Showing papers on "Polystyrene published in 2013"
TL;DR: Almost all synthetic polymers require stabilization against adverse environmental effects, and two aspects of degradation are of particular importance: Storage conditions, and Addition of appropriate stabilizers.
Abstract: Exposure to ultraviolet (UV) radiation may cause the significant degradation of many materials. UV radiation causes photooxidative degradation which results in breaking of the polymer chains, produces free radical and reduces the molecular weight, causing deterioration of mechanical properties and leading to useless materials, after an unpredictable time. Polystyrene (PS), one of the most important material in the modern plastic industry, has been used all over the world, due to its excellent physical properties and low-cost. When polystyrene is subjected to UV irradiation in the presence of air, it undergoes a rapid yellowing and a gradual embrittlement. The mechanism of PS photolysis in the solid state (film) depends on the mobility of free radicals in the polymer matrix and their bimolecular recombination. Free hydrogen radicals diffuse very easily through the polymer matrix and combine in pairs or abstract hydrogen atoms from polymer molecule. Phenyl radical has limited mobility. They may abstract hydrogen from the near surrounding or combine with a polymer radical or with hydrogen radicals. Almost all synthetic polymers require stabilization against adverse environmental effects. It is necessary to find a means to reduce or prevent damage induced by environmental components such as heat, light or oxygen. The photostabilization of polymers may be achieved in many ways. The following stabilizing systems have been developed, which depend on the action of stabilizer: (1) light screeners, (2) UV absorbers, (3) excited-state quenchers, (4) peroxide decomposers, and (5) free radical scavengers; of these, it is generally believed that excited-state quenchers, peroxide decomposers, and free radical scavengers are the most effective. Research into degradation and ageing of polymers is extremely intensive and new materials are being synthesized with a pre-programmed lifetime. New stabilizers are becoming commercially available although their modes of action are sometimes not thoroughly elucidated. They target the many possible ways of polymer degradation: thermolysis, thermooxidation, photolysis, photooxidation, radiolysis etc. With the goal to increase lifetime of a particular polymeric material, two aspects of degradation are of particular importance: Storage conditions, and Addition of appropriate stabilizers. A profound knowledge of degradation mechanisms is needed to achieve the goal.
809 citations
TL;DR: A mass-producible mesoporous graphene nanoball fabricated via a precursor-assisted chemical vapor deposition (CVD) technique for supercapacitor application proves the strong potential for use in energy-related areas.
Abstract: A mass-producible mesoporous graphene nanoball (MGB) was fabricated via a precursor-assisted chemical vapor deposition (CVD) technique for supercapacitor application. Polystyrene balls and reduced iron created under high temperature and a hydrogen gas environment provide a solid carbon source and a catalyst for graphene growth during the precursor-assisted CVD process, respectively. Carboxylic acid and sulfonic acid functionalization of the polystyrene ball facilitates homogeneous dispersion of the hydrophobic polymer template in the metal precursor solution, thus, resulting in a MGB with a uniform number of graphene layers. The MGB is shown to have a specific surface area of 508 m2/g and is mesoporous with a mean mesopore diameter of 4.27 nm. Mesopores are generated by the removal of agglomerated iron domains, permeating down through the soft polystyrene spheres and providing the surface for subsequent graphene growth during the heating process in a hydrogen environment. This technique requires only drop...
293 citations
TL;DR: In this paper, Lamellae-forming polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films, with bulk period L 0, were directed to assemble on lithographically nanopatterned surfaces.
Abstract: Lamellae-forming polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films, with bulk period L0, were directed to assemble on lithographically nanopatterned surfaces. The chemical pattern was comprised of “guiding” stripes of cross-linked polystyrene (X-PS) or poly(methyl methacrylate) (X-PMMA) mats, with width W, and interspatial “background” regions of a random copolymer brush of styrene and methyl methacrylate (P(S-r-MMA)). The fraction of styrene (f) in the brush was varied to control the chemistry of the background regions. The period of the pattern was Ls. After assembly, the density of the features (domains) in the block copolymer film was an integer multiple (n) of the density of features of the chemical pattern, where n = Ls/L0. The quality of the assembled PS-b-PMMA films into patterns of dense lines as a function of n, W/L0, and f was analyzed with top-down scanning electron microscopy. The most effective background chemistry for directed assembly with density multiplication corresponded to...
