Surface Of Polystyrene Spheres Research Articles

A composite material with controllable electromagnetic characteristics for the terahertz frequency range

In this study, a new method is proposed for producing polymer composites via the adsorption of multiwalled carbon nanotubes (MWCNTs) on the surface of polystyrene spheres (PS) to provide a cellular distribution of MWCNTs in the composite. The method makes it possible to control the cell size down to the submicron level and the conductivity of the composite in a wide range. The effect of the MWCNT concentration on the surface of PS on the structure of the resulting composites and their electrophysical properties are studied in the frequency range of 115 GHz–1.4 THz. The percolation nature of the composite conductivity was established. It was shown that the obtained composite is a regularly chaotic medium, and its regularity scale corresponds to the sizes of the PS. MWCNTs on the PS surface form two subsystems: the first is a pseudo-regular subsystem on the edges of cuboid-like PS, while the second subsystem consists of chaotically scattered MWCNTs with unclosed ends on the faces of PS. The first subsystem belongs to the regular part of the structure and mainly determines the properties of the medium at frequencies above 500 GHz. The second subsystem of nanotubes is characterized by a small electrodynamic scale comparable with the size of one PS cell and determines the effective properties of the composites at frequencies below 500 GHz.

TiO2 hollow spheres with separated Au and RuO2 co-catalysts for efficient photocatalytic water splitting

Abstract Hollow mesoporous TiO2 photocatalysts with dual co-catalysts, located at specific positions, were prepared using Polystyrene (PS) as sacrificial templates. Au nanoparticles (NPs) were in situ loaded on the surface of PS spheres and the resulting nanocomposites were coated with TiO2 shell using sol-gel reaction. The outer surface of core-shell spheres was impregnated with Ru and the subsequent calcination produced hollow anatase spheres with Au and RuO2 dual co-catalysts. The hollow mesoporous spheres of Au@TiO2@RuO2 were proved by various techniques such as TEM, EDX, and SEM images. Photocatalysts were applied for hydrogen generation from water splitting and that with dual co-catalysts showed efficient catalytic activity under simulated solar light. The catalytic activity of photocatalysts with both oxidation and reduction co-catalysts (Au@TiO2@RuO2) showed hydrogen evolution (3165 μmol g−1) almost two times more than that Au@TiO2 and TiO2@RuO2 with single co-catalysts. And the hydrogen evolved is more than three times as compared to TiO2 (935 μmol g−1) without any co-catalyst. Hollow mesoporous morphology with different co-catalysts on inner and outer surfaces is believed to enhance photocatalytic activity which is due to better separation of photo-generated charges.

Co3O4 nanosheet-built hollow spheres containing ultrafine neck-connected grains templated by PS@Co-LDH and their ppb-level gas-sensing performance

Through the hydrothermal approach, cobalt-based layered double hydroxide (Co-LDH) nanosheets were grown on the surfaces of polystyrene spheres (PSs), forming core–shell PS@Co-LDH composites. By calcinating such PS@Co-LDH composites at a low temperature, Co3O4 hollow spheres were then synthesized with a skeleton comprising many ultrathin (5.1 nm) porous nanosheets. Each nanosheet consisted of numerous primary grains approximately 5 nm in size and closely neck-connected with each other, as well as a large number of pores approximately 2–3 nm in size. The use of the Co3O4 nanosheet-built hollow spheres in high-performance gas sensors was found to be advantageous, as revealed by the low detection limit of 4.3 ppb for ethanol vapor and the short detection time of 4 s for dimethyl sulfide. To our knowledge, this detection limit for ethanol vapor is the lowest value in the actual test among p-type metal oxide semiconductor resistance-type gas sensors. Furthermore, a conduction model of the connected hole accumulation layer was proposed to explain the excellent gas sensing performances from Co3O4 nanosheet-built hollow spheres.

Synthesis of Hollow Mesoporous TiO2 Microspheres with Single and Double Au Nanoparticle Layers for Enhanced Visible-Light Photocatalysis.

