Monodisperse Polystyrene Microspheres Research Articles

The influence of water on size of the monodisperse polystyrene microspheres prepared by dispersion polymerization

AbstractPolystyrene microspheres with uniform sizes have a wide range of applications in biomedical engineering. However, detailed and systematic investigations on the influence of water content on alcohol/water systems are relatively scarce. In this study, the impact of trace water content on microsphere size was comprehensively examined, and a systematic exploration of the varying effects of different hydration levels on particle nucleation and growth mechanisms was conducted. When the water content increased from 0.1% to 0.4%, the microsphere diameter rapidly decreases from 3.6 to 2.71 μm. Correspondingly, the molecular weight increased from 29,797 to 69,186. However, within the water content range of 0.5%–14.5%, alterations in water content induced only slight variations in the microsphere diameter. The microsphere size, molecular weight, conversion rate, and reaction rate were compared in two stages. It was observed that the diminishing influence of water on the system was due to the changes in the main polymerization sites. Subsequently, the addition of water content up to 33.5% revealed an exponential decrease in the microsphere size with increasing water content in ethanol. This pattern was also observed in methanol and isopropanol, demonstrating its universality and predictability, making it applicable for precise prediction of microsphere size in different solvents.

Monodisperse Fluorescent Polystyrene Microspheres for Staphylococcus aureus Aerosol Simulation.

Staphylococcus aureus (SA) is one of the most common causes of hospital-acquired infections and foodborne illnesses and is commonly found in nature in air, dust, and water. The spread and transmission of SA aerosols in the air has the potential to cause epidemic transmission among humans and between humans and animals. To effectively provide the timely warning of SA aerosols in the atmosphere, the identification and detection of SA aerosol concentrations are required. Due to their homogeneous physicochemical properties, highly monodisperse submicron polystyrene (PS) microspheres can be used as one of the simulants of SA aerosols. In this study, 800 nm monodisperse fluorescent PS (f-PS) microspheres with fluorescence spectra and particle size distribution similar to those of SA were prepared. The 800 nm monodisperse f-PS microspheres had a fluorescence characteristic peak at 465 nm; in aerosols, 800 nm monodisperse f-PS microspheres with a similar particle size distribution to that of SA were further verified, mainly in the range of 500 nm-1000 nm; finally, it was found that the f-PS microspheres still possessed similar fluorescence characteristics after 180 days. The f-PS microspheres prepared in this study are very close to SA in terms of particle size and fluorescence properties, providing a new idea for aerosol analogs of SA.

New Method for Measuring the Scattering Phase Function of Micron/Nano Particles

The scattering phase function is crucial to analyze the light transport in the micron/nano particle suspensions. A new method including a liquid–particle system and reference system is proposed to measure the scattering phase function of the liquid–particle suspensions. In this method, a reference system of a standard particle is used to obtain the correction factor to compensate for the influence of the cuvette. Experimental validation was conducted for monodisperse silicon dioxide microspheres and monodisperse polystyrene microspheres. By considering the influence of the cuvette, both theoretical and experimental analyses prove that the proposed method can achieve a good result in the measurement of the scattering phase function of liquid–particle suspensions for particles with unknown size parameters and optical constants, especially when the size parameter of the particle is larger than 10. The correction factors of scattering light distribution of silicon dioxide microsphere suspensions with various mean particle sizes were obtained and analyzed. This method provides an alternative and simple way of measuring the scattering phase function of micron/nano particle suspensions.

Ordered Macro-Microporous Single Crystals of Covalent Organic Frameworks with Efficient Sorption of Iodine.