212 citations
TL;DR: In this article, it has been proved that surface adsorption of polymers on cellulose nanocrystal (CN) as compatibilizer, such as hydrophilic polyoxyethylene (PEO), can improve its thermal stability due to the shielding and wrapping of PEO.
Abstract: Impressive mechanical properties and reinforcing capability make cellulose nanocrystal (CN) a promising candidate as biomass nanofiller for the development of polymer-based nanocomposites. With the recent announcement of large-scale CN production, the use of industrial processing techniques for the preparation of CN-reinforced nanocomposites, such as extrusion, is highly required. However, low thermal stability of sulfuric acid-prepared CN limits the processing since most polymeric matrices are processed at temperatures close to 200 °C or above. It has been proved that surface adsorption of polymers on CN as compatibilizer, such as hydrophilic polyoxyethylene (PEO), can improve its thermal stability due to the shielding and wrapping of PEO. However, the weak combination between CN and PEO allows the free movement of surface polymer, which can induce the self-aggregation of CN and microphase separation in composites especially during melt processing. Using carboxylation–amidation reaction, short chains pol...
186 citations
TL;DR: In this article, a flexible thermoelectric generator (TEG) was fabricated on a polyethylene naphthalate film substrate using a printing process, and the TEG generated approximately 55 mW/m2 of power at a temperature difference of 70°C.
Abstract: A flexible thermoelectric generator (TEG) was fabricated on a polyethylene naphthalate film substrate using a printing process. The thermoelectric material used in this study, a composite material consisting of carbon nanotubes (CNTs) and polystyrene, contained approximately 35 vol. % of voids. Because of the reduction in the density of the CNT–polystyrene composite caused by the voids, the TEG was remarkably lightweight (weight per unit area: ≈15.1 mg/cm2). The TEG generated approximately 55 mW/m2 of power at a temperature difference of 70 °C.
168 citations
TL;DR: It is suggested that charged groups in the host resins improve the dispersion of embedded nanoparticles and enhance the reactivity and capacity for sorption of metal ions.
Abstract: A novel hybrid nanomaterial was fabricated by encapsulating ZrO2 nanoparticles into spherical polystyrene beads (MPS) covalently bound with charged sulfonate groups (−SO3–). The resultant adsorbent, Zr–MPS, exhibited more preferential sorption toward Pb(II) than the simple equivalent mixture of MPS and ZrO2. Such observation might be ascribed to the presence of sulfonate groups of the polymeric host, which could enhance nano-ZrO2 dispersion and Pb(II) diffusion kinetics. To further elucidate the role of surface functional groups, we encapsulated nano-ZrO2 onto another two macroporous polystyrene with different surface groups (i.e., −N(CH3)3+/–CH2Cl, respectively) and a conventional activated carbon. The three obtained nanocomposites were denoted as Zr–MPN, Zr–MPC, and Zr–GAC. The presence of −SO3– and −N(CH3)3+ was more favorable for nano-ZrO2 dispersion than the neutral −CH2Cl, resulting in the sequence of sorption capacities as Zr–MPS > Zr–MPN > Zr–GAC > Zr–MPC. Column Pb(II) sorption by the four nanoco...
161 citations
TL;DR: Inspired by the fact that cells and their environments are composed of soft materials—something that has led to soft polymers being exploited in other biological applications, including tissue engineering—Wang and co-workers have replaced the stiff nanowires of their cell-capturing substrate with soft polystyrene nanotubes, leading to softness as an important factor in cell capture and detection.
Abstract: Materials that efficiently isolate cells from whole-blood samples have important diagnostic and therapeutic applications Shutao Wang at the Institute of Chemistry, Chinese Academy of Sciences, China, and co-workers have now devised soft substrates based on the polymer polystyrene that efficiently capture breast cancer cells The researchers previously developed a three-dimensional cell-capture nanostructure comprising a silicon nanowire array coated with an antibody—anti-EpCAM—that detects the epithelial cell adhesion molecule overexpressed by many cancers Now, inspired by the fact that cells and their environments are composed of soft materials—something that has led to soft polymers being exploited in other biological applications, including tissue engineering—Wang and co-workers have replaced the stiff nanowires of their cell-capturing substrate with soft polystyrene nanotubes The resulting polystyrene/anti-EpCAM arrays are significantly more efficient than their silicon counterparts, rapidly detecting breast cancer cells These findings point to softness as an important factor in cell capture and detection
157 citations
TL;DR: A strategy that relies on 'ordered crosslinks' to produce polymeric materials that exhibit a crystalline arrangement that is stable to thermal and solvent treatments, as demonstrated by X-ray powder diffraction and transmission electron microscopy.
