Porous Polystyrene Microspheres Research Articles

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.

Rapid and efficient oil removal from O/W emulsions by hydrophobic porous polystyrene microspheres embedded with hydrophilic surface micro-regions

Inspired by Namib Desert beetle’s back which is patterned with different wetting properties, hydrophobic porous polystyrene microspheres embedded with hydrophilic surface micro-regions (HPHs) were designed and fabricated by the radical copolymerization in the W1/O/W2 double Pickering emulsions with high internal water phase. The synergistic effect of the hydrophobic surface and the hydrophilic surface micro-regions results in HPHs exhibiting superior performances for separating both surfactant-free and surfactant-stabilized O/W emulsions. After 60 s hand-shaking, the oil was absorbed and stored within HPHs which could be separated from the water using a 600-mesh sieve, and the TOC values of purified water could be reduced to 2.06 ± 0.06–67.38 ± 2.02 ppm when the initial oil content was 1 vol%. Meanwhile, HPHs could be recovered and reused through a simple treatment. The excellent oil removal efficiency was kept even after 50 cycles. High oil removal efficiency, general applicability, easy operation and excellent recyclability endow HPHs with great potential for practical applications. And this work provides a facile and general way to prepare porous polymer microspheres with wettability contrast surfaces.

Continuous-flow microfluidic device for synthesis of cationic porous polystyrene microspheres as sorbents of p-xylene from physiological saline

New developments in microfabrication techniques have enabled the fabrication of very efficient emulsification microstructured devices which along with capillaries of small dimensions allow emulsifying a fluid in another immiscible fluid. Droplet-based microfluidics is a versatile tool for widespread applications due to the following advantages: production of monodisperse droplets, high surface-area-to-volume ratio, and independent control of each droplet. The main goal of this work was to design cationic polystyrene microspheres with the developed surface structure using microfluidic technology. We investigated the influence of monomer phase composition on the size, polydispersity index (PDI), the size distribution and surface structure the resulting microspheres. Polymer microspheres with different surface structure are thus obtained as proven by extensive morphological characterizations using electronic and optical microscopies. Moreover, the structure of crosslinked microspheres was investigated by FTIR spectroscopy. Besides morphology, microspheres with various compositions were synthesized and their potential application highlighted: microspheres with grafted chains of polymer stabilizer (PVP) in surface layer have great potential for effective sorption of p-xylene from physiological saline.

Synthesis of highly porous polymer microspheres with interconnected open pores for catalytic microreactors

• A synthetic method for producing highly porous PS microspheres was developed. • The porous PS microspheres had interconnective open pores. • PS seed particles were dispersed in different types of oil-in-water emulsions. • Catalytic microreactors were fabricated by using the porous PS microspheres. • The microreactors exhibited extremely high catalytic activity. Porous polymer microspheres with interconnective open pores have attracted significant interest, owing to their unique properties as compared to those of traditional microspheres. However, developing a facile synthetic method to produce these unique particles remains a challenge. Herein, a method is proposed to produce highly porous polystyrene (PS) microspheres with interconnective open pores and a uniform size distribution, which were prepared by simply dispersing PS seed particles in an oil-in-water emulsion system. The morphological evolutions of the PS microspheres exposed to different types of oil-in-water emulsions were systematically investigated, and the relationship between the colloidal stability of the emulsions and the final structure of the PS microspheres was studied. Based on these results, the best oil-in-water system for synthesizing highly porous PS microspheres with interconnected open pores was found. The proposed synthetic method was demonstrated to offer significant advantages over previously developed techniques; it was simple, fast, and easy to process, and did not require special additives such as surfactants, complex techniques, etching processes to generate pores, and sophisticated equipment. Catalytic microreactors were fabricated by synthesizing mono- and bimetallic nanocrystals on the surface of the porous microspheres via in situ chemical reduction. When the microreactors were used as a heterogenous catalyst for the 4-nitrophenol (4-NP) reduction reaction by sodium borohydride (NaBH 4 ), they exhibited extremely high catalytic activity and excellent recyclability. These results demonstrated that the highly porous microspheres have very high porosity, huge surface area per unit volume, and good chemical stability, indicating their great potentials as a supporting material for practical applications in catalysis.

