Poly Polystyrene Research Articles

Effect of Molecular Weight on Phase Equilibrium in the Polystyrene-Poly(methyl methacrylate) System.

Data on the solubility of oligomer polystyrene (PS) and poly(methyl methacrylate) (PMMA) of various molecular weights have been obtained. The binodal and spinodal curves of the phase state diagram with the upper critical solution temperature (UCST) are constructed through simulation within the framework of the Flory-Huggins theory. The influence of the molecular weight of polymers on the contribution to their mixing has been compared, and correlation curves have been plotted. The interaction parameters were calculated and the mixing thermodynamics of the components was evaluated. The largest contribution was made by the entropy component. Also, it has been shown using IR spectroscopy that there is no interaction between the functional groups of polystyrene and poly(methyl methacrylate) in a homogeneous mixture.

Morphology-Controlled Mesopores with Hydrophilic Pore Walls from Triblock Copolymers

We report a facile approach that can simultaneously control the morphology and surface chemistry of mesoporous materials from triblock copolymers. By doping phosphotungstic acid (PW), the self-assembled structures of polystyrene–poly(ethylene oxide)–polylactide (PS–PEO–PLA, SEL) triblock copolymer can be tuned. Besides core–shell cylinders and lamellae, disordered bicontinuous structures can be achieved in SEL/PW composites. After etching with NaOH, PLA domains and PW additive are removed simultaneously, giving mesoporous PS monoliths with controlled morphologies and PEO-coated pores. Also, we demonstrated that the prepared porous PS monoliths can be used as templates to fabricate inorganic nanostructures. This work provides new insight into the fabrication of functional mesoporous materials.

Complex viscosity of poly[n]catenanes including olympiadanes

Chains of mechanically interlocking or intersecting organic rings, called poly[n]catenanes, afford interesting opportunities to study the role of orientation in suspensions. We call poly[5]catenanes olympiadanes. In this work, we use general rigid bead-rod theory to arrive at general expressions, from first principles, for the complex viscosity of poly[n]catenane suspensions. General rigid bead-rod theory relies entirely on suspension orientation to explain the elasticity of the liquid. We obtain analytical expressions for the complex viscosity of poly[n]catenanes for both n even and odd, for both mechanically interlocking and intersecting rings, and for identically sized rings. We restrict our analysis to evenly spaced poly[n]catenanes of orthogonal adjacency. We find that the parts of the complex viscosity for intersecting and interlocking rings, when made dimensionless with the polymer contribution to the zero-shear viscosity, match. We find good agreement with the available complex viscosity measurements for molten intersecting polystyrene poly[1,3]catenanes, but not so for poly[2]catenanes. We next calculate space filling equilibrium structures of these poly[1–3]catenanes, only to discover that each polystyrene ring looks more like a bead. We find that, for these polystyrene poly[n]catenanes and for good agreement with the available complex viscosity measurements, the shish-kebab theory suffices.

Cyanide-Free Cyanation of Aryl Iodides with Nitromethane by Using an Amphiphilic Polymer-Supported Palladium Catalyst

AbstractA cyanide-free aromatic cyanation was developed that uses nitromethane as a cyanide source in water with an amphiphilic polystyrene–poly(ethylene glycol) resin-supported palladium catalyst and an alkyl halide (1-iodobutane). The cyanation proceeds through the palladium-catalyzed cross-coupling of an aryl halide with nitromethane, followed by transformation of the resultant (nitromethyl)arene intermediate into a nitrile by 1-iodobutane.

Self-organization of random copolymers to nanopatterns by localized e-beam dosing

Strategic electron beam (e-beam) irradiation on the surface of an ultrathin (<100 nm) film of polystyrene–poly(methyl methacrylate) (PS-PMMA) random copolymer followed by solvent annealing stimulates a special variety of dewetting, leading to large-area hierarchical nanoscale patterns. For this purpose, initially, a negative (positive) tone of resist PS (PMMA) under weak e-beam exposure is exploited to produce an array of sites composed of cross-linked PS (chain-scissioned PMMA). Subsequently, annealing with the help of a developer solvent engenders dewetted patterns in the exposed zones where PMMA blocks are confined by the blocks of cross-linked PS. The e-beam dosage was systematically varied from 180 μC cm−2 to 10 000 μC cm−2 to explore the tone reversal behavior of PMMA on the dewetted patterns. Remarkably, at relatively higher e-beam dosing, both PMMA and PS blocks act as negative tones in the exposed zone. In contrast, the chain scission of PMMA in the periphery of the exposed regions due to scattered secondary electrons caused confined dewetting upon solvent annealing. Such occurrences eventually lead to pattern miniaturization an order of magnitude greater than with conventional thermal or solvent vapor annealed dewetting. Selective removal of PMMA blocks of RCP using a suitable solvent provided an additional 50% reduction in the size of the dewetted features.