Fashioning microporous covalent organic frameworks (COFs) into single crystals with ordered macropores allows for an effective reduction of the mass transfer resistance and the maximum preservation of their intrinsic properties but remains unexplored. Here, we report the first synthesis of three-dimensional (3D) ordered macroporous single crystals of the imine-linked 3D microporous COFs (COF-300 and COF-303) via a template-assisted modulated strategy. In this strategy, COFs crystallized within the sacrificial colloidal crystal template, assembled from monodisperse polystyrene microspheres, and underwent an aniline-modulated amorphous-to-crystalline transformation to form large single crystals with 3D interconnected macropores. The effects of the introduced macroporous structure on the sorption performances of COF-300 single crystals were further probed by iodine. Our results indicate that iodine adsorption occurred in micropores of COF-300 but not in the introduced macropores. Accordingly, the iodine adsorption capacity of COF single crystals was governed by their micropore accessibility. The relatively long diffusion path in the non-macroporous COF-300 single crystals resulted in a limited micropore accessibility (48.4%) and thus a low capacity in iodine adsorption (1.48 g·g-1). The introduction of 3D ordered macropores can greatly shorten the microporous diffusion path in COF-300 single crystals and thus render all their micropores fully accessible in iodine adsorption with a capacity (3.15 g·g-1) that coincides well with the theoretical one.

The preparation of novel AIE fluorescent microspheres by dispersion polymerization

ABSTRACT An approach to prepare monodisperse polystyrene microspheres with aggregation-induced emission (AIE) characteristics has been developed which shows promising applications in fluorescence-encoding. The micron-sized, monodisperse polystyrene microspheres with AIE molecules were perfectly synthesized by two-stage dispersion polymerization. Fluorescent AIE monomer was synthesized by Suzuki reaction, confirmed by nuclear magnetic resonance (NMR). These AIE fluorogens (AIEgens) exhibited unique properties such as bright green emission in solid state and increased emission in tetrahydrofuran (THF) solution with the increase of water content. The influence of the AIE molecules concentration to microspheres synthesis was well investigated. The reaction conditions were optimized to obtain the functional polystyrene microspheres with a size distribution around 3%. The novel microspheres were characterized by scanning electron microscopy (SEM), confocal fluorescence microscope and flow cytometry. According to these results, two-stage dispersion polymerization was proved to be an efficient pathway for the preparation of AIE fluorescent and functionalized microspheres, which could be used in many biomedical industries.

Construction of Rainbow-like Structural Color Coatings on Wood Surfaces Based on Polystyrene Microspheres

Polystyrene (PSt) microspheres were used to construct rainbow-like, seven-colored structural color coatings on wood surfaces by analyzing how the amount of emulsifier SDBS and emulsion polymerization temperature affected the particle size and monodispersity of the microspheres. The influence of both the amount of self-assembled emulsion coating used and the temperature on the reflected spectrum and the color of the coatings was investigated. It was found that the most monodisperse PSt microspheres were obtained when using 175 mg SDBS and a reaction temperature of 70 °C. By adjusting these two factors, we regulated the particle size of the PSt microspheres. When PSt microspheres were self-assembled on a wood surface to form a structural color coating, the best optical effect was obtained with 40.8 × 10−3 mL/cm2 emulsion amount and 50 °C ambient temperature. Finally, by changing the SDBS amount and reaction temperature, microspheres with different particle sizes and good monodispersity were prepared. The structural color was used to form patterned decorations on the wood surface, providing a technical basis for forming other structural color coatings on wood surfaces.

Physiological response of ectomycorrhizal fungi (Lactarius delicious) to microplastics stress

<p>The pollution and toxicological effects of microplastics in soil have gradually attracted widespread attention, but studies on the ecological effects of microplastics on soil microorganisms and their mechanisms are still very scarce. To explore the physiological response of ectomycorrhizal fungi (Lactarius delicious, Ld) to microplastic stress, Ld was used as the test strain, and 80 nm and 4 μm monodisperse polystyrene microspheres (PS-MPs) were selected. The solid plate method and the liquid culture method were used to study the effect of PS-MPs with two particle sizes on the growth, nutrient content, reactive oxygen species (ROS) production, organic acid secretion and other indicators of the strain Ld. The results showed that with increasing PS-MPs concentration, the biomass of strain Ld decreased gradually. When the strain Ld was exposed to high concentrations of PS-MPs (200-300 mg L-1), PS-MPs with particle size of 4 μm showed stronger inhibition of biomass than PS-MPs with particle size of 80 nm. After exposure to the PS-MPs environment of two sizes, the concentration of PS-MPs increased (0-300 mg L-1), and the contents of phosphorus (P), potassium (K), H2O2 and superoxide anion radical (O2·-) in Ld mycelia increased significantly (p < 0.05). This showed that the antioxidant substances in Ld could not remove excess ROS, but could reduce the stress of microplastics by increasing the absorption of P and K from the environment, which was beneficial to its own metabolic activities. In addition, the strain Ld could secrete oxalic acid, acetic acid and succinic acid into the culture medium, which the amount of oxalic acid secreted was the highest. We speculated that strain Ld responded to the stress of microplastics by secreting a large amount of organic acids. Therefore, the mechanism of the influence of microplastics on ectomycorrhizal fungi may involve oxidative stress, and the mycelia responded to the toxicity of microplastics by secreting more organic acids and increasing the absorption of P and K. The results of this study will provide a scientific basis for the study of the acute toxicity of microplastics to ectomycorrhizal fungi.</p>