A facile method was used to prepare hollow mesoporous TiO2 and Au@TiO2 spheres using polystyrene (PS) templates. Au nanoparticles (NPs) were simultaneously synthesized and attached on the surface of PS spheres by reducing AuCl4- ions using sodium citrate which resulted in the uniform deposition of Au NPs. The outer coating of titania via sol-gel produced PS@Au@TiO2 core-shell spheres. Removing the templates from these core-shell spheres through calcination produced hollow mesoporous and crystalline Au@TiO2 spheres with Au NPs inside the TiO2 shell in a single step. Anatase spheres with double Au NPs layers, one inside and another outside of TiO2 shell, were also prepared. Different characterization techniques indicated the hollow mesoporous and crystalline morphology of the prepared spheres with Au NPs. Hollow anatase spheres with Au NPs indicated enhanced harvesting of visible light and therefore demonstrated efficient catalytic activity toward the degradation of organic dyes under the irradiation of visible light as compared to bare TiO2 spheres.

Constructing hierarchical polymer@MoS2 core-shell structures for regulating thermal and fire safety properties of polystyrene nanocomposites

Two dimensional MoS2 acting as reinforcing fillers had attracted intense interests in recent years. However, the homogeneous dispersion of MoS2 nanosheets in polymer matrix and exact interface control were still difficult to achieve due to potent van der Waals forces and surface inactiveness. In this work, hierarchical polystyrene@MoS2 core-shell structures were constructed by combining latex technology and self-assembly of oppositely charged MoS2 nanosheets onto the surface of polystyrene spheres. The formed core-shell structures were characterized by X-ray diffraction, Fourier transform infrared, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy and further employed as reinforcing fillers in a host polystyrene matrix by solvent blending method. It was clearly observed that the construction of polystyrene@MoS2 core-shell structures not only improved the dispersion of MoS2 in the matrix and the interfacial adhesion between MoS2 and polystyrene, but also obviously improved the thermal stability and fire safety of polystyrene. The method proposed here had proved to be an efficient and facile approach to fabricate polymer/MoS2 nanocomposites with good dispersion and markedly improved properties.

PVP-assisted synthesis of raspberry-like composite particles

Composite particles composed of SiO2 nanoparticles and polystyrene (PS) spheres with a raspberry-like structure were successfully synthesized by a PVP-assistant sol–gel method. The as-prepared products were systemically characterized by FT-IR, TGA, SEM and TEM. The characterization results indicated that the amount of polyvinyl pyrrolidone (PVP) and concentration of ammonia solution played key roles in tailoring the structure of the composite particles, including size and surface density of SiO2 nanoparticles on the surface of PS spheres. During the PVP-assisted sol–gel process, the synthesized nano-sized SiO2 particles were favorably deposited on the surface of PS spheres to form hierarchical composite particles. By adjusting the amount of PVP and pH value of reaction system, the typical raspberry-like particles with controllable coverage of SiO2 nanoparticles on PS spheres were obtained. Subsequently, the composite particles with well controllable morphology were modified with OcTMS and orderly deposited on the substrate. The effect of the composite particles with different morphologies on the wetting property was investigated. Finally, superhydrophobic surface was generated and the water contact angle was up to 154°. PS–SiO2 composite particles with hierarchical structure were successfully prepared by a PVP-assisted sol–gel method, which exhibited a superhydrophobic property after surface modification with OcTMS.

Self-assembly of nanoparticles onto the surfaces of polystyrene spheres with a tunable composition and loading

Functional colloidal materials were prepared by design through the self-assembly of nanoparticles (NPs) on the surfaces of polystyrene (PS) spheres with control over NP surface coverage, NP-to-NP spacing, and NP composition. The ability to control and fine tune the coating was extended to the first demonstration of the co-assembly of NPs of dissimilar composition onto the same PS sphere, forming a multi-component coating. A broad range of NP decorated PS (PS@NPs) spheres were prepared with uniform coatings attributed to electrostatic and hydrogen bonding interactions between stabilizing groups on the NPs and the functionalized surfaces of the PS spheres. This versatile two-step method provides more fine control than methods previously demonstrated in the literature. These decorated PS spheres are of interest for a number of applications, such as catalytic reactions where the PS spheres provide a support for the dispersion, stabilization, and recovery of NP catalysts. The catalytic properties of these PS@NPs spheres were assessed by studying the catalytic degradation of azo dyes, an environmental contaminant detrimental to eye health. The PS@NPs spheres were used in multiple, sequential catalytic reactions while largely retaining the NP coating.

