Porous Polystyrene Research Articles

Effect of ferrocene on the fabrication of honeycomb-patterned porous polystyrene films and silver functionalization of the film

Honeycomb-patterned (HCP) porous polystyrene (PS) film was fabricated by the breath figure method with inclusion of ferrocene in the PS solution for silver (Ag)-functionalization. Ag-functionalized HCP porous PS film was obtained by immersing the fabricated film in aqueous silver nitrate solution through interfacial reduction by ferrocene. The addition of ferrocene in the polymer solution also affected the morphology of the HCP porous film during the fabrication process. Depending on the used ferrocene concentration, morphology of the obtained Ag morphology on the film surface was different. By increasing the ferrocene concentration the reduced silver particles changed to silver nanowire without much aggregation and also increased the conductivity of the films. This method of silver-functionalization on the polymer film unleashes the futuristic applications in interdisciplinary fields such as substrates for Raman scattering and antibacterial studies.

Sensor for ampicillin based on a microwave electrodynamic resonator

The paper describes a new biological sensor which represents a resonator based on a segment of a rectangular waveguide of 8 GHz band with shear dimensions of 28.5 × 12.6 mm2. On one side, the resonator is bounded by a metallic short-circuited wall; on the other side, it is bounded by a lithium niobate plate with a porous polystyrene film. This film, applied by centrifugation and modified in high-frequency discharge plasma in argon, was used to immobilize cells of Escherichia coli K-12. This resonator was connected through a coaxial-waveguide adapter to the S parameter meter, by means of which the reflection coefficient S11 in the plane of the lithium niobate plate was measured. The addition of an aqueous solution of ampicillin at 4–50 μg/ml to immobilized cells led to a significant change in the reflection coefficient of S11 from − 10.15 dB to − 15.09 dB. At the same time, the resonance frequency changed insignificantly within the range 8.06–8.068 GHz. The optimal time for modifying the polystyrene film for obtaining the required porosity and the optimal time for the immobilization of the bacterial cells were determined. The immobilized cells retained their activity for 4 months at a temperature of 4 °C. The study showed the promise of such a biosensor to determine β-lactam antibiotics in aqueous solutions by using ampicillin as an example. The limit of detection of the developed biosensor with respect to ampicillin was established (4 μg/ml).

Porous Polystyrene Monoliths Prepared from in Situ Simultaneous Interpenetrating Polymer Networks: Modulation of Morphology by Polymerization Kinetics.

Semi-interpenetrating polymer networks (semi-IPNs) were prepared by in situ simultaneous orthogonal polymerizations, where the linear poly(ε-caprolactone) (PCL) was synthesized by ring-opening polymerization of ε-caprolactone and the poly(styrene-co-divinylbenzene) (PS) network was formed by free-radical polymerization of styrene/divinylbenzene. Semi-IPNs were used as the precursors for the preparation of porous PS monoliths. To this end, the PCL domains were selectively removed by hydrolysis under basic conditions. By changing the amount of organocatalyst used for the ring-opening polymerization of ε-caprolactone, the relative polymerization kinetics of both monomers was varied, which has a pronounced effect on the morphology of thus-obtained PS frameworks.

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

Silver-modified porous polystyrene sulfonate derived from Pickering high internal phase emulsions for capturing lithium-ion.

Adsorption separation based on porous polystyrene sulfonate is an important method of extracting lithium ion (Li+). In this work, silver-modified porous polystyrene sulfonate (PHIPEs-SS-Ag) derived from Pickering high internal phase emulsions was fabricated for the selective binding of Li+. PHIPEs-SS-Ag possessed porous polymer matrix, sufficient sulfonic acid functional groups, and uniformly immobilized silver particles, which were beneficial for improving mass transfer, binding amount and antifouling performance. In batch mode experiments, the adsorption capacity reached a maximum value (i.e. 14.09 mg g−1) under alkaline conditions, and the adsorption mechanism between PHIPEs-SS-Ag and Li+ was electrostatic attraction. PHIPEs-SS-Ag exhibited fast binding kinetics at 25 °C (i.e. 300 min), and the maximum monolayer adsorption amount from the Langmuir model for Li+ are 59.85 mg g−1, 35.06 mg g−1, and 27.09 mg g−1 at 15 °C, 25 °C, and 35 °C, respectively. Moreover, PHIPEs-SS-Ag displayed excellent selectivity for Li+ in the presence of K+, Mg2+, and Na+, and maintained 80.71% of the initial adsorption capacity after seven sequential cycles of adsorption–regeneration. Therefore, this work opened up a universal route for the development of composite adsorbents for the specific separation of Li+.

