an enhanced bismuth filling ratio. The superiority of the method is demonstrated by micrographs which show filled microstructures compared to the previously used method, where only a layer of 100 nm SiO2 was covered. Furthermore, we have observed that the improved micro-casting makes the absorption gratings clean surfaces, and no post treatment is needed.

Organic solvent nanofiltration with Grignard functionalised ceramic nanofiltration membranes

In this paper the use of functionalised ceramic nanofiltration membranes in solvent filtration is described. The membranes were grafted using a novel method for surface modification based on Grignard chemistry. Commercially available 1nm TiO2 membranes were differently functionalised with a series of alkyl groups (methyl, pentyl, octyl, dodecyl) in order to generate a more hydrophobic membrane surface.The properties of the modified membranes were examined by physico-chemical characterisation (contact angle measurements, micro-ATR/FTIR-spectroscopy) in addition to performance characterisation (flux measurements for solvents ranging from highly polar to non-polar, next to polyethylene glycol retentions in water and polystyrene retentions in acetone). All observations for modified membranes are consistent with the assumed partial replacement of the OH-groups on the membrane surface and the consequent amphiphilic character of the modified membrane surface.The retentions of modified and unmodified membranes in acetone confirm the recent findings in organic solvent nanofiltration (OSN): an increase in the hydrophobicity of the membrane leads to an increase in the retentions.A comparison with reference polymeric membranes shows that the newly developed membranes are a good alternative, having the advantage of the absence of effects of swelling. This new grafting technique for ceramic membranes allows to further explore solvent–membrane–solute interactions in OSN in a controlled way without the extra complexity of swelling.

CdTe Quantum Dots Embedded in Multidentate Biopolymer Based on Salep: Characterization and Optical Properties

This paper describes a novel method for surface modification of water soluble CdTe quantum dots (QDs) by using poly(acrylic acid) grafted onto salep (salep-g-PAA) as a biopolymer. As-prepared CdTe-salep-g-PAA QDs were characterized by Fourier transform infrared (FT-IR) spectrum, thermogravimetric (TG) analysis, and transmission electron microscopy (TEM). The absorption and fluorescence emission spectra were measured to investigate the effect of salep-g-PAA biopolymer on the optical properties of CdTe QDs. The results showed that the optical properties of CdTe QDs were significantly enhanced by using salep-g-PAA-based biopolymer.

A novel method for surface modification of nanoparticles based on control of charge environment

A novel procedure for surface modification of SiO2 nanoparticles is described. Tetraoctylammonium bromide was introduced to modification system for the purpose of controlling the surface charge environment of SiO2 nanoparticles. Then, the SiO2 nanoparticles were treated with the coupling agents firstly, followed by radical grafting polymerization in non-aqueous system to graft Poly (methyl methacrylate) chains onto the surface of modified SiO2 nanoparticles. Fourier transform infrared spectroscopy, thermogravimetric analysis, high-resolution X-ray photoelectron spectra, and 13C nuclear magnetic resonance were used to characterize the modification effect of SiO2 nanoparticles. The results indicated that the method we described is an effective way to modify the surface of nanoparticles. And the morphology and characteristic of SiO2 nanoparticles were characterized by transmission electron microscopy (TEM), quasielastic laser light scattering (QELS), dynamic contact angle. The results of TEM and QELS demonstrated that nanosilica with an average size of 85.8 nm was prepared. The reduction of the contact angle indicated the increase in hydrophobicity of nanosilica. The result of controlling the surface charge environment of SiO2 nanoparticles was characterized by zeta potential. By using this modification method, nanoparticles are of great potential to synthesize versatile organic/inorganic nanocomposite.