Preparation of three-dimensional ordered macroporous Ag/LaFeO3 and heterogeneous photo-Fenton degradation of penicillin G potassium

ABSTRACT 3DOMLaFeO3 was prepared by template method combined with sol-gel method using monodisperse polystyrene (PS) microspheres as template, and Ag/3DOMLaFeO3 perovskite catalyst was prepared by impregnation method combined with sodium borohydride reduction method. The catalysts were characterised by means of TG, XRD, SEM, BET, XPS, UV-vis DRS, etc. The photo-Fenton catalytic performance, stability and catalytic reaction mechanism of Ag/3DOMLaFeO3 were studied with penicillin G potassium (PEN G) as the model pollutant. The results indicated that the as-prepared Ag/3DOMLaFeO3 exhibited a three-dimensional ordered macroporous (3DOM) structure, and the light capture and mass transfer were enhanced through abundant pores and large specific surface area. Based on the surface plasmon resonance effect (SPR), Ag loading enhanced the absorption of the material in the visible light region, and inhibited the recombination of photogenerated carriers, which improved the photocatalytic performance of 3DOMLaFeO3 under visible light. Under the conditions of hydrogen peroxide dosage of 1.5 mL·L−1, initial pH of 5, PEN G initial concentration of 100 mg·L−1, catalyst dosage of 300 mg·L−1, xenon lamp irradiation, the degration ratio of PEN G and the removal rate of TOC reached 99.99% and 85.45% within 120 min, respectively. In addition, it had a wide range of pH application, excellent stability and practical application value. The quenching experiment and ESR test showed that ·OH and ·O2 − were the reasons for high catalytic degradation. The least square method was used to fit the experimental data, and the results displayed that the degradation of PEN G was approximately in line with the first-order kinetic reaction.

Preparation and application of monodisperse, highly cross-linked, and porous polystyrene microspheres for dye removal

The porous materials as adsorbents play an important role in dye removal. In this paper, monodisperse, highly cross-linked porous microspheres with a specific surface area of 255.83 m²/g and average pore size of 8.5 nm were synthesized by seed swollen emulsion polymerization. The sulfonation reactions of porous microspheres were carried out to improve the hydrophilic performance and electronegativity of the microsphere surface. Cationic methylene blue (MB) and anionic methyl orange (MO) were employed as simulated dye wastewater to investigate the adsorption kinetics of porous microspheres. The experimental results demonstrate that porous sulfonate microspheres possess selective adsorption for MB due to electrostatic interaction between the negative charges on the surface of microspheres and the positive charges of MB molecules. Porous microspheres exhibit an adsorption capacity of 313.125 mg/g after 2 h. The adsorption kinetics of MB dyes in porous microspheres follow a pseudo-second-order model.