Abstract: Chain alignment can significantly influence the macroscopic properties of a polymeric material, but no general and versatile methodology has yet been reported to obtain highly ordered crystalline packing of polymer chains, with high stability. Here, we disclose a strategy that relies on 'ordered crosslinks' to produce polymeric materials that exhibit a crystalline arrangement. Divinyl crosslinkers (2,5-divinyl-terephthalate) were first embedded, as substitutional ligands, into the structure of a porous coordination polymer (PCP), [Cu(terephthalate)triethylenediamine0.5]n. A representative vinyl monomer, styrene, was subsequently polymerized inside the channels of the host PCP. The polystyrene chains that form within the PCP channels also crosslink with the divinyl species. This bridges together the polymer chains of adjacent channels and ensures that, on selective removal of the PCP, the polymer chains remain aligned. Indeed, the resulting material exhibits long-range order and is stable to thermal and solvent treatments, as demonstrated by X-ray powder diffraction and transmission electron microscopy.
155 citations
TL;DR: In this article, the glass transition temperature of the insulating polystyrene (PS) block and the width of the conducting poly(ethylene oxide) (PEO) channel were investigated.
Abstract: The ionic conductivity and glass transition temperatures of nanostructured block copolymer electrolytes composed of polystyrene-b-poly(ethylene oxide) (SEO) doped with lithium bis(trifluoromethanesulfone)imide (LiTFSI) were studied in the small molecular weight limit (between 2.7 and 13.7 kg mol–1). In this range, the annealed conductivity exhibits a nonmonotonic dependence on molecular weight, decreasing with increasing molecular weight in the small molecular weight limit before increasing when molecular weight exceeds about 10 kg mol–1. We show that annealed electrolyte conductivity is affected by two competing factors: the glass transition temperature of the insulating polystyrene (PS) block and the width of the conducting poly(ethylene oxide) (PEO) channel. In the low molecular weight limit, all ions are in contact with both PS and PEO segments. The intermixing between PS and PEO segments is restricted to an interfacial zone of width, λ. Our experiments suggest that λ is about 5 nm. The fraction of io...
152 citations
TL;DR: This paper introduces a facile one-pot method for synthesizing a new structured material, named "ant-cave microball", by continuous ultrasonic spray pyrolysis of polystyrene nanobeads and sucrose, prepared as the first target material for lithium ion batteries.
Abstract: This paper introduces a facile one-pot method for synthesizing a new structured material, named “ant-cave microball”, by continuous ultrasonic spray pyrolysis. The ant-cave-structured microballs are prepared from a colloidal spray solution with polystyrene nanobeads and sucrose. Networking between the nanovoids formed by decomposition of the polystyrene nanobeads results in the formation of nanochannels. The electrochemical properties of these ant-cave-structured MoO3–C microballs, prepared as the first target material for lithium ion batteries, are investigated. The nanochannels are uniformly distributed inside the microballs with MoO3 and carbon components uniformly distributed within the microballs. Further, the microballs have initial discharge and charge capacities of 1212 and 841 mA h g–1, respectively, at a current density of 2 A g–1, and the initial discharge and charge capacities based on the weight of MoO3 (disregarding carbon component) are as high as 1814 and 1259 mA h g–1. The microballs deli...
150 citations
TL;DR: In this paper, the reversible addition-fragmentation chain transfer (RAFT) polymerization of acrylic acid (AA) in water was studied in detail at different pHs using 4-cyano-4-thiothiopropylsulfanyl pentanoic acid (CTPPA) as a control agent and 4,4′-azobis(4-cyanopentaneic acid) (ACPA), as an initiator.
Abstract: The reversible addition–fragmentation chain transfer (RAFT) polymerization of acrylic acid (AA) in water was studied in detail at different pHs using 4-cyano-4-thiothiopropylsulfanyl pentanoic acid (CTPPA) as a control agent and 4,4′-azobis(4-cyanopentanoic acid) (ACPA) as an initiator. Well-defined hydrophilic macromolecular RAFT agents (PAA-CTPPA) were obtained and further used directly in water for the polymerization of styrene. The corresponding polymerization-induced self-assembly (PISA) process was evaluated at different pHs and it was shown that working in acidic conditions (pH = 2.5) led to well-defined amphiphilic block copolymer particles (Đ < 1.4) of small size (below 50 nm). When the pH increased, the control over the growth of the polystyrene (PS) block was gradually lost. Chain extension experiments of PAA-CTPPA with N-acryloylmorpholine (NAM), a hydrosoluble and non-pH sensitive monomer, performed at different pHs showed that the very first addition–fragmentation steps that occurred in wate...
