Surface Modification Of Zinc Oxide Research Articles

Surface modification of zinc oxide and its application in polypropylene with excellent fire performance and ultra-violet resistance

Despite the advantages of easy moulding and excellent mechanical properties, there are still some shortcomings with polypropylene (PP) such as high flammability and poor ultra-violet (UV) resistance. In this work, modified zinc oxide (mZnO) was prepared by reacting zinc oxide nanoparticles (ZnO) with polysiloxanes, and the effect of mZnO on the effectiveness of intumescent flame-retardant and on the UV aging resistance of polypropylene were investigated. By introducing 16 wt% (intumescent flame-retardant /mZnO) and 0.3 wt% maleic anhydride-grafted PP (MAH-g-PP), the limiting oxygen index increased to 32.7 %, and passed UL-94V-0 rating. In comparison to the controls, the peak heat release rate and the peak smoke release rate were 88.5 % and 80 % lower, respectively. In addition, PP samples showed improved mechanical properties, with a 5 % increase in tensile properties compared to the pure PP sample. After 100 h of UV irradiation, the surface of the samples was relatively flat and smooth, and the carbonyl index decreased from 81.1 of neat PP to 26.7. PP composites with 100 h aging treatment still had excellent flame retardancy and mechanical properties. The results showed that mZnO was effective in improving the flame retardancy, mechanical properties and light aging tolerance of PP. This study provides a novel approach to fabricate long-life flame-retardant PP composites with low additive content.

Improvement of absorbing stability of carbon nanofibers in sub-terahertz domain using the surface modification of zinc oxide

Carbon nanofibers (CNFs) is a typical electrical loss material with strong permittivity that has been widely used in the field of electromagnetic shielding, attenuation, and reception. However, studies have demonstrated that the unstable anisotropic EM behavior exhibited by CNFs in the terahertz domain hinders its application in the tremendously high frequency domain. In this study, ZnO is used to perform surface modification of CNFs based on the sputtering method, which effectively eliminate the anisotropic EM behavior of CNFs at different irradiation angles in the sub-terahertz band. ZnO coated the surface of fiber wall comprehensively in the form of nano-scale. The results show that after the surface modification, the composite sample exhibits a stable isotropic EM response in the sub-terahertz band of 500–750 GHz. Also, in the frequency range of 551–563 GHz (bandwidth: 12 GHz), ZnO not only acts as a stabilizer, but also enhances the absorption performance of the original CNFs by 6%, which is up to 92%. In the frequency range of 660–690 GHz (bandwidth: 30 GHz), the composite sample and the pure CNFs sample have similar wave absorption performance with about 75%, the maximum difference is less than 5%, and the minimum is about 2.6%.

Improving the Efficiency of Organic Solar Cells with Methionine as Electron Transport Layer.

Interface modification is an important way to get better performance from organic solar cells (OSCs). A natural biomolecular material methionine was successfully applied as the electron transport layer (ETL) to the inverted OSCs in this work. A series of optical, morphological, and electrical characterizations of thin films and devices were used to analyze the surface modification effects of methionine on zinc oxide (ZnO). The analysis results show that the surface modification of ZnO with methionine can cause significantly reduced surface defects for ZnO, optimized surface morphology of ZnO, improved compatibility between ETL and the active layer, better-matched energy levels between ETL and the acceptor, reduced interface resistance, reduced charge recombination, and enhanced charge transport and collection. The power conversion efficiency (PCE) of OSCs based on PM6:BTP-ec9 was improved to 15.34% from 14.25% by modifying ZnO with methionine. This work shows the great application potential of natural biomolecule methionine in OSCs.