Amphiphilic Immobilized Diphenylprolinol Alkyl Ether Catalyst on PS-PEG Resin

Abstract Diphenylprolinol silyl ether is a widely used organocatalyst, and its immobilization on a solid support was investigated for the easy recycling and reuse of this catalyst. Because a silyl ether bond of the catalyst is weak, its alkyl ether was attached to polymers such as a polyquinoxaline-based polymer, a polystyrene polymer (PS) resin, and a polystyrene–poly(ethylene glycol) graft copolymer (PS-PEG) resin. Although a polymer-supported organocatalyst generally decreases its reactivity compared with the monomer catalyst, diphenylprolinol anthrylmethyl ether supported on PS-PEG was found to be a reactive organocatalyst; it catalyzed the Michael reaction of an aldehyde and a nitroalkene in water without an organic solvent being present, with excellent diastereo- and enantioselectivities.

Quantifying separation energy with a modified Capillary Break-up Extensional Rheometer (CaBER) to study polymer solutions

ABSTRACT A Capillary Break-up Extensional Rheometer (CaBER) was modified to enable measurements of the axial force in combination with the related displacement. This makes it possible to determine the separation energy , the tackiness, of a polymer solution between two parallel plates with the CaBER. Separation energies of solutions of linear polystyrene, comb polystyrene and linear poly(methyl methacrylate) in dimethylformamide were measured as model systems. For linear polymers at a critical polymer concentration, there was a drastic change in slope of the separation energy . This critical concentration was shown to be the minimum concentration at which continuous bead-free fibers could be electrospun.

Determination of Binary Interaction Parameters for Ternary Polymer–Polymer–Solvent Systems Using Raman Spectroscopy

AbstractMultilayer coatings and drying of polymer films are widely used to produce different applications like organic electronics or barrier foils. If the product quality requires separated layers, partial or immiscible systems can be used to avoid interdiffusion between the layers. For the prediction of a possible phase separation of a ternary polymer–polymer–solvent system, it is required to measure or obtain from a data bank the three binary interaction parameters of the system to describe its thermodynamic behavior. This poses a challenge due to the scarce data and measurement techniques for polymer–solvent interaction parameters, but even more for polymer–polymer interaction parameters. In this work, a numerical routine is developed to predict the phase separation for given interaction parameters and is validated with literature results. Subsequently, different ternary polystyrene–poly(methyl methacrylate)–toluene mixtures are prepared and the resulting composition of the phase (or phases) is measured via Raman spectroscopy. The determined equilibrium data are used to fit the binary interaction parameters, which can be used afterward as input parameters for the numerical routine in order to predict the ternary phase diagram of the system.

Magnetic Field Implementing into the Electroluminescence of OLED Devices Doped with CoFe2O4 Nanoparticles

Cobalt ferrite magnetic nanoparticles (CoFe2O4 MNPs) were successfully prepared by citric acid-assisted sol-gel auto combustion method and used in emissive layer of organic light emitting diode (OLED). Dimensional, structural and magnetic properties of CoFe2O4 nanoparticles (NPs) were recearched and compared by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). CoFe2O4 MNPs were utilized at various concentrations (0.5 wt%, 1.0 wt% and 2.0 wt%) in the emissive layer of the OLEDs. The luminance, current efficiency and the electroluminescence characteristics of the devices with and without CoFe2O4 MNPs were investigated. An external magnetic field, Bext, has also been applied to the OLEDs doped with MNPs while under operation. Effects of MNPs on OLED characteristics under Bext were studied thoroughly. In the tailored device architecture, poly (3,4-ethylenedioxythiophene): poly polystyrene sulphonate (PEDOT: PSS) and poly(2-methoxy-5-(2-ethylhexyloxy))-1,4-phenylene vinylene (MEH-PPV) were used as a hole transport layer (HTL) and an emissive layer respectively with ITO/PEDOT: PSS/ MEH-PPV: CoFe2O4/Ca/Al device architecture. The obtained results of the fabricated OLEDs were enhanced in the presence of CoFe2O4 NPs under Bext due to providing density of states in the polymer matrices. The turn-on voltage was diminished slightly in the device doped with 0.5 % wt MNP compared to the devices with other concentrations of MNPs.

Multicompartmental Mesoporous Silica/Polymer Nanostructured Hybrids: Design Capabilities by Integrating Linear and Star-Shaped Block Copolymers.

