Showing papers on "Polystyrene published in 2016"

Systematic Alkaline Stability Study of Polymer Backbones for Anion Exchange Membrane Applications

Abstract: Anion exchange membranes are an important component in alkaline electrochemical energy conversion and storage devices, and their alkaline stability plays a crucial role for the long-term use of these devices. Herein, a systematic study was conducted for the analysis of polymer backbone chemical stability in alkaline media. Nine representative polymer structures including poly(arylene ether)s, poly(biphenyl alkylene)s, and polystyrene block copolymers were investigated for their alkaline stability. Polymers with aryl ether bonds in their repeating unit showed poor chemical stability when treated with KOH and NaOCH3 solutions, whereas polymers without aryl ether bonds [e.g., poly(biphenyl alkylene)s and polystyrene block copolymers] remained stable. Additional NMR studies and density functional theory (DFT) calculations of small molecule model compounds that mimic the chemical structures of poly(arylene ether)s confirmed that electron-withdrawing groups near to the aryl ether bonds in the repeating unit acc...

Sorption of polycyclic aromatic hydrocarbons to polystyrene nanoplastic

Abstract: Microplastic has become an emerging contaminant of global concern. Bulk plastic can degrade to form smaller particles down to the nanoscale (<100 nm), which are referred to as nanoplastics. Because of their high surface area, nanoplastic may bind hydrophobic chemicals very effectively, increasing their hazard when such nanoplastics are taken up by biota. The present study reports distribution coefficients for sorption of polycyclic aromatic hydrocarbons (PAHs) to 70 nm polystyrene in freshwater, and PAH adsorption isotherms spanning environmentally realistic aqueous concentrations of 10(-5) μg/L to 1 μg/L. Nanopolystyrene aggregate state was assessed using dynamic light scattering. The adsorption isotherms were nonlinear, and the distribution coefficients at the lower ends of the isotherms were very high, with values up to 10(9) L/kg. The high and nonlinear sorption was explained from π-π interactions between the planar PAHs and the surface of the aromatic polymer polystyrene and was higher than for micrometer-sized polystyrene. Reduction of nanopolystyrene aggregate sizes had no significant effect on sorption, which suggests that the PAHs could reach the sorption sites on the pristine nanoparticles regardless of the aggregation state. Pre-extraction of the nanopolystyrene with C18 polydimethylsiloxane decreased sorption of PAHs, which could be explained by removal of the most hydrophobic fraction of the nanopolystyrene. Environ Toxicol Chem 2016;35:1650-1655. © 2015 SETAC.

Organic Polymer Dots as Photocatalysts for Visible Light‐Driven Hydrogen Generation

Abstract: For the first time, organic semiconducting polymer dots (Pdots) based on poly[(9,9'-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1', 3} thiadiazole)] (PFBT) and polystyrene grafting with carboxyl-gr ...

All‐Polystyrene 3D‐Printed Electrochemical Device with Embedded Carbon Nanofiber‐Graphite‐Polystyrene Composite Conductor

Abstract: Carbon nanofibres (CNFs) and graphite flake microparticles were added to thermoplastic polystyrene polymer with the aim of making new conductive blends suitable for 3D-printing. Various polymer/carbon blends were evaluated for suitability as printable, electroactive material. An electrically conducting polystyrene composite was developed and used with commercially available polystyrene (HIPS) to manufacture electrodes suitable for electrochemical experiments. Electrodes were produced and evaluated for cyclic voltammetry of aqueous 1,1’-ferrocenedimethanol and differential pulse voltammetry detection of aqueous Pb2+ via anodic stripping. A polystyrene/CNF/graphite (80/10/10 wt%) composite provides good conductivity and a stable electrochemical interface with well-defined active geometric surface area. The printed electrodes form a stable interface to the polystyrene shell, give good signal to background voltammetric responses, and are reusable after polishing.