TL;DR: In this paper, a series of poly(isoindigo-dithiophene)-based conjugated polymers with varying amounts of low molecular weight polystyrene (PS) side chains (Mn = 1300 g/mol) via random copolymerization were synthesized.
Abstract: Developing organic photovoltaic systems that possess high efficiency, high reproducibility, and low cost remains a topic of keen investigation. From a molecular design perspective, developing a “multicomponent” copolymerization synthetic approach could potentially afford macromolecular materials encompassing all of the aforementioned desired parameters. Herein, we describe the synthesis of a series of poly(isoindigo-dithiophene)-based conjugated polymers with varying amounts of low molecular weight polystyrene (PS) side chains (Mn = 1300 g/mol) via random copolymerization. We observed better solubility with polymers containing the PS side chains (when compared to their non-PS-side-chain counterparts), hence leading to better batch-to-batch reproducibility in terms of molecular weights. Furthermore, the PS-side-chain-decorated copolymers also demonstrated better thin film processability, without affecting the electronic and optical properties, when the molar percentage of the PS-containing repeating units ...
TL;DR: In this paper, the authors develop quantitative relationships between interfacial surface energy parameters and the dispersion and Tg shifts of PNCs through systematic experiments on an array of hybrid systems spanning a wide range of interfacial interactions.
Abstract: Developing structure–property relationships between the filler/matrix interface chemistry and the dispersion and interface properties of polymer nanocomposites (PNC) is critical to predicting their bulk mechanical, electrical, and optical properties. In this paper we develop quantitative relationships between interfacial surface energy parameters and the dispersion and Tg shifts of PNCs through systematic experiments on an array of hybrid systems spanning a wide range of interfacial interactions. We use four different matrices of surface energies varying from polar to nonpolar (poly(2-vinylpyridine) (P2VP), poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), and polystyrene (PS)), filled with three monofunctional-silane modifications of colloidal silica nanospheres (octyldimethylmethoxysilane, chloropropyldimethylethoxysilane, and aminopropyldimethylethoxysilane). We hypothesize the ratio of the work of adhesion between filler and polymer to the work of adhesion of filler to filler (WPF/WFF...
TL;DR: In this article, small-angle neutron scattering (SANS) measurements on a series of polystyrene bottlebrush polymers with varying side-chain and backbone lengths in d8-toluene were performed to analyze their size, shape and conformation.
Abstract: Bottlebrush polymers are highly branched macromolecules with potential applications in antifouling coatings, rheological modifiers, and drug delivery systems. However, the solution conformation of bottlebrush polymers has been studied in only a limited set of materials made primarily by grafting-from polymerization. Here we present small-angle neutron scattering (SANS) measurements on a series of polystyrene bottlebrush polymers with varying side-chain and backbone lengths in d8-toluene to analyze their size, shape, and conformation. Bottlebrush polymers with 2–7 kg mol–1 polystyrene side chains (degree of polymerization DP = 14–54) and poly(oxanorbornene) backbones (DP = 10–264) were synthesized using reversible addition–fragmentation chain transfer (RAFT) followed by a ring-opening metathesis polymerization (ROMP) grafting-through synthesis scheme. Analysis by Guinier–Porod, rigid cylinder, and flexible cylinder models provided estimates of the bottlebrush polymer length, radius, and stiffness. The bott...
TL;DR: It is demonstrated that vapor-induced phase separation played a pivotal role in generating the yarns with a unique structure and the low vapor pressure of N,N-dimethylformamide (DMF) was critical to the evolution of pores in the interiors.