Corrosion resistance enhancement of Ti–47Al–2Cr by thermal treatment in a controlled atmosphere

PurposeThe purpose of this paper is to investigate the effect of thermal treatment at low partial pressure of oxygen on electrochemical corrosion resistance of Ti‐47Al‐2Cr (at %) intermetallic, known as γ‐TiAl alloy.Design/methodology/approachThe surfaces of the samples were modified by thermal treatment at different temperatures in N2 gas flow for an hour. Characterization of the modified surface layers was carried out by microscopic examinations, hardness and roughness tests, and X‐ray diffraction analyses. Potentiodynamic polarization was used to evaluate the corrosion performance of γ‐TiAl in Ringer's solution.FindingsThe results indicated that the alloy treated at 950 °C had the optimum corrosion resistance, which can be attributed to the formation of an oxide layer by the surface thermal treatment and increase of the passive layer thickness.Practical implicationsLow corrosion rate (CR), high pitting potential (Epit), and more noble corrosion potential (Ecorr) make it possible for γ‐TiAl to be considered as a candidate for biomedical applications.Originality/valueThe treatment described in the paper is a novel method for surface modification of this type of alloy and results showed that it was an effective treatment and that the corrosion resistance improved remarkably.

A novel method of surface modification to polysulfone ultrafiltration membrane by preadsorption of citric acid or sodium bisulfite

In membrane processes, various agents are used to enhance, protect, and recover membrane performance. Applying these agents in membrane modification could potentially be considered as a simple method to improve membrane performance without additional process. Citric acid (CI) and sodium bisulfite (SB) are two chemicals that are widely used in membrane feed water pretreatment and cleaning processes. In this work, preadsorptions of CI and SB were developed as simple methods for polysulfone ultrafiltration membrane modification. It was found that hydrogen bonding and Van Der Waals attraction could be responsible for the adsorptions of CI and SB onto membranes, respectively. After modification with CI or SB, the membrane surfaces became more hydrophilic. Membrane permeability improved when modified by SB while decreased a little when modified by CI. The modified membranes had an increase in PEG and BSA rejections and better antifouling properties with higher flux recovery ratios during filtration of a complex pharmaceutical wastewater. Moreover, membrane chlorine tolerance was elevated after modification with either agent, as shown by the mechanical property measurements.

Novel Method for Surface Modification of Silicone-containing Hydrogel Using Addition Reaction

Abstract We designed a novel surface modification method of shaped articles from silicone-containing hydrogel using hydrosilylation reaction between silicone component and poly(ethylene glycol) (PEG) chain in order to improve the surface wettability. For the introduction of –SiH group to hydrogel, in addition to copolymerization of –SiH-containing methacrylate, argon gas plasma treatment was found to be effective. Hydrosilylation reaction between shaped article and PEG easily proceeded in organic solvent, and the resultant hydrogel showed reduced contact angle after the hydration in water. FTIR-ATR measurement suggested the validity of our process design concept.

Hierarchical titanium surface textures affect osteoblastic functions

This study investigated the surface characteristics and in vitro cytocompatibility of hierarchical textured titanium surfaces with nanograins and microroughness, produced by surface mechanical attrition treatment (SMAT). The surface characteristics were evaluated by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, contact angle, and surface energy measurements. The in vitro cytocompatibility of the SMAT processed surfaces (hereafter Ti-SMAT surfaces) were assessed in terms of cellular attachment, morphology, viability, alkaline phosphatase (ALP) activity, and mRNA gene expression. Two other titanium surfaces were compared: well-polished Ti6Al4V surfaces (hereafter Ti-polish surfaces) and thermally sprayed rough surfaces (hereafter Ti-spray surfaces). The Ti-SMAT surfaces showed a higher hydrophilicity and increased surface energy compared with the Ti-polish and Ti-spray surfaces. Consequently, these Ti-SMAT surfaces demonstrated enhancement of cell attachment, spreading, viability, and ALP activity. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed significantly higher ALP activity and stronger expression of mRNA levels of key osteoblast genes in cells grown on the Ti-SMAT surfaces than the other two surfaces. These results reveal a synergic role played by nanostructure and microtopography in osteoblastic functions and demonstrate the more promising cytocompatibility of the hierarchical textured surfaces. It is suggested that the SMAT process may provide a novel method of surface modification to the currently available metallic biomaterials.