Direct Fabrication of Hierarchical Porous Carbonaceous Microparticles by Electron‐Beam Irradiation and Post‐Annealing of Polystyrene Colloidal Crystals

A novel approach to fabricate hierarchical porous carbonaceous microparticles (HPCMs) by electron irradiation of polystyrene (PS) colloidal crystals followed by annealing is presented. Electron irradiation transforms PS spheres into hydrogenated amorphous carbon and post‐annealing further graphitizes the irradiated PS. Colloidal crystals consist of regularly ordered mesopores and electron irradiation and post‐annealing create new micropores on the surfaces of PS spheres. Consequently, PS colloidal crystals were transformed into carbonaceous materials comprising mesopores and micropores. Through mechanically grinding the colloidal crystals, HPCMs are fabricated. Due to comparatively high surface areas and graphitic structures, the HPCMs exhibit moderate adsorption properties for methyl orange in an aqueous solution.

Ultrasensitive multiplexed protein biomarker detection based on electrochemical tag incorporated polystyrene spheres as label

Multiplexed electrochemical immunosensor was developed for ultrasensitive detection of interleukin-6 (IL-6) and interleukin-17 (IL-17) using electrochemical tag incorporated polystyrene sphere (PS) as label. The electrochemical tag contained in the PS, cadmium ion (Cd2+) or ferrocene (Fc), could be effectively detected by square wave voltammetry (SWV) after dissolving the PS with organic solvent to release the electrochemical tags onto electrode surface. With the immobilization of two different antibodies onto the PS surface, respectively, the position and intensity of the current peaks due to the two electrochemical tags could reflect the identity and level of the corresponding protein biomarkers. The significant amount of electrochemical tags incorporated into PS greatly enhanced the detection sensitivity. The proposed immunoassay exhibited high sensitivity and good selectivity for the detection of IL-6 and IL-17. The response current was linear to the logarithm concentrations of IL-6 and IL-17 in the range from 1pg/mL to1ng/mL and 2pg/mL to 1ng/mL, respectively. The detection limits of IL-6 and IL-17 were 0.5 and 1pg/mL (S/N=3). These results suggested that this electrochemical immunosensor would be widely applied for clinical screening of protein biomarkers.

A new strategy for the controlled deposition of gold nanoparticle aggregates on two-dimensional polystyrene arrays and its application in glucose oxidase immobilization

Nano/microstructures play an important role in nanoparticle applications. This paper describes an innovative strategy to fabricate a variety of gold nanoparticle aggregates (AuNPs) on large-scale arrays of up to ∼1cm2 made from polystyrene (PS). A dendritic surfactant, C18N3, has multi-amine head groups that can control the thickness of a double layer adsorbed on the PS sphere surface in a pH-dependent manner. Controlling the pH and immersion time in the C18N3 solution allows the morphology of AuNPs deposited on the PS spheres (PS@AuNP) to be regulated. The influence of nano/microstructures on the activity enhancement of glucose oxidase (GOD) was investigated. The results indicated that well-ordered PS@AuNP arrays performed much better in the specific activity enhancement of GOD compared with free GOD and GOD immobilized on PS arrays. Furthermore, it was observed that the immobilized GOD on 2D PS@AuNP arrays maintained a highly improved operational stability compared to free GOD. The mechanism behind this effect is discussed. For practical applications, prepared PS@AuNP arrays can be used as an effective chip for GOD immobilization and application.

Synthesis, Characterization and Photocatalytic Property of Magnetic Titania Hollow Sphere Composite

The magnetic anatase titania (TiO2) hollow spheres have been fabricated as magnetic photocatalyst by template (polystyrene)-sacrificed method, in which cobalt ferrite and titania was sequentially deposited on the surface of polystyrene spheres via coprecipitation and sol-gel process followed by calcinations. X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) were employed to characterize the products, and the photocatalytic activities were evaluated by photodegradation of methyl orange (MO) under UV illumination. The results indicate that the as-prepared magnetic titania hollow spheres exhibit magnetic property and high photocatalytic activity.

Preparation of Composite Conductive Microspheres Used in Anisotropic Conductive Adhesive Films

Polymer-based conductive adhesive materials have become widely used in many electronic packaging interconnect applications. In this paper, a new kind of polymer-based conductive particle used in anisotropic conductive adhesive films (ACFs) is prepared. The preparation of the single scattered polystyrene spheres with the particle size of 3 microns around and the less than 5% dispersion coefficient is done successfully, and a layer of nickel is coated on the surface of polystyrene spheres using chemical plating method well.