Abstract: This article presents a simple and reliable method for generating polystyrene (PS) yarns composed of bundles of nanofibrils by using a proper combination of solvent and relative humidity. We elucidated the mechanism responsible for the formation of this new morphology by systematically investigating the molecular interactions among the polymer, solvent(s), and water vapor. We demonstrated that vapor-induced phase separation played a pivotal role in generating the yarns with a unique structure. Furthermore, we discovered that the low vapor pressure of N,N-dimethylformamide (DMF) was critical to the evolution of pores in the interiors. On the contrary, the relatively high vapor pressure of tetrahydrofuran (THF) hindered the formation of interior pores but excelled in creating a rough surface. In all cases, our results clearly indicate that the formation of either internal porosity or surface roughness required the presence of water vapor, a nonsolvent of the polymer, at a proper level of relative humidity. The exact morphology or pore structure was dependent on the speed of evaporation of the solvent(s) (DMF, THF, and their mixtures) as well as the interdiffusion and penetration of the nonsolvent (water) and solvent(s). Our findings can serve as guidelines for the preparation of fibers with desired porosity both internally and externally through electrospinning.
15 Mar 2013
TL;DR: It is found that GO coated polystyrene (PS) microspheres with narrow size distribution are obtained, although highly hydrophilic GO nanosheets cannot stabilize the monomer droplets in aqueous phase.
Abstract: Exfoliated graphene oxide (GO) nanosheets with hydrophilic oxygen-containing functional groups and hydrophobic residual conjugated structure are prepared by the oxidation of graphite powders. Polymerization of styrene stabilized by GO nanosheets is conducted at varied pH values. The morphology of the products is observed by field-emission scanning electron microscope (FE-SEM). It is found that GO coated polystyrene (PS) microspheres with narrow size distribution are obtained, although highly hydrophilic GO nanosheets cannot stabilize the monomer droplets in aqueous phase. Flocculation of polymer microspheres and GO nanosheets embedded in the PS matrix is induced by further decreasing the hydrophilicity of stabilizer. FT-IR, UV–vis spectra, XRD patterns and TGA results indicate the strong interaction between resulted PS chains and GO nanosheets during the initial stage of the polymerization. The amphiphilicity of GO nanosheets and the interaction between polymer and stabilizer are considered to be responsible for the fabrication of GO coated PS colloidal particles.
TL;DR: The particles with extremely lower density than common magnetic particles exhibited solid-like magnetorheological phase characteristics, and the flow curves were fitted to the Cho-Choi-Jhon model of the rheological equation of state.
Abstract: Core–shell-structured magnetic polystyrene (PS)/inorganic particles were fabricated by Pickering emulsion polymerization using nanosized Fe2O3 particles as a solid stabilizer. Scanning electron microscopy and transmission electron microscopy confirmed the synthesized PS/Fe2O3 particles to be comprised of a PS surface coated with Fe2O3 nanoparticles. The chemical structure of the composite nanospheres was characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The thermal properties of composite nanospheres and corresponding pure polymer were examined by thermogravimetric analysis. The rheological properties of the core–shell-structured magnetic PS/inorganic particles dispersed in silicone oil were investigated under an external magnetic field strength using a rotational rheometer. The particles with extremely lower density than common magnetic particles exhibited solid-like magnetorheological phase characteristics, and the flow curves were fitted to the Cho–Choi–Jhon model of the r...
TL;DR: In this paper, the mixtures of palm shell and polystyrene waste were pyrolyzed to obtain a high-grade of pyrotelytic liquid that potentially could be used as a fuel.
TL;DR: In this article, a novel polystyrene/n-tetradecane composite nanoencapsulated phase change material as latent functionally thermal fluid (LFTF) for cold thermal energy storage was synthesized by ultrasonic-assistant miniemulsion in situ polymerization.
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02 Mar 2013
TL;DR: Boyer et al. as discussed by the authors used differential scanning calcorimetry (DSC) to observe the Tll transition in polystyrene and showed that Tll and Related Phenomena for Local Structure in the Amorphous State of Polymers are the Manifestations of a Unique Relaxation Process.