Bifunctional Nanoparticles with Fluorescence and Magnetism via Surface-Initiated AGET ATRP Mediated by an Iron Catalyst

Fluorescent/magnetic nanoparticles are of interest in many applications in biotechnology and nanomedicine for its living detection. In this study, a novel method of surface modification of nanoparticles was first used to modify a fluorescent monomer on the surfaces of magnetic nanoparticles directly. This was achieved via iron(III)-mediated atom-transfer radical polymerization with activators generated by electron transfer (AGET ATRP). Fluorescent monomer 9-(4-vinylbenzyl)-9H-carbazole (VBK) was synthesized and was grafted from magnetic nanoparticles (ferroferric oxide) via AGET ATRP using FeCl(3)·6H(2)O as the catalyst, tris(3,6-dioxaheptyl)amine (TDA-1) as the ligand, and ascorbic acid (AsAc) as the reducing agent. The initiator for ATRP was modified on magnetic nanoparticles with the reported method: ligand exchange with 3-aminopropyltriethoxysilane (APTES) and then esterification with 2-bromoisobutyryl bromide. After polymerization, a well-defined nanocomposite (Fe(3)O(4)@PVBK) was yielded with a magnetic core and a fluorescent shell (PVBK). Subsequently, well-dispersed bifunctional nanoparticles (Fe(3)O(4)@PVBK-b-P(PEGMA)) in water were obtained via consecutive AGET ATRP of hydrophilic monomer poly(ethylene glycol) methyl ether methacrylate (PEGMA). The chemical composition of the magnetic nanoparticles' surface at different surface modification stages was investigated with Fourier transform infrared (FT-IR) spectra. The magnetic and fluorescent properties were validated with a vibrating sample magnetometer (VSM) and a fluorophotometer. The Fe(3)O(4)@PVBK-b-P(PEGMA) nanoparticles showed an effective imaging ability in enhancing the negative contrast in magnetic resonance imaging (MRI).

Improvement of surface bioactivity of poly(lactic acid) biopolymer by sandblasting with hydroxyapatite bioceramic

This study communicates a simple and effective method for modification of the surface of synthetic biopolymer poly(lactic acid) (PLA) with bioactive ceramic hydroxyapatite (HA) using a sandblasting technique. The sandblasting particles were bombarded onto the PLA, covering the surface quite evenly. The HA-sandblasted PLA showed good in vitro apatite forming ability in a simulated body fluid within a few days, which was rarely observed for pure PLA. Moreover, the HA-sandblasted PLA enhanced the initial cell adhesion and further proliferation, and up-regulated bone cell functions such as the alkaline phosphatase activity. This novel method of surface modification of the biopolymer with bioactive ceramic has the potential for use in developing bone bioactive implantable materials.

Synthesis of polyacrylonitrile-grafted cross-linked N-chlorosulfonamidated polystyrene via surface-initiated ARGET ATRP, and use of the resin in mercury removal after modification

A novel method of surface modification was developed via iron (III)-mediated atom transfer radical polymerization, with activators regenerated by electron transfer (ARGET ATRP) on the surfaces of polystyrene resin-supported N-chlorosulfonamide groups. The well-defined polyacrylonitrile (PAN) was grafted onto the surfaces of the polystyrene (PS). The graft reaction exhibited first-order kinetics with respect to the polymerization time in the low-monomer-conversion stage. The cyano group of PAN-g-PS was modified by NH2OH·HCl to yield amidoxime (AO) groups. The AO groups had been demonstrated to be an efficient Hg-specific sorbent, which can remove Hg2+ from solutions. No interference arose from common metal ions, such as Pd2+, Ag+, and Cu2+. Three adsorption–desorption cycles demonstrated that this resin is suitable for reuse without any considerable change in adsorption capacity.