Influence of surface modification of zinc oxide on physical properties of high density polyethylene

Inorganic nanofillers have sparked important research in the field of polymer nanocomposites because they can improve the properties of polymers. Hydrophobic ZnO nanoparticles modified by oleic acid (OA) were designed and prepared to accelerate the dispersion state of ZnO in the high viscosity polyethylene (HDPE), and enhance the performance of HDPE. HDPE/ZnO nanocomposites with different kinds and fractions of ZnO were further prepared via melt mixing method. The result showed the hexagonal and spindle-like ZnO nanoparticles with size distribution of 150–300 nm was acquired in the absence and presence of OA. Compared with surface untreated ZnO (U-ZnO), ZnO nanoparticles modified by OA (O-ZnO) can disperse evenly into HDPE at the fraction of O-ZnO below 5 wt%. TG data showed the presence of nanosized U-ZnO and O-ZnO in HDPE can significantly enhance the thermal stability of HDPE through raising the activation energy of HDPE in thermal decomposition process. The thermal decomposition order (n) for HDPE/ZnO nanocomposites was mostly bigger than that of HDPE, demonstrating the decomposition mechanism for HDPE became more complicated because of the addition of ZnO nanoparticles. DSC data showed U-ZnO nanoparticles cannot accelerate nucleation of HDPE and seemed to postpone the crystallization process, and O-ZnO nanoparticles was heterogeneous nucleating agent for HDPE. Moreover, the tensile and impact strength of HDPE was improved by the addition of O-ZnO, and connected with the dispersion state of ZnO nanoparticles in HDPE. The improvement in thermal stability, crystallization and mechanical properties by adding ZnO into HDPE matrix significantly enhance the potential of HDPE in food packaging, electronic packaging, drug and pharmaceutical bottles.

Preparation of ZnO nanoparticles modified with silane coupling-agents to fabricateanti-UV Poly(vinyl chloride) films

The uses of inorganic metal oxide as ultraviolet (UV) absorbers have potential to increase the production of UV protection and can also overcome the disadvantages of organic molecules. In this article, we report an effective technique to fabricating polyvinyl chloride (PVC) films with well UV shielding efficiency. Surface modification of zinc oxide (ZnO) nanoparticles (NPs) with different silane coupling-agents were achieved, and through solution casting technique dispersed within the PVC matrix. Infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and UV spectrophotometer were applied to study the structures, dispersions, and optical properties. The results showed that the functionalized ZnO NPs could be well dispersed in PVC and endow the polymer composite films with significantly improved anti-UV capability. The facile processing and obtained properties of PVC composites have shown potential for low cost and environmentally sustainable applications in the UV protection field.

Preparation of ZnO nanoparticles modified with silane coupling-agents to fabricate anti-UV Poly(vinyl chloride) films.

The uses of inorganic metal oxide as ultraviolet (UV) absorbers have potential to increase the production of UV protection and can also overcome the disadvantages of organic molecules. In this article, we report an effective technique to fabricating polyvinyl chloride (PVC) films with well UV shielding efficiency. Surface modification of zinc oxide (ZnO) nanoparticles (NPs) with different silane coupling-agents were achieved, and through solution casting technique dispersed within the PVC matrix. Infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and UV spectrophotometer were applied to study the structures, dispersions, and optical properties. The results showed that the functionalized ZnO NPs could be well dispersed in PVC and endow the polymer composite films with significantly improved anti-UV capability. The facile processing and obtained properties of PVC composites have shown potential for low cost and environmentally sustainable applications in the UV protection field.

Facile preparation PCL/ modified nano ZnO organic-inorganic composite and its application in antibacterial materials

Due to its good biodegradability and biocompatibility, polycaprolactone (PCL) has attracted widespread attention in the field of biomedical materials. Incorporation of Zinc oxide (ZnO) into PCL has been proved an effective way to improve its antibacterial properties. However, the interfacial compatibility of the organic-inorganic system needs to be improved due to the agglomeration of nanoparticles and phase separation of ZnO and PCL matrix affect its antibacterial efficiency. In this research, the ZnO surface was modified with citric acid monohydrate (CA) to improve the interfacial properties of ZnO-PCL system. The surface modification of ZnO was analyzed by DLS, TEM, TGA, and XPS. The results suggest that CA coating process can significantly reduce the agglomeration of ZnO nanoparticles and improve dispersion stability. The uniform PCL/ZnO-CA membranes with various nanofiller contents were fabricated through the solvent casting method. DSC and TGA analysis showed that the presence of ZnO-CA nanoparticles slightly decreased the crystallinity and thermal stability of the polymer. And ZnO-CA loaded improved the mechanical properties and wettability of the composite PCL membranes. Moreover, the composite PCL membranes showed good antibacterial activity against both E. coli and S. aureus while exhibiting good cytocompatibility, which indicated that the antibacterial and no cytotoxicity biomaterials had promising application in the biomedical field.