Abstract: I: Structure and Order.- The Local Structure of Noncrystalline Polymers: An X-ray Approach.- Interrelationships Between Molecular and Physical Structure in Amorphous Polymers.- Studies on the Nature of Order in Amorphous Polymers.- Structure and Transitions in Atactic Polystyrene.- Ultraquenching, Double Tg, Order, and Motion in Amorphous Polymers.- Interim Report on the Thermoreversible Gelation of Polymers.- II: Contributions of Boyer and Colleagues.- Evidence from Tll and Related Phenomena for Local Structure in the Amorphous State of Polymers.- Techniques for Studying Liquid State Transitions in Polystyrene.- Differential Scanning Calorimetry (DSC) Observation of the Tll Transition in Polystyrene.- Hot Stage Microscopy of Polystyrene and Polystyrene Derivatives.- Dielectric Investigations of Poly(propylene oxide) in the Liquid Region Above Tg.- Pellet Boundary Reformation in Reheated Polystyrene Moldings.- III. Polymer Transition Studies.- Evidence for Transition-like Phenomena in Oligomers and Polymers Above Their Melt Temperature.- Thermally Stimulated Current Studies of Transitions in Amorphous Polymers.- Structure and Transitions Below and Above Tgin Polymers Derived from Itaconic Acid Derivatives.- Molecular Origins of Deformation Behavior and Physical Aging in Polycarbonate Copolymers.- An Analysis of Secondary Relaxations in Bisphenol-A Polysulfone.- The Tss, Tg, and Tll "Transitions": Are These the Manifestations of a Unique Relaxation Process?.- Rheological Studies of Amorphous Polymers Above Tg.- The Biaxial Squeeze-Flow Characteristics of Atactic Polystyrene Above the Glass Transition Temperature.- Frozen Energy Potential in Polymers.- IV. Discussion.- Panel Discussion.- Participants.- Name Index.
TL;DR: In this article, surface modified TiO2 nanoparticles were added to a mixture of polystyrene-block-poly(ethylene oxide) and bis(trifluoromethane)sulfonimide lithium salt.
Abstract: There is considerable interest in developing solid electrolytes for rechargeable lithium batteries as they have the potential to increase both energy density due to incorporation of a lithium metal anode and safety of batteries due to the fact that they are nonflammable. Block copolymers with a mechanically hard non-conducting block and a soft ion-conducting block provide an avenue for obtaining highly conducting rigid solids. In this study we add surface-modified TiO2 nanoparticles to a mixture of polystyrene-block-poly(ethylene oxide) and bis(trifluoromethane)sulfonimide lithium salt. The presence of BF4 − moieties on the surface of the particles was essential for obtaining macroscopically homogeneous electrolytes; macrophase separation was observed with the same nanoparticles with surfaces covered with oleic acid. The stability of these composite electrolytes against lithium metal electrodes was tested in symmetric lithium-composite electrolyte-lithium cells. The surprising result was that electrolytes with 24 wt% nanoparticles exhibited optimum stability; the amount of charge passed before dendrite formation observed in the optimized composite electrolyte was a factor of 4.7 larger than that of the neat block copolymer electrolyte. Both tensile and shear moduli of the electrolytes were non-monotonic functions of particle concentration with peaks in the vicinity of 17 to 20 wt%.
TL;DR: The approach provides a method for generating both aluminum oxide patterns and their corresponding inverses using the same block copolymer template, resulting in an increased Lewis base-acid interaction with the organometallic precursors.
Abstract: We report chemical modification of self-assembled block copolymer thin films by ultraviolet light that enhances the block-selective affinity of organometallic precursors otherwise lacking preference for either copolymer block. Sequential precursor loading and reaction facilitate formation of zinc oxide, titanium dioxide, and aluminum oxide nanostructures within the polystyrene domains of both lamellar- and cylindrical-phase modified polystyrene-block-poly(methyl methacrylate) thin film templates. Near-edge X-ray absorption fine structure measurements and Fourier transform infrared spectroscopy show that photo-oxidation by ultraviolet light creates Lewis basic groups within polystyrene, resulting in an increased Lewis base–acid interaction with the organometallic precursors. The approach provides a method for generating both aluminum oxide patterns and their corresponding inverses using the same block copolymer template.
TL;DR: In this article, the structural features of polystyrene brushes grafted on spherical silica nanoparticles are investigated by means of a Monte Carlo methodology based on polymer mean field theory.
Abstract: The structural features of polystyrene brushes grafted on spherical silica nanoparticles immersed in polystyrene are investigated by means of a Monte Carlo methodology based on polymer mean field theory. The nanoparticle radii (either 8 or 13 nm) are held constant, while the grafting density and the lengths of grafted and matrix chains are varied systematically in a series of simulations. The primary objective of this work is to simulate realistic nanocomposite systems of specific chemistry at experimentally accessible length scales and study the structure and scaling of the grafted brush. The profiles of polymer density around the particles are examined; based on them, the brush thickness of grafted chains is estimated and its scaling behavior is compared against theoretical models and experimental findings. Then, neutron scattering spectra are predicted both from single grafted chains and from the entire grafted corona. It is found that increasing both the grafting density and the grafted chain molar ma...