The improved photocatalytic performance of the gully-like CdS-APS@TiO2-ZrO2 composite by constructing Z-scheme heterojunction

Using monodisperse polystyrene (PS) microspheres as the template, a series of CdS-APS@TiO2-ZrO2 composites (APS = 3-aminopropyltriethoxysilane) with gully-like morphology were prepared. Results from various characterisation methods indicated that grafting CdS did not change the original gully-like structure of the TiO2-ZrO2 composite. However, this unique gully-like structure could provide more channels for the transfer of electrons and inhibit the recombination of photogenerated carriers. Compared with pure TiO2 and ZrO2, the CdS-APS@TiO2-ZrO2 composite had a red-shifted band edge absorption due to the improvement of its physical and chemical properties. The results of photoluminescence spectroscopy and the electrochemical impedance showed that the lifetime of photogenerated charge carriers in the CdS-APS@TiO2-ZrO2 composite was prolonged, which inhibited the recombination of photogenerated electron–hole pairs. The results of multi-mode photocatalytic experiments revealed that CdS-APS@TiO2-ZrO2 composite exhibited the best photocatalytic activity. Moreover, the hydrogen evolution amount was 90 times P25, which has good cycling stability. Finally, a direct dual Z-scheme photocatalytic mechanism was proposed by investigating the active species in the photocatalytic reaction of the CdS-APS@TiO2-ZrO2 composite.

Facile Fabrication of Amorphous Colloidal Array Patterns with Good Mechanical Stability via an Infiltration-Driven Mayer Rod Coating Method

In this study, cationic monodisperse polystyrene (PS) microspheres and polybutyl acrylate (PBA) nanoparticles were synthesized and used in combination to fabricate various steady amorphous colloidal array (ACA) patterns via an infiltration-driven Mayer rod coating method. During the rapid assembly process, PBA nanoparticles were embedded in PS microsphere voids to lock the colloidal array, thereby promoting its mechanical stability. Meanwhile, the fabricated ACA patterns could still exhibit bright angle-independent structural color when moderate PBA nanoparticles introduced. In summary, this study provides a convenient and fast method to fabricate steady ACA patterns, which is a promising potential substitute for traditional ink printing.

Controllable synthesis of polystyrene microspheres used as template and in‐situ carbon source for Li 2 MnSiO 4 cathode material to boost lithium‐ion batteries performance

Polyanion-type Li2MnSiO4 is considered to be a potential lithium storage material due to its high theoretical capacity, low cost, nontoxicity, and good thermal stability. Unfortunately, pure Li2MnSiO4 has poor conductivity and diffusion rate of Li+, which hinders its wide application in energy storage. In this study, Li2MnSiO4 with inverse opal structure is synthesized by simple sol–gel method, and monodisperse polystyrene microspheres (PS) with uniform and controllable size are prepared by soap-free emulsion. Additionally, Li2MnSiO4 material with a large specific surface area and mesoporous structure is synthesized by using PS as a template. Specifically, after adding 4 wt% of the PS template, the initial discharge specific capacity of the synthesized Li2MnSiO4 material is 109.9 mAh·g−1 at 0.1 C. Compared with pure Li2MnSiO4, the electrochemical performance of the material synthesized by this process has been significantly improved, which is attributed to the mesoporous structure and large specific surface area that improve the conductivity. Hence, the Li2MnSiO4 cathode material synthesized with PS as a template is expected to become an advanced positive material in lithium energy storage.

Properties of Kevlar fabric composites reinforced by STF composed of monodisperse polystyrene microspheres

Shear thickening fluid (STF) composed of monodisperse polystyrene microspheres (m-PS-m) was prepared, and soft armor composites was constructed with Kevlar fabric reinforced by this STF in this work. Both the knife and the spike stab resistance performance of this soft composite are investigated and discovered to improve significantly over the neat Kevlar fabric (NKF), and the puncture resistance of the spike is dramatically superior to the cut resistance of the knife. 8 layers of STF-impregnated Kevlar fabric (STKF) will not be punctured under the highest impact energy while 10 sheets of NKF is impaled easily even under the lowest striking energy in experiments. The tensile strength of this soft composite is increased by more than 55% compared to NKF. The highest pull-out force for single yarn in STKF is nearly 6 times that of NKF. The highest pull-out force of single yarn and tensile strength for STKF are greatly improved to make it meet more requirements of different situations. More importantly, the excellent stab resistant and burst strength performance of STKF indicate that it has broad application prospects in the field of soft body armor.