Porous polystyrene nanoparticles as nanocontainers of inhibitors for corrosion protection of low-alloy steel

PurposeThis paper aims to investigate effect of porous polystyrene microspheres encapsulated inhibitor on the protection performance of epoxy resin coating.Design/methodology/approachPorous polystyrene (PS) microspheres were synthesized by soap-free emulsion polymerization. The morphology of microspheres was observed by scanning electron microscopy and transmission electron microscopy. Corrosion inhibitor benzotriazole was encapsulated into porous PS microspheres. The protection performance of epoxy resin coating with different contents of PS microspheres was tested by polarization curve.FindingsThe findings of electrochemical impedance spectroscopy and scanning vibrating electrode technique showed that addition of corrosion inhibitor to porous PS microspheres further improved the protection performance of the coatings.Practical implicationsPorous PS microspheres could be used as nanocontainer to encapsulate corrosion inhibitor.Originality/valueAddition of porous PS microspheres with corrosion inhibitor improved the protection performance of the coatings.

Study on High Activity Monodispersed Sulfonated Porous Polystyrene Microspheres for Preparation of Biodiesel

Study on High Activity Monodispersed Sulfonated Porous Polystyrene Microspheres for Preparation of Biodiesel

Differentiation of suspended particles by polarized light scattering at 120°.

Probing suspended particles in seawater, such as microalgae, microplastics and silts, is very important for environmental monitoring and ecological research. We propose a method based on polarized light scattering to differentiate different suspended particles massively and rapidly. The optical path follows a similar design of a commonly used marine instrument, BB9, which records backscattering of non-polarized light at 120°. In addition, polarization elements are added to the incident and scattering path for taking polarization measurements. Experiments with polystyrene microspheres, porous polystyrene microspheres, silicon dioxide microspheres, and different marine microalgae show that by carefully choosing the incident polarization state and analyzing the polarization features of the scattered light at 120°, these particles can be effectively differentiated. Simulations based on the Mie scattering theory and discrete dipole approximation (DDA) have also been conducted for particles of different sizes, shapes and refractive indices, which help to understand the relationship between the polarization features and the physical properties of the particles. The laboratory system may serve as a prove-of-concept prototype of new instrumentations for applications on board or even with submersibles.

Control of the Porous Structure of Polystyrene Particles Obtained by Nonsolvent Induced Phase Separation.

Porous polystyrene microspheres were produced by a process of nonsolvent induced phase separation (NIPS) from ternary polymer-solvent-nonsolvent (polystyrene-toluene-ethanol) systems and characterized by scanning electron microscopy (SEM) and small-angle X-ray scattering (SAXS) techniques. This study provides evidence for a link between the structural morphology of the porous polystyrene particles and the polystyrene concentration in the initial solutions. A reciprocal relationship between pore diameter and polymer concentration was observed for the systems with the polymer amount below the critical chain overlap concentration, C*. Above C*, this relationship breaks down. The reciprocal relationship between porosity and polymer concentration can be used to facilitate the fine control of the void size. We demonstrate that the observed reciprocal relationship between pore diameter and polymer concentration correlates well with the relative amount of nonsolvent present in the system at the onset of the phase separation process. The pore size can be reduced and, consequently, the pore surface area can be increased either by reducing the polymer concentration in the initial solution or by decreasing the polymer molecular weight in the sample composition.

Preparation and Properties of Photochromic Microspheres

Monodisperse porous polystyrene microspheres were prepared with the mixed solution of ethanol and water as dispersion medium and poly (vinylpyrrolidone) was used as dispersant. The even size of microspheres prepared at optimal process was about 1μm. Photochromic microspheres were obtained using polystyrene microspheres to absorb the photochromic materials. The effect of dispersion medium on the microspheres morphology was investigated. The adsorption parameters affecting microspheres adsorption quantity, such as the concentration of spiropyran solution and adsorption temperature, were studied in detail. Furthermore, photochromic properties of the microspheres were analyzed and PVA as coating was used to increase the fatigue resistance of photochromic microcapsules. The photochromic microspheres obtained could rapid reversibly change color under UV or sun light at room temperature and common pressure.