Impact of co-mixing technique and surface modification of ZnO nanoparticles using stearic acid on their dispersion into HDPE to produce HDPE/ZnO nanocomposites

In this article, the effectiveness of the co-mixing processing technique and surface modification of zinc oxide (ZnO) filler on the characteristics of the developed high-density polyethylene (HDPE)/ZnO was investigated. ZnO was treated and co-mixed with stearic acid (SA) at a ratio of 50/50 wt% using kitchen coffee grinder and the mixture was then added to the HDPE matrix in a Brabender plastograph with various ZnO contents of 0.5, 1 and 2 wt%. The morphology of the nanocomposites was characterized using scanning electron microscopy (SEM). The micrographs showed well and uniform dispersion of both treated and untreated ZnO nanofiller; however, the treated ZnO particles showed better dispersion. The nanocomposite containing 1 wt% ZnO nanoparticles was found to have the optimal properties. The results of the SEM were supported by the atomic force microscopic technique. The uniform dispersion of ZnO was further investigated through X-ray diffraction spectra. The minor peaks of ZnO in the HDPE/treated and untreated ZnO nanocomposites are considered as an evidence for the presence of uniform and well-dispersed ZnO. The electrical conductivity of the nanocomposite samples is higher than that of neat HDPE due to the semiconducting nature of ZnO and increases with ZnO content. The results of this work proved that dispersibility can be achieved through the addition of SA and conductivity of the nanocomposite depends on the ZnO content. Moreover, co-mixing technique and the surface modification of the nanofillers are very effective in producing the HDPE/ZnO nanocomposites that have many potential industrial applications such as food packaging, drug and pharmaceutical bottles.

Self-assembly monolayers manipulate the power conversion processes in organic photovoltaics

Surface modification of zinc oxide (ZnO) plays a crucial role in enhancing the performance of organic photovoltaics (OPVs) due to its structure defect. Herein, methoxyphenylphosphonic acid (MPPA) modifier is introduced for interface engineering to improve the cell performance. The power conversion efficiency (PCE) of 11% has been achieved based on fullerene-free systems together with a breakthrough in current density. We obtain ZnO with reduced surface defect and lower work function after incorporation of MPPA modifier. Moreover, by analyzing dynamics process of solar cells, we discover MPPA modifier promotes the exciton generation, exciton diffusion, exciton dissociation and charge transport with reduced bimolecular recombination and trap-based recombination loss, leading to better power conversion processes.

Surface Modification of Zinc Oxide by 3-aminopropyltiethoxysilane and a Comparative Study of Effect of Corrosion on Carbon Steel With Epoxy Containing Graphene Oxide-Zinc Oxide (GO-ZnO) Hybrids

The use of coupling agent, 3-aminopropyltiethoxysilane (APTES) in the silanization reaction with metal oxides plays an important role to ensure that additional chemical modification can successfully be achieved. Studies have shown that introducing metal oxides onto graphene oxide sheets can improve the dispersion of sheets in a polymeric matrix, contributing to its excellent anti-corrosion properties. Hence, two methods of APTES attachment has been explored, where the first method utilizes a reflux process to introduce siloxane bonds to the ZnO NP surface; the latter usesuse of ultrasonication to stimulate the functionalization of ZnO NPs. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) were employed to characterize the APTES-Functionalized ZnO and the precipitation on the surface of GO sheets. The effect of GO-ZnO produced by the different types of functionalized ZnO on the corrosion protection and barrier performance of epoxy coating was investigated by electrochemical impedence spectroscopy (EIS). The results revealed that the long duration of reaction time provided by the reflux method managed to increase the number of siloxane bonds on the ZnO surface, allowing more amine groups to be attached onto the GO sheets and thus improve the corrosion resistance of epoxy.