Treatment of Polystyrene in Sub- and Supercritical Media

The treatment of polystyrene in sub- and supercritical (SC) freons was studied in comparison with processes in supercritical carbon dioxide. Subcritical freon R22 was shown to be much more effective in saturating polystyrene than subcritical R410a and SC R23 and CO2. Subsequent thermal treatment of the samples saturated with R22 gave a polymer with a developed porous structure and an average pore size of up to 250 μm. The results of this study can be used to develop new technologies for the preparation of porous polystyrene.

Unexpected Favorable Role of Ca2+ in Phosphate Removal by Using Nanosized Ferric Oxides Confined in Porous Polystyrene Beads

Polystyrene-based nanoferric oxide composite is a representative nanomaterial successfully applied in scale-up water decontamination for arsenic and phosphorus. However, little is available on the effect of solution chemistry (for instance, the coexisting Ca2+) on the long-term performance of the nanocomposite. In this study, we carried out 20 cyclic runs of phosphate adsorption-desorption on a polymer-supported ferric nanocomposite HFO@201. Unexpectedly, an enhanced phosphate removal was observed in the presence of Ca2+, which is quite different from its adverse effect on phosphate capture by granular ferric oxide. Further mechanistic studies revealed that enhanced phosphate removal was mainly realized via the Ca-P coprecipitation inside the networking pores of HFO@201 as well as the possible formation of the multiple Fe-P-Ca-P complex. The complex formation led to a distinct increase in P adsorption, and the coprecipitation, driven by the accumulated OH- in confined pores during phosphate adsorption and alkaline regeneration, favored P removal via the formation of amorphous calcium phosphate (ACP) and hydroxyapatite inside. TEM-EDS spectra indicated that coprecipitation did not occur on the surface of loaded nano-HFO, greatly mitigating its adverse effect on P adsorption on the surface of nano-HFO. Fixed-bed column study showed that the presence of Ca2+ increased the effective treatable volume of HFO@201 toward P-containing influents by ∼70%. This study is believed to shed new insights into the effect of solution chemistry on similar nanocomposites for advanced water treatment.

Fabrication of hollow and porous polystyrene fibrous membranes by electrospinning combined with freeze‐drying for oil removal from water

ABSTRACTA novel method was proposed to fabricate hollow and surface porous polystyrene (PS) fibrous membranes for the removal of oil from water. Spinning solutions were prepared by using camphene and tetraethoxysilane (TEOS) as pore‐forming agents, and hollow PS fibers with 100–400 nm pores on the surface were fabricated by electrospinning and freeze‐drying. The distribution and volatilization of camphene and TEOS, as well as the drying behavior of solvents in high relative humidity, were important factors in forming the porous structure of PS fibers. The specific surface area of obtained PS fibrous membranes was twice that of conventional electrospun PS fibrous membranes and displayed superhydrophobic properties. Moreover, the large adsorption storage space was formed due to the hollow structure and porous surface of PS fibers. The maximum oil adsorption capacity of the porous PS fibrous membrane was 105.4 g g−1, and was larger than that of the conventional PS fibrous membrane after repeated five times, thus making it a promising tool for oil spill cleanups. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47262.

Laser-driven hydrothermal wave speed in low-Z foam of overcritical density

The speed of the laser-supported hydrothermal wave is experimentally measured in porous polystyrene with overcritical average density. The results of the experiments are in agreement with the simulations performed with the MULTI-FM code, modeling the state of partly homogenized plasma. The measured velocity is 2 times smaller than the shock wave velocity calculated in simulations under the same conditions of laser irradiation in a homogeneous substance of the same density. The obtained results allow us to better investigate the possibility of using porous matter of overcritical density as an effective absorber-ablator in laser thermonuclear fusion targets.

Osteogenic Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells in Electrospun Silica Nonwoven Fabrics.