Scalable synthesis of monodisperse and recyclable sulphonated polystyrene microspheres for sustainable elimination of heavy metals in wastewater

ABSTRACT Herein, we demonstrate a scalable method for fabricating monodisperse sulphonated polystyrene (SPS) microspheres with abundant sulphonic acid groups and excellent heavy metal removal ability. A comprehensive characterization through SEM, EDS, FT-IR, TG, XRD and XPS confirmed the formation of the SPS microspheres. Take advantage of the abundant sulphonic acid groups on the surface of microspheres, as well as the superior monodisperse properties, adsorption ability of SPS microspheres both in quantity and speed have been enhanced. The adsorption equilibrium obeyed the Langmuir isotherm model with the theoretical maximum capacities of 49.16, 15.38 and 13.89 mg·g−1 for Pb2+, Zn2+ and Cu2+, respectively (30°C, pH = 3.5). Besides, the adsorption equilibriums of Pb2+ onto SPS microspheres can be achieved within only 1 min and the adsorption kinetics can be fitted by a pseudo-second-order kinetics model. More importantly, because of the micron structure of the SPS microspheres, it could overcome the excessive hydrophilia brought by rich sulphonic acid groups and thereby easily separated, which maintain a good recyclable capacity after five regeneration cycles. With the excellent adsorption ability and reusability, SPS microspheres can efficiently handle the polluted water in a convenience and rapid process, which satisfies the sustainable pollution treatment in heavy metals elimination.

Preparation of monodisperse polystyrene microspheres with different functional groups using soap-free emulsion polymerization

Monodisperse polystyrene microspheres with different functional groups have important applications in both the medical and analytical fields. In this study, we prepared monodisperse microspheres with sulfonic acid or carboxyl groups using soap-free emulsion polymerization (SFEP) with potassium persulfate as the initiator. A series of monodisperse polystyrene microspheres with sizes between 100 and 500 nm were successfully prepared by copolymerizing different types of ionic monomers at different concentrations. The microspheres were characterized by using dynamic light scattering (DLS), Zeta potential measurements (ZP), FT-IR spectroscopy, and transmission electron microscopy (TEM). The mechanism of the particle nucleation and growth were studied by combining the changes in particle size and the number of particles. The results showed that the addition of hydrophilic comonomers like sodium p-styrene sulfonate, acrylic acid, and methacrylic acid significantly improved the stability of the polystyrene microspheres and promoted particle nucleation, resulting in less particle aggregation and microspheres with smaller sizes.

Monodisperse polystyrene microspheres containing quaternary ammonium salt groups by two-stage dispersion polymerization: effect of reaction parameters on particle size and size distribution

A facile approach to prepare monodisperse polystyrene (PS) particles containing quaternary ammonium salts with long alkyl chain was reported. The PS particles containing quaternary ammonium salts are prepared by two-stage dispersion polymerization in ethanol/water (80/20 w/w) mixture with polyvinylpyrrolidone (PVP) as a steric stabilizer and fatty alcohol polyoxyethylene ether (AEO-9) as a co-stabilizer. Polymerizations are conducted using N′-dimethyl-N-n-dodecyl-N-2-methacryloyloxyethylammonium bromide (QDMDB) as a comonomer added in the second stage. We identify reaction conditions where one can obtain the functional polystyrene microspheres with a size distribution less than 3%. The influence of the initiator concentration, the styrene monomer concentration, the stabilizer concentration, and QDMDB comonomer concentration on the average particle size and the efficient of variation are investigated comprehensively. The novel particles are examined using scanning electron microscopy (SEM), gel permeation chromatography (GPC), zeta potential, and nuclear magnetic resonance (1H NMR). QDMDB comonomer not only functionalized the polystyrene particles but also proved to be effective in controlling the particle size and size distribution. According to these results, we show that two-stage dispersion polymerization is an effective pathway for the structure design of the functional microspheres.