Ampholyte polystyrene spheres self-regulated deposition of noble metal nanoparticles for catalyst applications

The polystyrene (PS) spheres having dual functional groups were synthesized using emulsifier-free emulsion polymerization based on St/potassium persulfate/water system in the presence of V-50 as co-initiator. Fourier transform infrared (FTIR) confirms the presence of the sulfate and the amino groups on the surfaces of PS spheres. Transmission electron microscopy and X-ray photoelectron spectra revealed that the PS spheres were successfully deposited with catalytic palladium (Pd) or gold (Au) nanoparticles (NPs). The reduction of 4-nitroaniline to 4-phenylenediamine used as a model reaction was performed for catalysis studies and examined by ultraviolet. It was found that both Au and Pd PS dispersions show high catalytic activity. The Pd PS dispersion of 200 μl with only Pd content of 1.09 wt.% exhibits an excellent catalytic effect superior to the commercial Pd/C catalyst, i.e., less than 35 s taken for the completion of the reduction of 4-nitroaniline.

Permselective properties of polystyrene opal films at diamond electrode surfaces

The permselective properties of stable opal films formed by polystyrene nanospheres on boron-doped diamond (BDD) electrodes were studied for the first time by means of electrochemical voltammetric and impedance techniques. Films formed from spheres with a diameter above 200 nm are highly porous and have little influence on electrochemical properties. In contrast, porous films formed from 50 nm spheres have a selective influence on the electrochemistry observed, providing an enhancement in the redox peak current for neutral (ferrocenemethanol, dopamine) and positively-charged redox probe mediators (Ru(NH(3))(6)(3+)) and suppressing the current due to a negatively-charged redox species Fe(CN)(6)(4-). This is because the latter is repelled from the film, whereas the former are selectively partitioned within it. Partition coefficients, film permeability and diffusion coefficients of species within the polystyrene opal layer are determined. It is shown that a Langmuir isotherm analysis for adsorption on the polystyrene sphere surface can describe successfully the incorporation of ferrocenemethanol and Ru(NH(3))(6)(3+) within the thin film, with Gibb's free energies (DeltaG(o)) of adsorption in the range of -27 to 28 kJ mol(-1). Apart from influencing the magnitude of the detected electrochemical response, it is also shown the opal film increases the resistance to electrode fouling by the reaction products formed by the oxidation of dopamine. Electrochemical impedance measurements further illustrate the effects of the polystyrene layer.

Preparation of Core/Shell and Hollow Nanostructures of Cerium Oxide by Electrodeposition on a Polystyrene Sphere Template

Core/shell nanostructures of polystyrene (PS)/CeO2 have been prepared on conductive glass substrates by using a novel electrochemical route consisting of (i) the electrophoretic deposition of a PS sphere monolayer on the substrate and (ii) the following potentiostatic electrodeposition of CeO2 on the PS sphere template in Ce(NO3)3 aqueous solutions. The structural morphologies of the deposit changed drastically depending on the Ce(NO3)3 concentration; i.e., spherical and needlelike shells were deposited. The deposit was formed only on the PS sphere surface because of an interaction between cationic cerium species and a sulfate group that was immobilized on the PS sphere surface. The spherical shell layer was assigned as CeO2, and the needlelike shells were composed of Ce(OH)3 needles formed on the CeO2 layer surface, indicating that the deposit species changes from CeO2 to Ce(OH)3 during electrodeposition only in a 1 mM Ce3+ solution. Deposition of Ce(OH)3 would begin when electrogenerated hydrogen peroxide was consumed by decomposition under reductive conditions and could no longer oxidize Ce3+ ions. The corresponding CeO2 hollow shells were obtained by thermal elimination of the PS sphere core and transformation of Ce(OH)3 into CeO2 while keeping their original shapes.

Facile Fabrication of Raspberry-like Composite Nanoparticles and Their Application as Building Blocks for Constructing Superhydrophilic Coatings

Monodisperse raspberry-like polystyrene@silica composite nanoparticles (RCNs) were readily prepared by a single-step sol−gel method, using oxygen plasma-treated monodisperse polystyrene (PS) spheres as cores. The fabricated composite particles have a well-defined structure and a surface morphology of dual-size roughness. The diameter of silica nanoparticles and their coverage degree on the surface of PS spheres could be easily tailored by adjusting the tetraethoxysilane concentration. Subsequently, porous silica hollow sphere coatings were fabricated by depositing the RCNs on polyelectrolyte-modified glass substrates via layer-by-layer assembly followed by calcination. Such porous silica hollow sphere coatings present unique superhydrophilic and antifogging properties even though the coverage degree of porous silica hollow spheres on substrates is only ca. 50%. Therefore, the obtained raspberry-like composite spheres are ideal building blocks for constructing superhydrophilic and superhydrophobic coatings.