Functionalized Carbon Nanotubes with Phosphorus- and Nitrogen-Containing Agents: Effective Reinforcer for Thermal, Mechanical, and Flame-Retardant Properties of Polystyrene Nanocomposites

Abstract: Aminated multiwalled carbon nanotubes (A-MWCNT) were reacted with diphenylphosphinic chloride (DPP-Cl) to prepare the functionalized MWCNT (DPPA-MWCNT). A-MWCNT and DPPA-MWCNT were respectively mixed with polystyrene (PS) to obtain composites through the melt compounding method. SEM observations demonstrated that the DPPA-MWCNT nanofillers were more uniformly distributed within the PS matrix than A-MWCNT. PS/DPPA-MWCNT showed improved thermal stability, glass transition temperature, and tensile strength in comparison with PS/A-MWCNT, resulting from good dispersion and interfacial interactions between DPPA-MWCNT and PS matrix. The incorporation of DPPA-MWCNT to PS significantly reduced peak heat release rate, smoke production rate, and carbon monoxide and carbon dioxide release in cone calorimeter tests. The enhanced fire-retardant properties should be ascribed to the barrier effect of carbon nanotubes, which could provide enough time for DPPA-MWCNT and its functionalized groups to trap the degrading polym...

Hollow Sphere TiO2–ZrO2 Prepared by Self-Assembly with Polystyrene Colloidal Template for Both Photocatalytic Degradation and H2 Evolution from Water Splitting

Abstract: On the basis of a self-assembly technique with polystyrene (PS) spheres as colloidal template, the composite TiO2–ZrO2 hollow spheres are synthesized by combining a water bath with a calcining postprocessing method. XRD, UV–vis/DRS, XPS, SEM–EDS, TEM, HR-TEM, and N2 adsorption–desorption measurements are employed to characterize the composition, structure, and morphology of TiO2–ZrO2 hollow spheres. The results show that TiO2–ZrO2 hollow spheres are mainly TiO2 anatase and retain well the spherical structure of the PS crystal template, whose shell is closely packed by TiO2–ZrO2 nanoparticles, with thickness of ca. 24 nm. The combination of TiO2 and ZrO2 and the special hollow structure are beneficial to improve the photocatalytic activity. TiO2–ZrO2 hollow spheres have remarkable photocatalytic properties under UV light, simulated sunlight, and microwave-assisted three different modes, which can also degrade organic pollutants of different structures. In addition, the H2 evolution quantity in 8 h, which i...

Spin-Casting Polymer Brush Films for Stimuli-Responsive and Anti-Fouling Surfaces.

Abstract: Surfaces modified with amphiphilic polymers can dynamically alter their physicochemical properties in response to changes of their environmental conditions; meanwhile, amphiphilic polymer coatings with molecular hydrophilic and hydrophobic patches, which can mitigate biofouling effectively, are being actively explored as advanced coatings for antifouling materials. Herein, a series of well-defined amphiphilic asymmetric polymer brushes containing hetero side chains, hydrophobic polystyrene (PS) and hydrophilic poly(ethylene glycol) (PEG), was employed to prepare uniform thin films by spin-casting. The properties of these films were investigated by water contact angle, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and quartz crystal microbalance (QCM). AFM showed smooth surfaces for all films with the roughness less than 2 nm. The changes in water contact angle and C/O ratio (XPS) evidenced the enrichment of PEG or PS chains at film surface after exposed to selective solvents, indicative of stimuli- responsiveness. The adsorption of proteins on PEG functionalized surface was quantified by QCM and the results verified that amphiphilic polymer brush films bearing PEG chains could lower or eliminate protein-material interactions and resist to protein adsorption. Cell adhesion experiments were performed by using HaCaT cells and it was found that polymer brush films possess good antifouling ability.

MOF-5-Polystyrene: Direct Production from Monomer, Improved Hydrolytic Stability, and Unique Guest Adsorption

Abstract: An unprecedented mode of reactivity of Zn4O-based metal–organic frameworks (MOFs) offers a straightforward and powerful approach to polymer-hybridized porous solids. The concept is illustrated with the production of MOF-5-polystyrene wherein polystyrene is grafted and uniformly distributed throughout MOF-5 crystals after heating in pure styrene for 4–24 h. The surface area and polystyrene content of the material can be fine-tuned by controlling the duration of heating styrene in the presence of MOF-5. Polystyrene grafting significantly alters the physical and chemical properties of pristine MOF-5, which is evident from the unique guest adsorption properties (solvatochromic dye uptake and improved CO2 capacity) as well as the dramatically improved hydrolytic stability of composite. Based on the fact that MOF-5 is the best studied member of the structure class, and has been produced at scale by industry, these findings can be directly leveraged for a range of current applications.