Silica nonwoven fabrics (SNFs) with enough mechanical strength are candidates as implantable scaffolds. Culture of cells therein is expected to affect the proliferation and differentiation of the cells through cell–cell and cell–SNF interactions. In this study, we examined three-dimensional (3D) SNFs as a scaffold of mesenchymal stem cells (MSCs) for bone tissue engineering applications. The interconnected highly porous microstructure of 3D SNFs is expected to allow omnidirectional cell–cell interactions, and the morphological similarity of a silica nanofiber to that of a fibrous extracellular matrix can contribute to the promotion of cell functions. 3D SNFs were prepared by the sol–gel process, and their mechanical properties were characterized by the compression test and rheological analysis. In the compression test, SNFs showed a compressive elastic modulus of over 1 MPa and a compressive strength of about 200 kPa. These values are higher than those of porous polystyrene disks used for in vitro 3D cell culture. In rheological analysis, the elastic modulus and fracture stress were 3.27 ± 0.54 kPa and 25.9 ± 8.3 Pa, respectively. Then, human bone marrow-derived MSCs were cultured on SNFs, and the effects on proliferation and osteogenic differentiation were evaluated. The MSCs seeded on SNF proliferated, and the thickness of the cell layer became over 80 μm after 14 days of culture. The osteogenic differentiation of MSCs on SNFs was induced by the culture in the commercial osteogenic differentiation medium. The alkaline phosphatase activity of MSCs on SNFs increased rapidly and remained high up to 14 days and was much higher than that on two-dimensional tissue culture-treated polystyrene. The high expression of RUNX2 and intense staining by alizarin red s after differentiation supported that SNFs enhanced the osteogenic differentiation of MSCs. Furthermore, permeation analysis of SNFs using fluorescein isothiocyanate-dextran suggested a sufficient permeability of SNFs for oxygen, minerals, nutrients, and secretions, which is important for maintaining the cell viability and vitality. These results suggested that SNFs are promising scaffolds for the regeneration of bone defects using MSCs, originated from highly porous and elastic SNF characters.

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.

Formylated polystyrene for the fabrication of pore selective aldehyde group functionalized honeycomb patterned porous polystyrene films

ABSTRACTFormylated polystyrene (PS‐CHO) was synthesized by chemical modification of polystyrene (PS) for the fabrication of honeycomb patterned (HCP) porous PS films with aldehyde group functionalized pores via breath figure method under humid conditions. The incorporation of hydrophilic aldehyde group affected the hydrophobicity of PS solution and assisted the self‐assembly of PS‐CHO toward pore. The presence of aldehyde groups in the films were proved by the post treatment with Tollens's reagent, which results in silver decoration at pores. The morphology of the films before and after silver decoration was studied by scanning electron microscopy analysis. The pore selectively self‐assembled aldehyde groups in the patterned porous films can have many applications as a reactive substrate in biomaterials and chemical moieties adhesion. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1181–1192

Next generation in vitro liver model design: Combining a permeable polystyrene membrane with a transdifferentiated cell line

Herein we describe the manufacture and characterisation of biocompatible, porous polystyrene membranes, suitable for cell culture. Though widely used in traditional cell culture, polystyrene has not been used as a hollow fibre membrane due to its hydrophobicity and non-porous structure.Here, we use microcrystalline sodium chloride (4.7 ± 1.3 µm) to control the porosity of polystyrene membranes and oxygen plasma surface treatment to reduce hydrophobicity. Increased porogen concentration correlates to increased surface pore density, macrovoid formation, gas permeability and mean pore size, but a decrease in mechanical strength. For tissue engineering applications, membranes spun from casting solutions containing 40% (w/w) sodium chloride represent a compromise between strength and permeability, having surface pore density of 208.2 ± 29.7 pores/mm2, mean surface pore size of 2.3 ± 0.7 µm, and Young's modulus of 115.0 ± 8.2 MPa.We demonstrate the biocompatibility of the material with an exciting cell line-media combination: transdifferentiation of the AR42J-B13 pancreatic cell line to hepatocyte-like cells. Treatment of AR42J-B13 with dexamethasone/oncostatin-M over 14 days induces transdifferentiation towards a hepatic phenotype. There was a distinct loss of the pancreatic phenotype, shown through loss of expression of the pancreatic marker amylase, and gain of the hepatic phenotype, shown through induction of expression of the hepatic markers transferrin, carbamoylphosphate synthetase and glutamine synthetase.The combination of this membrane fabrication method and demonstration of biocompatibility of the transdifferentiated hepatocytes provides a novel, superior, alternative design for in vitro liver models and bioartificial liver devices.