ChemInform Abstract: Surface Structure Modification of ZnO and the Impact on Electronic Properties

AbstractReview: 232 refs.

Design and development of anisotropic inorganic/polystyrene nanocomposites by surface modification of zinc oxide nanoparticles

Anisotropic yolk/shell or Janus inorganic/polystyrene nanocomposites were prepared by combining miniemulsion polymerization and sol–gel reaction. The morphologies of the anisotropic composites were found to be greatly influenced by surface modification of zinc oxide (ZnO) nanoparticle seeds. Two different types of the oleic acid modified ZnO nanoparticles (OA-ZnO) were prepared by post-treatment of commercial ZnO powder and homemade OA-ZnO nanoparticles. The morphologies and properties of the nanocomposites were investigated by transmission electron microscope (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and energy dispersive X-ray spectroscopy (EDX). It was found that both post-treated OA-ZnO and in-situ prepared OA-ZnO nanoparticles resulted in the yolk–shell and Janus structure nanocomposites, but with varied size and morphology. These nanocomposites showed stable and strong fluorescence by introducing quantum dots as the co-seeds. The fluorescent anisotropic nanocomposites were decorated separately with surface carboxyl and hydroxyl groups. These composites with unique anisotropic properties will have high potential in biomedical applications, particularly in bio-detection.

Surface Structure Modification of ZnO and the Impact on Electronic Properties.

Zinc oxide (ZnO) is a widely utilized, versatile material implemented in a diverse range of technological applications, particularly in optoelectronic devices, where its inherent transparency, tunable electronic properties, and accessible nanostructures can be combined to confer superior device properties. ZnO is a complex material with a rich and intricate defect chemistry, and its properties can be extremely sensitive to processing methods and conditions; consequently, surface modification of ZnO using both inorganic and organic species has been explored to control and regulate its surface properties, particularly at heterointerfaces in electronic devices. Here, the properties of ZnO are described in detail, particularly its surface chemistry, along with the role of defects in governing its electronic properties, and methods employed to modulate the behavior of as-grown ZnO. An outline is also given on how the native and modified oxide interact with molecular materials. To illustrate the diverse range of surface modification methods and their subsequent influence on electronic properties, a comprehensive review of the modification of ZnO surfaces at molecular interfaces in hybrid photovoltaic (hPV) and organic photovoltaic (OPV) devices is presented. This is a case study rather than a progress report, aiming to highlight the progress made toward controlling and altering the surface properties of ZnO, and to bring attention to the ways in which this may be achieved by using various interfacial modifiers (IMs).

Influence of surface modification of zinc oxide nanoparticles on thermal behavior and hydrophilic property of PET–PEG composites

Zinc oxide (ZnO) nanoparticles were successfully prepared by a one‐step precipitation reaction in an aqueous solution of zinc acetate and sodium hydroxide with stearic acid (SA) as the modifying agent. Hydrophilic composites of poly(ethylene terephthalate) (PET), poly(ethylene glycol), and ZnO nanoparticles were prepared further by in situ polymerization. The surface modification of ZnO and the microstructure and properties of prepared nanoparticles were investigated by relative contact angle measurements (CA), Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), scanning electron microscopy, and thermogravimetric analysis (TGA). Measurements of CA and XRD indicated that the surface‐treated ZnO was hydrophobic and had a significant improvement in crystallinity with SA. Compared with the nanocomposites filled with the pure ZnO, the modified ZnO exhibits a better dispersion in PET–PEG matrix. TGA results showed that the presence of modified ZnO nanoparticles can improve the thermal stability of PET–PEG matrix. CA and low field nuclear magnetic resonance methods were used to investigate the hydrophilic behavior of nanocomposites. The results revealed that modified nanoparticles had a positive effect on the bound water absorption. A simple model for the interactions between ZnO, SA, and PET–PEG matrix was proposed. POLYM. COMPOS., 37:1830–1838, 2016. © 2015 Society of Plastics Engineers