Trimodally porous SnO2 nanospheres with three-dimensional interconnectivity and size tunability: a one-pot synthetic route and potential application as an extremely sensitive ethanol detector

Abstract: The rapid and effective transfer of chemical reactants to solid surfaces through porous structures is essential for enhancing the performance of nanomaterials for various energy and environmental applications. In this paper, we report a facile one-pot spray pyrolysis method for preparing highly reactant-accessible and porous SnO2 spheres, which have three-dimensionally interconnected and size-tunable trimodal (microscale, mesoscale and macroscale) pores. For this synthetic method, macroscale polystyrene spheres and mesoscale-diameter, long carbon nanotubes were used as sacrificial templates. The promising potential of the SnO2 spheres with trimodal pores (sizes ≈3, 20 and 100 nm) was demonstrated by the unprecedentedly high response to several p.p.b. levels of ethanol. Such an ultrahigh response to ethanol is explained with respect to the hierarchical porosity and pore-size-dependent gas diffusion mechanism. Spray pyrolysis has been used to prepare tin dioxide nanospheres that contain size-tunable ‘trimodal’ pores. To enhance the performance of porous nanostructures in various energy and environmental applications involving reactions at surfaces and interfaces, it is desirable to gain precise control of multimodal pores in nanostructures. Jong-Heun Lee at Korea University and co-workers have used a simple ‘one-pot’ spray pyrolysis method to produce tin dioxide nanospheres with three levels of pore sizes. Aqueous droplets containing a metal salt, macroscale polystyrene spheres and mesoscale-diameter carbon nanotubes were subjected to pyrolysis, which decomposed the metal salt and polystyrene. Heat treatment then decomposed the carbon nanotubes. The potential of this method was demonstrated by using tin dioxide spheres containing pores with sizes of 3, 20 and 100 nanometres to detect ethanol at levels of several parts per billion. Trimodally porous SnO2 nanospheres with pore sizes of 3, 20 and 100 nm were prepared with facile one-pot spray pyrolysis and their potential for extremely sensitive ethanol detector was demonstrated. The precise control over, as well as the tuning of, multimodal pores in metal oxide nanostructures provides a new and general strategy for enhancing the performance of nanomaterials for various energy and environmental applications.

Anhydrous Proton Conducting Polymer Electrolyte Membranes via Polymerization-Induced Microphase Separation

Abstract: Solid-state polymer electrolyte membranes (PEMs) exhibiting high ionic conductivity coupled with mechanical robustness and high thermal stability are vital for the design of next-generation lithium-ion batteries and high-temperature fuel cells. We present the in situ preparation of nanostructured PEMs incorporating a protic ionic liquid (IL) into one of the domains of a microphase-separated block copolymer created via polymerization-induced microphase separation. This facile, one-pot synthetic strategy transforms a homogeneous liquid precursor consisting of a poly(ethylene oxide) (PEO) macro-chain-transfer agent, styrene and divinylbenzene monomers, and protic IL into a robust and transparent monolith. The resulting PEMs exhibit a bicontinuous morphology comprising PEO/protic IL conducting pathways and highly cross-linked polystyrene (PS) domains. The cross-linked PS mechanical scaffold imparts thermal and mechanical stability to the PEMs, with an elastic modulus approaching 10 MPa at 180 °C, without sacrificing the ionic conductivity of the system. Crucially, the long-range continuity of the PEO/protic IL conducting nanochannels results in an outstanding ionic conductivity of 14 mS/cm at 180 °C. We posit that proton conduction in the protic IL occurs via the vehicular mechanism and the PEMs exhibit an average proton transference number of 0.7. This approach is very promising for the development of high-temperature, robust PEMs with excellent proton conductivities.

All-Polymer Solar Cells Employing Non-Halogenated Solvent and Additive

Abstract: Herein, we report an all-polymer solar cell with a PCE of over 5% fabricated with non-halogenated solvent. Our method of polymer side-chain engineering using polystyrene enhanced the solubility of polymers in toluene. The phase separation size of the polymer–polymer blend was controlled by tuning the additive concentration. Three different additives were employed and studied. To the best of our knowledge, this is the highest performing all-polymer solar cell fabricated with both non-halogenated solvent and non-halogenated additive, which highlights its potential toward environmentally friendly manufacturing of all-polymer organic solar cells.