TL;DR: In this paper, a facile and general method to covalently functionalize graphene oxide (GO) with copolymers, using poly(styrene-co-methylmethacrylate) (P(St-Co-MMA)) as an example, via miniemulsion polymerization is described.
TL;DR: Experiments with ketoprofen suggest that polystyrene anion exchange resins can be used to selectively remove other acidic pharmaceuticals from urine, and the greater regeneration efficiency of the NaCl/methanol-water mixture over the aqueous NaCl solution supports the importance of non-electrostatic interactions between resin matrix and benzene rings of diclofenac.
TL;DR: In this paper, a low-temperature processed, hydroxyl-free poly(vinyl phenyl) (PVP) dielectric layer cross-linked using thiol-ene chemistry was reported.
Abstract: We report a low-temperature processed, hydroxyl-free poly(vinyl phenyl) (PVP) dielectric layer cross-linked using thiol–ene chemistry. This new dielectric material exhibited a high dielectric constant as compared to conventional hydroxyl-free polymer dielectrics, e.g. polystyrene, and allowed for cross-linking at 80 °C, which is lower than the glass transition temperature of most commonly used plastic substrates, e.g. poly(ethylene terathalate) (PET). Due to the absence of hydroxyl groups, the dielectric layer displayed more stable performance than other previously reported cross-linked PVP dielectrics. The low-temperature processing, high air stability, and low current–voltage hysteresis while retaining high device performances are important advantages of this new dielectric material.
TL;DR: Keep your wine chilled!
Abstract: Keep your wine chilled! Microscale polystyrene (PS) bottles are loaded with dye molecules and then corked with a phase-change material (PCM). When the temperature is raised beyond its melting point, the PCM quickly melts and triggers an instant release of the encapsulated dye. The release profiles can be manipulated by using a binary mixture of PCMs with different melting points.
TL;DR: In this article, a method for the preparation of well-defined poly(styrene-b-butadiene) (PS-PB)n multiblock copolymers using a combination of living anionic polymerization and urethane based polycondensation along with an assessment of the associated microphase morphology and thermal and mechanical properties is reported.
Abstract: We report a synthetic method for the preparation of well-defined poly(styrene-b-butadiene) (PS-PB)n multiblock copolymers using a combination of living anionic polymerization and urethane based polycondensation along with an assessment of the associated microphase morphology and thermal and mechanical properties. The prepolymers, α,ω-dihydroxy polystyrene (HO-PS-OH) and α,ω-dihydroxy polybutadiene (HO-PB-OH), were prepared using a protected initiator, followed by deprotection and condensation with isophorone diisocyanate (IPDI) leading to the (PS-PB)n multiblock copolymers. Two types of block sequences were generated, one with random block sequences (PS-ran-PB)n and the second with alternating (PS-alt-PB)n block architectures. Size exclusion chromatography (SEC), 1H nuclear magnetic resonance (NMR), and Fourier transform infrared spectrometry (FTIR) confirmed that the synthetic procedures yielded the desired products. Differential scanning calorimetry (DSC) revealed microphase separation and small-angle X...
TL;DR: In this article, an oligoaniline-capped polystyrene was prepared by a copper-catalyzed click reaction between azide capped poly styrene and an alkyne-containing aniline trimer, which was doped by different acids.
Abstract: We report a simple and low-cost strategy to enhance the dielectric permittivity of polystyrene by up to an order of magnitude via incorporating an oligoaniline trimer moiety at the end of the polymer chains. The oligoaniline-capped polystyrene was prepared by a copper-catalyzed click reaction between azide-capped polystyrene and an alkyne-containing aniline trimer, which was doped by different acids. By controlling molecular weight of polystyrene, the end-capped polymers can be induced to form nanoscale oligoaniline-rich domains embedded in an insulating matrix. Under an external electric field, this led to an increase in dielectric polarizability while maintaining a low dielectric loss. At frequencies as high as 0.1 MHz, the dielectric permittivity and dielectric loss (tan δ) were ∼22.8 and ∼0.02, respectively. This strategy may open a new avenue to increasing the dielectric permittivity of many other commodity polymers while maintaining relatively low dielectric loss.
TL;DR: In this paper, a flexible superhydrophobic and superoleophilic SiO 2 /polystyrene nanocomposite coating was fabricated on fabric or filter paper surface by a one-step dipping process.