Antimicrobial Porous Surfaces Prepared by Breath Figures Approach.

Herein, efficient antimicrobial porous surfaces were prepared by breath figures approach from polymer solutions containing low content of block copolymers with high positive charge density. In brief, those block copolymers, which were used as additives, are composed of a polystyrene segment and a large antimicrobial block bearing flexible side chain with 1,3-thiazolium and 1,2,3-triazolium groups, PS54-b-PTTBM-M44, PS54-b-PTTBM-B44, having different alkyl groups, methyl or butyl, respectively. The antimicrobial block copolymers were blended with commercial polystyrene in very low proportions, from 3 to 9 wt %, and solubilized in THF. From these solutions, ordered porous films functionalized with antimicrobial cationic copolymers were fabricated, and the influence of alkylating agent and the amount of copolymer in the blend was investigated. Narrow pore size distribution was obtained for all the samples with pore diameters between 5 and 11 µm. The size of the pore decreased as the hydrophilicity of the system increased; thus, either as the content of copolymer was augmented in the blend or as the copolymers were quaternized with methyl iodide. The resulting porous polystyrene surfaces functionalized with low content of antimicrobial copolymers exhibited remarkable antibacterial efficiencies against Gram positive bacteria Staphylococcus aureus, and Candida parapsilosis fungi as microbial models.

Amine-impregnated porous nanofiber membranes for CO2 capture

Global warming is a worldwide issue, mainly caused by excessive emission of carbon dioxide (CO2), thus, demands the development of robust and flexible sorbents with consider CO2 capturing capacity. Herein, we report an easy and facile two-step fabrication of hierarchically structured and highly porous polystyrene (PS)/polyurethane (PU) electrospun nanofiber membrane impregnated with various amines for post-combustion CO2 capture. Synthesized porous nanofiber membranes have highly flexible and strong mechanical characteristics. The comparative analysis of porous membranes functionalized with three functional amines shows that low molecular weight polyethyleneimine (PEIL) impregnated porous nanofiber membranes offer relatively higher CO2 adsorption (1.64 mmol/g) at 40 °C. In addition, optimized samples exhibit excellent regenerability, (≥ 90% of their original value) even after 19 adsorption-desorption cycles showing a stable and durable CO2 capture performance. This work paves the way for developing electrospun nanofiber membranes capable of efficient CO2 adsorption.

Porous carbon derived from waste polystyrene foam for supercapacitor

Polystyrene, one of the classical plastic, has caused serious environmental problems due to overuse and inability to recycle effectively. Transforming it into functional carbon materials is one of the effective ways to recycle polystyrene and other waste plastics, which has drawn the attention. In this study, we have developed a facile and efficient method for the preparation of three-dimensional (3D) network structure porous carbon (PC) via the Friedel–Crafts reaction with waste polystyrene serves as carbon source. Notably, the constructed carbonyl (–CO–) cross-linking bridges between the linear polystyrenes provide the resulting hierarchical porous polystyrene with a high cross-linking density and amounts of oxygen atoms to achieve the carbonizability of cross-linking polystyrene framework. Moreover, silica particles created more porous structure for carbon material. The prepared PC showed large specific surface area and 3D porous structure and exhibited good capacitance and electrochemical stability as electrode materials for supercapacitor.

Electrowetting‐Induced Stiction Switch of a Microstructured Wire Surface for Unidirectional Droplet and Bubble Motion

AbstractDirectional motion of fluid droplets is attracting considerable research attention. Despite much progress in this field, electrowetting‐based stiction switch that drives unidirectional transport of an underwater oil droplet or air bubble on a wire surface is still a challenge to realize. Here, a strategy to collect and unidirectionally transport an underwater oil droplet or air bubble on a porous polystyrene (PS) film‐coated copper wire surface through the combination of electrowetting‐induced stiction switch and buoyancy is demonstrated. The porous PS film‐coated copper wire fabricated by the breath figure method at a relative humidity of 75% can catch and hold an underwater oil droplet or air bubble without applied voltage. With increasing applied voltage, the stiction of the underwater oil droplet or air bubble on the porous PS film surface weakens because water increasingly wets the film surface. The underwater oil droplet or air bubble can move unidirectionally on the porous PS film‐coated wire surface upward or downward at a voltage larger than its critical voltage according to whether its density is lower or higher than that of water. This work should aid the development of devices displaying electrowetting‐based changes for use in fluid collection, manipulation, unidirectional transfer, release, and removal.