Smart protection provided by epoxy clear coating doped with polystyrene microcapsules containing silanol and Ce (III) ions as corrosion inhibitors

Abstract: Polystyrene microcapsules loaded with octylsilanol and Ce (III) ions as core materials have been synthesized by solvent evaporation method from a double emulsion. The obtained microcapsules were doped into an epoxy clear coating and applied on carbon steel. A mechanical defect was done on the coating, in order to evaluate the self-healing effect. The self-healing effect provided by this system was studied by electrochemical impedance spectroscopy (EIS), scanning vibrating electrode technique (SVET) and accelerated corrosion tests in salt spray chamber (SSC) of the coated samples with a clear epoxy coating formulated with 30% w/w of polystyrene microcapsules. For the samples with artificial defect, the performance of the microcapsule-formulated coating was better than the formulated without microcapsules, due to the release of the inhibitors, even after 120 h of immersion in 0.05 molL− 1 NaCl solution. The SVET results are in good agreement with the EIS results, showing the corrosion inhibition in the artificial defects done in coated samples and endorsed the marked self-healing effect. The accelerated tests in salt spray chamber have shown less corrosion products and minor blistering around the scratch for the coating formulated with inhibitor containing microcapsules after 144 h of exposure.

Cell nucleation in dominating formation of bimodal cell structure in polypropylene/polystyrene blend foams prepared via continuous extrusion with supercritical CO2

Abstract: It is generally difficult to predict the cell structure foamed from a binary polymer blend compared to a single polymer, as many factors in polymer blends add to the complexity of the foaming process without easy control, such as blend morphology, blend viscosity, and solubility and diffusivity of the foaming agent, etc. In this study, polypropylene (PP)/polystyrene (PS) blend foams with a bimodal cell structure were prepared by using supercritical carbon dioxide (scCO 2 ) in continuous extrusion. By comparison of the cell structure of blend foams before and after extraction, it was found that the large cells were mainly formed in PS phase, while the small ones were mostly formed in PP phase. A possible mechanism was proposed to explain the formation of the bimodal cell structure. It was believed that a prominent difference in cell nucleation in the two phases of the PP/PS blends was required for the formation of bimodal cell structure. The proposed mechanism was confirmed by further experimental results, which showed that the bimodal cell structure could be changed by altering the nucleation ability in PP phase and PS phase through changing experimental conditions, such as the content of scCO 2 and the pressure drop, or through applying a heterogeneous nucleating agent.

Highly stable poly(ethylene glycol)-grafted alkaline anion exchange membranes

Abstract: A mechanically and chemically stable poly(ethylene glycol) (PEG)-grafted poly(styrene-ethylene-co-butylene-styrene) (SEBS)-based alkaline anion exchange membrane (AAEM) was designed, prepared and characterized. When subjected to tensile strain, the elongation at breaking of these SEBS-based AAEMs was up to 500%, a value 80 times greater than that of an AAEM using polystyrene as the main chain. Remarkably, the ion exchange capacity (IEC), conductivity, dimensions and mechanical properties of this AAEM could remain almost unchanged in 2.5 M KOH at 60 °C for about 3000 h, indicating the excellent alkaline stability of the PEG-grafted SEBS-based AAEMs. As confirmed by TEM, the grafting of PEG could enlarge the size of the ion-conducting channels, significantly enhancing the conductivity of these AAEMs (80 °C, from 29.2 mS cm−1 to 51.9 mS cm−1). Furthermore, the peak power density of an H2/O2 single fuel cell using this SEBS-based AAEM was up to 146 mW cm−2 at 50 °C. Based on these outstanding properties, this membrane has potential application not only for fuel cells, but also for other electrochemical energy conversion and storage devices, such as redox flow and alkaline ion batteries.

Major Impact of Cyclic Chain Topology on the Tg-Confinement Effect of Supported Thin Films of Polystyrene

Abstract: High purity cyclic PS (c-PS) samples with number-average molecular weight (MW) of 3.4 and 9.1 kg/mol were synthesized via atom transfer radical polymerization and “click” chemistry with narrow MW distribution. Bulk glass transition temperature (Tg) measured by differential scanning calorimetry exhibited a much weaker MW dependence for c-PS relative to its linear precursor and anionically polymerized linear PS (A-PS). Using ellipsometry and fluorescence spectroscopy, major differences were observed in the Tg-confinement effect in c-PS films supported on silicon substrates compared to A-PS. Whereas a large Tg reduction with confinement is commonly observed for A-PS supported on silica, within error, no confinement effect is seen in c-PS/3.4k films on Si/SiOx substrates down to 21 nm thickness. Although the c-PS linking group contains nitrogen and oxygen atoms potentially able to undergo hydrogen bonding, Tg is invariant with confinement for c-PS/3.4k or slightly reduced for c-PS/9.1k regardless of the level...