Self-organization of dipeptide-grafted polymeric nanoparticles film: A novel method for surface modification

Novel dipeptide-grafted polymeric nanoparticles were prepared by grafting the dipeptide (Gly-Gly) to a block copolymer backbone, comprised of styrene-alt-(maleic anhydride) and styrene. In aqueous solution PSt 130-b-P(St-alt-MAn) 58-g-GlyGly 26 formed stable dispersed spherical aggregates of ca. 75 nm. The critical micelle concentration for the dipeptide-grafted block copolymer self-aggregates was 6.3 × 10 −3 mg mL −1. The zeta-potential of the aggregates was estimated experimentally. The dispersed polymer nanoparticles effectively self-organized to form stable nanoparticle thin films on hydrophobic solid surfaces, such as octadecyltrichlorosilane modified glass (OTS-G). As the ionic strength and temperature of the polymer suspension increased the surface coverage of the nanoparticle film increased and its hydrophobicity (water contact angle) decreased. Significantly less bovine serum albumin (BSA) adsorbed to nanoparticles modified surfaces with compared OTS-G surfaces. Diglycine grafted polymer nanoparticles have the potential to be used as a novel platform to study protein–protein interactions and to control fouling.

Surface modification of UV-cured epoxy resins by click chemistry

A novel method for surface modification of UV-cured epoxy network was described. Photoinitiated cationic copoly- merization of a bisepoxide, namely 3,4-epoxy cyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (EEC) with epibromohydrine (EBH) by using a cationic photoinitiator, (4-(2-methylpropyl)- phenyl)4-methylphenyl-iodonium hexafluorophosphate, in pro- pylene carbonate solution was studied. The real-time Fourier transform infrared spectroscopic, gel content determination and thermal characterization studies revealed that both EEC and EBH monomers take part in the polymerization and epoxy network possessing bromomethyl functional groups was obtained. The bromine functions of the cured product formed on the glass sur- face were converted to azide functionalities with sodium azide. Independently prepared alkyne functional poly(ethylene glycol) (PEG) was subsequently anchored to azide-modified epoxy sur- face by a ''click'' reaction. Surface modification of the network through incorporation of hydrophilic PEG chain was evidenced by contact angle measurements. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2862-2868, 2010

A novel method of surface modification on thin-film-composite reverse osmosis membrane by grafting hydantoin derivative

Membrane degradations by biofouling and free chlorine oxidation are the major obstacles for aromatic polyamide thin-film-composite (TFC) reverse osmosis (RO) membranes to realize high performance over a long period of operation. In this work, a hydantoin derivative, 3-monomethylol-5,5-dimethylhydantoin (MDMH), was grafted onto the nascent aromatic polyamide membrane surfaces by the reactions with active groups (e.g., acyl chloride groups) in the surfaces. The grafted MDMH moieties with high reaction activity and free chlorine could play as sacrificial pendant groups when membranes suffer from chlorine attacks, and the chlorination products N-halamines with strong antimicrobial function could sterilize microorganisms on membrane surfaces and then regenerate to MDMH. This was designed as a novel means to improve both chlorine resistances and anti-biofouling properties of the aromatic polyamide TFC RO membranes. Attenuated total reflectance mode Fourier transform infrared spectroscopy (ATR-FTIR) revealed that the MDMH-modified membranes had two characteristic bands at 1772 and 1709 cm −1 corresponding to two carbonyl groups in hydantoin ring. This suggested the successful grafting of MDMH onto the membrane surfaces, which was further confirmed and quantified by X-ray photoelectron spectroscopy (XPS) analysis. After modification with MDMH, the membrane surface hydrophilicity increased obviously as contact angles decreased from 57.7° to 50.4–31.5°. But, there was no obvious change in membrane surface roughness after modification. The MDMH-modified membranes were shown to possess high chlorine resistances with small changes in water fluxes and salt rejections after chlorination with 100–2000 ppm h chlorine at pH 4. The chlorinated MDMH-modified membranes demonstrated obvious sterilization effects on Escherchia coli and substantial preventions against microbial fouling. Therefore, the MDMH-modified membranes offer a potential use as a new type of chlorine resistance and anti-biofouling TFC RO membranes.