Poly(2,5-dimethoxyaniline) coated polystyrene microspheres and their electrorheological characteristics

We synthesized core–shell type spherical semiconducting poly(2,5-dimethoxyaniline) (PDMA)-coated polystyrene (PS) (PS/PDMA) particles with uniform size and investigated their electrorheological (ER) response. Using monodisperse PS microspheres initially synthesized by dispersion polymerization, 2,5-dimethoxyaniline monomer was pre-adsorbed onto the PS surface via π–π stacking interaction, and then PDMA was synthesized by oxidative polymerization. Morphology of the synthesized PS/PDMA particles was observed by both scanning electron microscopy and transmission electron microscopy, while their chemical compound was confirmed by Fourier transform infrared spectroscopy. The PS/PDMA microspheres were suspended in silicone oil and their ER properties were studied using a rotational rheometer from both steady shear and oscillatory test modes. Flow curves were observed to be fitted well with the Bingham fluid equation, while all three differently measured yield stresses showed similar electric field dependence. Furthermore, dielectric analysis confirmed the degree of relaxation time and polarizability related to the ER behaviors of the PS/PDMA particle-based ER fluid. PS/PDMA particles with several advantages such as easy conductivity control through a doping and a de-doping process, their spherical shape and controllable size are expected to be of great help in their multiple applications in both ER fluids and colloidal science.

Determination of refractive index, size, and solid content of monodisperse polystyrene microsphere suspensions for the characterization of optical phantoms.

Monodisperse polystyrene microspheres are often utilized in optical phantoms since optical properties such as the scattering coefficient and the scattering phase function can be calculated using the Mie theory. However, the calculated values depend on the inherent physical parameters of the microspheres which include the size, refractive index, and solid content. These parameters are often provided only approximately or can be affected by long shelf times. We propose a simple method to obtain the values of these parameters by measuring the collimated transmission of polystyrene microsphere suspensions from which the wavelength-dependent scattering coefficient can be calculated using the Beer-Lambert law. Since a wavelength-dependent scattering coefficient of a single suspension is insufficient to uniquely derive the size, refractive index and solid content by the Mie theory, the crucial and novel step involves suspending the polystyrene microspheres in aqueous sucrose solutions with different sucrose concentrations that modulates the refractive index of the medium and yields several wavelength-dependent scattering coefficients. With the proposed method, we are able to obtain the refractive index within 0.2% in the wavelength range from 500 to 800 nm, the microsphere size to approximately 15 nm and solid content within 2% of their respective reference values.

Oxidative Desulfurization of Fuel Oil at Room Temperature Catalyzed by Ordered Meso-macroporous HPW/SiO2

A serial of ordered meso-macroporous phosphotungstic acid (HPW) supported on SiO2 nanocomposites were successfully prepared by a homogeneous precipitation method, using monodispersed polystyrene (PS) microspheres and cationic surfactant as structure directing agent. These nanocomposites were used as catalysts for oxidative desulfurization (ODS) of model fuel. The materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption isothrem, X-ray diffraction (XRD), and Fourier transform infrared spectra (FTIR). The characterization results suggested that the as-prepared material possessed ordered meso-macroporous architectures with Keggin type phosphotungstic acid dispersed homogeneously in SiO2 matrix. Under the selected reaction conditions, dibenzothiophene (DBT) in model fuel can be removed within 2 h at room temperature (30 °C). In addition, only 1.2% of efficiency lose than the fresh catalyst even after 5 cycles.

Preparation of surface-modified monodisperse polystyrene microspheres with cationic functional comonomer

A two-stage synthesis of surface-functionalized monodisperse polystyrene (PS) microspheres in ethanol/water medium by introducing methacryloyloxyethyl dodecyl dimethyl ammonium bromide (QDMDB) to dispersion polymerization of styrene is reported. Polyvinylpyrrolidone (PVP) and fatty alcohol polyoxyethylene ether (AEO-9) are used as dispersion stabilizers. The novel microspheres are characterized by FT-IR, SEM, GPC, TGA, water contact angle (WCA), etc. The dispersion polymerization goes through successfully with the solid content up to 58.75%, in which the water content in the medium is 20%. The water content in the medium has a certain effect on the particle size and molecular weight of microspheres. Under the experimental conditions, the average diameters of the obtained microspheres are approximately 550–1200 nm with the number average molecular weight of up to 5.8 × 105. The introduction of QDMDB improves the wettability and thermal stability of the poly(St-co-QDMDB) microspheres. A mechanism of dispersion copolymerization based on XPS and 1H NMR is proposed.