Removal of nitro aromatic compounds and sulfite acid from distillate of 2,4,6‐trinitrotoluene red water using modified porous polystyrene microspheres

AbstractTo remove the nitro aromatic compounds (NACs) and SO32− from distillate of 2,4,6‐trinitrotoluene (TNT) red water, the carboxylated and aminated polystyrene (PSt) microspheres were used as adsorbents. GC‐MS and HPLC analysis were used to determine the types and concentrations of NACs before and after adsorption. The carboxylated PSt, which was prepared by modifying PSt with phthlandione (PA), could remove the neutral NACs including 2,6‐dinitrotoluene (2,6‐DNT), 2,4‐dinitrotoluene (2,4‐DNT), 1,3,5‐trinitrobenzene (1,3,5‐TNB), and 2,4,6‐trinitrotoluene (2,4,6‐TNT), with the acid 2,4‐dinitrophenol (2,4‐DNP) and SO32− remained in the distillate. The aminated PSt that was synthesized by activating PSt with chloroacetyl chloride follow by reaction with 1,2‐ethanediamine (EDA) could remove all the NACs and SO32−. The results suggested that EDA‐PSt adsorbed the NACs though multimode interactions, i.e., hydrogen bond and electrostatic attraction. After adsorption using EDA‐PSt, chemical oxygen demand (COD) was reduced from 86.1 to 11.2 mg L−1, and a colorless, transparent, and nontoxic solution with neutral pH value was obtained. Five grams of EDA‐PSt could purify 1600 cm3 of distillate of TNT red water, and the adsorbents could be recycled by elution with methanol to desorb the neutral NACs followed by elution with 0.1 mol L−1 NaOH to wash off 2,4‐DNP and SO32−. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Adsorption of 2,4,6-trinitrotoluene on carboxylated porous polystyrene microspheres

Large-pore-size (150nm) polystyrene (PSt) microspheres were carboxylated with phthalic anhydride (PA) through Friedel–Crafts acetylation to study the adsorption of 2,4,6-trinitrotoluene (TNT) on this material from aqueous solution. The scanning electron microscope (SEM) images and mercury porosimetry measurements (MPM) of the microspheres showed that the pore structure was unchanged during the reaction. High adsorption capacity (11.2mgg−1 of suction-dried adsorbent) and adsorption rate (33.9mgg−1h−1) for TNT were observed during the study. As shown by the adsorption isotherm, the adsorption of TNT on PA–PSt can be described by the Freundlich adsorption equation, indicating heterogeneous adsorption process. On-column adsorption of TNT on PA–PSt and elution indicated that TNT can be completely removed from aqueous solution and condensed into acetone.

Porous polystyrene microspheres having dimpled surface structures prepared within micellar assemblies of amphiphilic silica particles in water

Production of porous polystyrene microspheres having dimpled surface structures was demonstrated using amphiphilic and hydrophobic silica particles as structure-directing agents.

Carbon nanotube networks by chemical vapor deposition

We have demonstrated assembly of two- and three-dimensional networks of single-walled carbon nanotubes (SWNTs) using a microsphere assembly approach. The catalyst microcapsules are made from the solution based impregnation of uniform diameter, porous polystyrene microspheres. Chemical vapor deposition on the microcapsule arrays produces highly interconnected SWNT networks. Varying the microsphere diameter and catalyst solution composition allows varying the pattern spacing, catalyst yield, and network interconnectivity.

Plasmachemical Amine Functionalization of Porous Polystyrene Beads: The Importance of Pore Architecture

The functionalization of different types of porous polystyrene microspheres using allylamine plasmas has been explored using a combination of Fmoc derivatization chemistry and cross-sectional Raman microscopy. Higher amine group loadings are obtained for small particles with large internal pore diameters.