Uniform polystyrene microspheres decorated with noble metal nanoparticles formed without using extra reducing agent

Uniform polystyrene (PS) spheres having various sizes from 60 to 1100 nm could be tailored by means of the surfactant-free emulsion polymerization based on styrene/potassium persulfate/water (St/KPS/H 2O) system. These PS spheres can intrinsically exhibit excellent dispersion property owing to their exterior sulfate groups. The Zeta potential measured can originally reach a value of −48 mV for the microspheres with size of 230 nm. By measuring in sodium chloride aqueous solution of 0.07 M, it was found to be greatly enhanced as high as −122 mV. Nano-dot-decorated metal-polystyrene composites could be achieved by a simple wet process in which metal ions such as gold (Au), silver (Ag) and palladium (Pd) were successfully performed metal deposition without any extra reducing agent. We found that the particle sizes of the metal dots deposited onto the surfaces of PS spheres are ranged from 5 to 10 nm. Images of high-resolution transmission electron microscopy and electron diffraction pattern having lattice constant of 2.35 Å revealed that the microstructure of gold (Au) particles anchored onto PS spheres could be fcc nanostructure.

In situ synthesis of sulfide-coated polystyrene composites for the fabrication of photonic crystals

Sulfide (CdS, ZnS, and SnS 2)-coated polystyrene (PS) nanocomposites with a diameter of about 160 nm were synthesized by an in situ synthesis method. The PS spheres adsorbed polyelectrolytes, which were coordinated with Cd 2+ and Zn 2+ reacted with sulfions released through the hydrolysis of thioacetamide in an aqueous bath. As to the SnS 2-coated PS composite, we introduced a deposition method in which a thin layer of SnS 2 was deposited on the surface of PS spheres. The PS spheres assembled on the patterned substrate of porous aluminum oxide (PAO) were more regular than those on the nonpatterned microslide, so the PS spheres coated with CdS and ZnS composites were assembled into ordered arrays on the PAO substrate, respectively. And the obtained λ max of CdS-coated PS colloid crystal array red-shifted 262 nm compared with that of the pure PS colloid crystal array. All the particles and colloid crystal arrays were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Energy-dispersive X-ray (EDX) was undertaken to determine the elements Cd, S, and Sn.

Multi-layered adsorption of 3Y–ZrO 2 nanoparticles on polystyrene microsphere

Multi-layered adsorption of 3Y–ZrO 2 nanoparticles on polystyrene (PS) microsphere using layer-by-layer (LBL) assembly technique was investigated. By employing sodium poly (acrylic acid) (PAANa) and polyethylenimine (PEI) to modify the zeta potential of the powders, the heterocoagulation takes place between the coating powders and microspheres substrate and the zirconia coating on the surface of polystyrene spheres was successfully formed. Dense, uniform multi-layered zirconia can be obtained on the surface of polystyrene spheres and the thickness of zirconia coating increased by repeating the coating process. The diameter of the spheres expands to 1.5 μm after the first coating and 1.65 μm after the third coating comparing with the original polystyrene spheres with diameter of 1.4 μm.

Coating Noble Metal Nanocrystals (Ag, Au, Pd, and Pt) on Polystyrene Spheres via Ultrasound Irradiation

The method of ultrasound irradiation is used for anchoring metallic nanocrystals (Ag, Au, Pd, and Pt) onto the surface of polystyrene spheres. In former studies, almost all the sonochemically prepared, coated metallic nanomaterials were formed as amorphous nanoparticles (Pol, V. G.; et al. Langmuir 2002, 18, 3352; Pol, V. G.; et al. Chem. Mater. 2003, 15, 1111; Zhong, Z. Y.; et al. Chem. Mater. 1999, 11 (9), 2350; Pol, V. G.; et al. Chem. Mater. 2003, 15, 1378), which were coated on various substrates (silica spheres, carbon spherules, titania, and alumina). On the other hand, the noble metal nanoparticles deposited on polystyrene spheres via ultrasound irradiation yielded nanocrystalline Ag, Au, Pd, and Pt particles on the surface of polystyrene as as-synthesized materials. The sonochemical mechanism is proposed based on chemical interactions between the particles.