The Stability of Highly Concentrated Water-in-Oil Emulsions and Structure of Highly Porous Polystyrene Produced from Them

The porosity of polymer materials produced by polymerizing dispersion media of highly concentrated emulsions may be predicted, provided that the emulsions are stable. The study of the stability of water-in-oil (W/O) emulsions containing styrene as a dispersion medium at 25 and 65°C has shown that emulsions with a dispersed phase fraction of 0.75 and sorbitan monooleate concentrations of 1.5–20.0 vol % are stable to coalescence but are unstable to sedimentation. Emulsions with a dispersed phase fraction of 0.95 are stable to both coalescence and sedimentation at sorbitan monooleate concentrations of 10–20 vol %. Open-pore polymer materials are formed from emulsions with dispersed phase fractions of 0.75 and 0.95 at sorbitan monooleate concentrations of 2.0–3.5 and 10–12 vol %, respectively. At a dispersed phase fraction of 0.75 and a sorbitan monooleate concentration of <2 vol %, a multiple O/W/O emulsion is formed, the polymerization of which yields a porous polymer material containing spherical polystyrene particles inside pores. At higher surfactant concentrations in emulsions with dispersed phase fractions of 0.75 and 0.95 partly destroyed porous materials are formed.

Multi-porous quaternized chitosan/polystyrene microbeads for scalable, efficient heparin recovery

Heparin is a commercially valuable polysaccharide used as an anticoagulant for surgical procedures. However, it is difficult to isolate at high concentrations from the complex tissues from which it is derived. To address this problem, we fabricated novel porous polystyrene (PS) supported chitosan (CS)-coated microbeads by electrostatic assembly for the efficient, scalable, and selective recovery of heparin. These CS/PS microbeads were further reacted and quaternized using glycidyltrimethylammonium chloride to improve their heparin adsorption efficiency at high pH values. Additionally, a tetrahydrofuran/n-heptane treatment was used to introduce multi-porosity throughout the quaternized-CS/PS microbead structure, increasing the functional surface area. Scanning electron microscopy was used to evaluate the effects of pre- and post-treatments on the bead surface morphology. The adsorption efficiency of the CS/PS microbeads vs. Amberlite FPA98 Cl resin, a commercially available adsorbent, was evaluated as a function of pH (4.1–9.2). Heparin adsorption was demonstrated to improve with both the introduction of a multi-porous bead structure and the quaternization of the CS/PS microbeads to provide a pH-independent cationic polyelectrolyte character. We also demonstrated that the CS/PS microbeads could be effectively regenerated using a saturated NaCl solution and used for repeated heparin recovery without significant adsorption capacity loss. Moreover, multi-porous quaternized-CS/PS microbeads selectively adsorbed heparin in the presence of bovine serum albumin at pH 9 by adding 0.5 M NaCl to screen electrostatics between the CS and proteins. In addition, microbeads selectively adsorbed heparin in a real sample, composed of a mixture of biological solution containing heparin isolated from porcine intestinal mucosa.

Cagelike porous sulfonated polystyrene@polyaniline composite microspheres for high-performance supercapacitor

The development of novel high-performance electrode materials has become increasingly urgent due to the broad demands on the large-capacity energy storage devices nowadays. In this work, cagelike porous sulfonated polystyrene (cSPS) microspheres are first synthesized as the skeleton structure templates, on which polyaniline (PANI) nanoparticles with a size of about 30 nm are loaded through the in situ polymerization of aniline. The novel cSPS-supported PANI composite microspheres (cSPS@PANI) possess hierarchical meso-/macroporous structure, and their BET specific surface area and pore volume reach the maximum at a moderate PANI mass fraction. The electrochemical performance of cSPS@PANI composite microspheres was evaluated through a three-electrode system with 1 M H2SO4 as the electrolyte. The specific capacitance of the cSPS@PANI composite microspheres can reach as high as 374 F g−1 at a current density of 1 A g−1, and only 11.8% is lost after 500 charge/discharge cycles. Thus, the cSPS@PANI composite microspheres can be potentially used as one of the novel outstanding electrode materials in the fabrication of high-performance energy storage devices.