Effect of surface modification and UVA photoactivation on antibacterial bioactivity of zinc oxide powder

The effects of surface modification of zinc oxide (ZnO) powder and UVA illumination on the powder towards Escherichia coli and Staphylococcus aureus were investigated. FESEM-EDS results showed that oxygen annealing increased the O:Zn ratio on the surface of ZnO-rod and ZnO-plate samples. Surface conductances of ZnO-rod and ZnO-plate pellets were reduced from 1.05nS to 0.15nS and 1.34nS to 0.23nS, respectively. Meanwhile, UVA illumination on the surface of the ZnO-rod and ZnO-plate samples was found to improve surface conductance to 7.08nS and 6.51nS, respectively, due to the release of charge carrier. Photoluminescence results revealed that oxygen annealing halved the UV emission intensity and green emission intensity, presumably caused by oxygen absorption in the ZnO lattice. The antibacterial results showed that oxygen-treated ZnO exhibited slightly higher growth inhibition on E. coli and S. aureus compared with unannealed ZnO. UVA illumination on ZnO causes the greatest inhibition toward E. coli and S. aureus. Under the UVA excitation, the inhibition of E. coli increased by 18% (ZnO-rod) and 13% (ZnO-plate) while the inhibition of S. aureus increased by 22% (ZnO-rod) and 21% (ZnO-plate). Release of reactive oxygen species were proposed in antibacterial mechanisms, which were aided by surface modification and UVA photoactivation. The reactive oxygen species disrupted the DNA and protein synthesis of the bacterial cell, causing bacteriostatic effects toward E. coli and S. aureus.

Effect of surface modification of zinc oxide on the electrochemical performances of [Ni4Al(OH)10]OH electrode

Surface modification of zinc oxide on the [Ni4Al(OH)10]OH has been performed by a chemical surface precipitation method. Inductively coupled plasma measurements show that the amount of ZnO of prepared samples increases with the increase of initial concentration of Zn2+ in the mother solution. Powder X-ray diffraction measurements and scanning electron microscope images show that the modification of ZnO has little effects on the lattice parameters and the particle sizes of the [Ni4Al(OH)10]OH, but does change the morphology. The charge–discharge cycles results show that the deterioration rate of discharge capacity for the electrode with ZnO is only 4.0 % after 255 cycles, which is lower than that of electrode without ZnO (8.5 %); meanwhile, the maximal numbers of exchanged electrons per nickel atom for the electrodes with ZnO are basically over 1.83, which are higher than that of the electrode without ZnO (1.73), indicating that the modification of ZnO can improve the utilization of active material. In addition, the cyclic voltammogram tests results show that the modification of ZnO not only improves electrochemical cyclic reversibility but also elevates the oxygen evolution potential. Electrochemical impedance spectroscopy measurements show that the modification of ZnO can lower the double layer capacitance and the charge transfer resistance.

The influence of surface modification on the structure and properties of a zinc oxide‐filled poly(ethylene terephthalate)

AbstractHydrophobic zinc oxide (ZnO) nanoparticles were successfully prepared by a one‐step precipitation reaction in an aqueous solution of zinc sulfate and sodium hydroxide with stearic acid as the modifying agent. Poly(ethylene terephthalate) (PET)/ZnO nanocomposites were prepared by further in situ polymerization of purified terephthalic acid, ethylene glycol and the ZnO nanoparticles. The surface modification of ZnO and the microstructure and properties of the nanocomposites were investigated using relative contact angle measurements, Fourier transform infrared spectroscopy, X‐ray diffraction, transmission and scanning electron microscopies, thermogravimetric analysis and differential scanning calorimetry. Measurements of relative contact angle indicated that the surface‐treated ZnO was hydrophobic. Compared to the nanocomposite filled with unmodified ZnO, a significant improvement in thermal stability and crystallinity was observed with the addition of 2 wt% surface‐treated ZnO. The experimental results also suggested that the properties of the nanocomposites were correlated with the dispersion of ZnO in PET and the interfacial interactions between ZnO and PET matrix. © 2012 Society of Chemical Industry

Use of silane coupling agent for surface modification of zinc oxide as inorganic filler and preparation of poly(amide-imide)/zinc oxide nanocomposite containing phenylalanine moieties

A series of novel poly(amide–imide)/ZnO nanocomposites with modified ZnO nanoparticles contents was prepared by ultrasonic irradiation. For this purpose, surface of ZnO nanoparticle was modified with $\boldsymbol\gamma$ -aminopropyltriethoxysilane as a coupling agent. Then the effect of surface modification on dispersion of nanoparticles, thermal stability and UV absorption property of the obtained nanocomposites were investigated. The resulting novel nanocomposites were characterized by several techniques. Field emission scanning electron microscopy and transmission electron microscopy analyses of the nanocomposites were performed in order to study the dispersion of nanofillers in the polymer matrix. According to thermogravimetry analysis results, the addition of ZnO nanoparticles improved thermal stability of the obtained nanocomposites. Since the resulting nanocomposites contain phenylalanine amino acid and ZnO, they are expected to be biocompatible as well as biodegradable.

Excellent UV absorption in spin-coated thin films of oleic acid modified zinc oxide nanorods embedded in Polyvinyl alcohol

The aim of the study is to investigate the optical properties of spin-coated, highly transparent nanocomposite films of oleic acid modified ZnO (Zinc oxide) nanorods embedded in Polyvinyl alcohol (PVA) matrix. Pristine and oleic acid (OA) modified ZnO nanorods have been prepared by wet chemical synthesis and are characterized by X-ray diffraction, FESEM, TEM and FT–IR spectroscopy techniques. The optical properties of ZnO/PVA films are studied using UV–visible absorption and Photoluminescence (PL) spectroscopy. The results show that the optical absorption of the films in the UV region is quite high and more than 95% absorption is observed in films prepared from OA modified ZnO nanorods. The excellent UV absorption at around 300 nm offers prospects of applications of these films as efficient UV filters in this wavelength region. The PL spectrum of pristine ZnO nanorods shows almost white light emission whereas OA modified ZnO nanorods have a more intense peak centered in the blue region. The PL emission of OA modified ZnO/PVA film shows appreciable increase in intensity compared to the film obtained with pristine ZnO. The surface modification of ZnO by the polymer matrix removes defect states within ZnO and facilitates sharp near band edge PL emission at 364 nm.

Surface Modification and Functionalization of Oxide Nanoparticles for Superhydrophobic Applications

Oxide nanoparticles have tremendous technological applications in the present days in diverse fields. In this study, the surface modification and functionalization of hydrophilic silica (SiO2) and zinc oxide (ZnO) nanoparticles were performed to obtain superhydrophobicity. Monodispersive nanoparticles of SiO2were prepared by Stöber process using tetraethoxysilane (Si (OC2H5)4) as a precursor and ammonium hydroxide as a catalyst in a ethanolic solution. The surface modification of the silica nanoparticles were performed using fluoroalkylsilane (FAS-17: C16H19F17O3Si) molecules to obtain fluorinated silica nanoparticles of diameter varying from 50nm to 300nm. On the other hand, surface modification of zinc oxide (ZnO) nanoparticles was performed using stearic acid (C18H36O2) molecules to obtain methylated ZnO nanoparticles. These functionalized nanoparticles were characterized both in the form of powder as well as thin films. The bonding characteristics of FAS-17 molecules with SiO2and stearic acid molecules with ZnO were investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Nanostructured thin films of these functionalized oxide nanoparticles exhibit superhydrophobicity with contact angles over 150° with water roll-off properties. Such functionalized oxides nanoparticles, therefore, can be easily incorporated in coatings and paints for various applications in emerging technologies like biomedical applications, anti-corrosion, anti-icing, drag reduction and energy consumption reduction.