Poly(2-vinyl pyridine)-b-poly(ethylene oxide) (P2VP-b-PEO) linear diblock copolymer and polystyrene–poly(ethylene oxide) (PS10PEO10) heteroarm star copolymer were used as building elements to prepare organic–inorganic hybrids. By using the layer-by-layer (LbL) methodology, these elements were integrated on mesoporous silica through non-covalent interactions, namely, ionic and H-bonding. For the latter, tannic acid (TA) was used as an intermediate layer. The deposition of the various layers was monitored by thermogravimetric analysis (TGA), electrophoretic measurements, and confocal microscopy. The final silica hybrid, bearing alternating P2VP-b-PEO and PS10PEO10 star layers was capable of carrying one hydrophilic and two hydrophobic chemical species in distinct compartments. These multicompartmental organic–inorganic hybrids could be used as nanostructured carriers for pH-responsive multiple drug delivery and potential theranostic applications.

Photocontrol of Supramolecular Azo-Containing Block Copolymer Thin Films during Dip-Coating: Toward Nanoscale Patterned Coatings

Dip-coating allows nanostructured block copolymer (BCP) thin film fabrication in a fast and facile one-step process. It can also be coupled with external controls, such as illumination. Herein, we expose several design principles that enable photocontrol of the nanostructured surface pattern and thickness of supramolecular BCP thin films. This is done using a polystyrene–poly(4-vinylpyridine) (PS-P4VP) BCP and two hydroxy-functionalized small-molecule (SM) azo derivatives that have different photochemical characteristics and that hydrogen bond to the P4VP block. We show how the film preparation concept provides tunability through the chemical structure of the photoactive SM, the relative amount of SM in the dip-coating solution, and the choice of solvent. It was found that the film thickness and SM uptake in the films are increased by illumination when THF is used but are unchanged when toluene is used as solvent, which is attributed to an optical heating effect observable with volatile solvents. The phot...

Solvent-Free A3 and KA2 Coupling Reactions with mol ppm Level Loadings of a Polymer-Supported Copper(II)–Bipyridine Complex for Green Synthesis of Propargylamines

A copper(II)–bipyridine complex immobilized on amphiphilic polystyrene–poly(ethylene glycol) (PS–PEG) resin (PS–PEG-BPy–CuBr2) has been developed. The immobilized copper(II)–bipyridine complex at a mol ppm level of loading efficiently catalyzed the three-component coupling of aldehydes or ketones, amines, and alkynes (A3 or KA2 coupling) under solvent-free conditions to give the corresponding propargylamines in good-to-excellent yields. Moreover, 10 g-scale green syntheses of propargylamines proceeded with excellent atom economy (E factor ≥ 0.38) through a solvent-free A3 coupling using 5 mol ppm of PS–PEG-BPy–CuBr2. The total turnover number and turnover frequency of the catalyst reached as high as 178 800 and 7450 h–1, respectively.

Iterative Preparation of Platinum Nanoparticles in an Amphiphilic Polymer Matrix: Regulation of Catalytic Activity in Hydrogenation

We demonstrate that iteration of the seeded preparation of platinum nanoparticles dispersed in an amphiphilic polystyrene–poly(ethylene glycol) resin (ARP–Pt) regulates their catalytic activity in the hydrogenation of aromatic compounds in water. The catalytic activity of the fifth generation of ARP–Pt [G5] prepared through four iterations of the seeded preparation was far superior to that of the initial ARP–Pt [G1] in the hydrogenation of aromatic compounds in water.

Aqueous Flow Hydroxycarbonylation of Aryl Halides Catalyzed by an Amphiphilic Polymer-Supported Palladium–Diphenylphosphine Catalyst

An aqueous continuous-flow reaction system is developed for the palladium-catalyzed hydroxycarbonylation of aryl halides. Flow hydroxycarbonylation of aryl halides in aqueous solution proceeds efficiently in a flow reactor containing a palladium–diphenylphosphine complex immobilized on an amphiphilic polystyrene–poly(ethylene glycol) resin to give the corresponding benzoic acids in excellent yields.

Evolution of Microstructure in Block Copolymer Thin Films during Zone Annealing

The effect of zone annealing on a microstructure from horizontal and vertical cylinders in the microphase-separated films of polystyrene–polybutadiene–polystyrene triblock copolymer and polystyrene–poly(4-vinylpyridine) diblock copolymer is studied. It is shown that processing of the films of different thicknesses at various maximum thermal front temperatures which do not exceed the temperature of orderdisorder transition does not lead to a noticeable increase in their degree of ordering. On the contrary, once the transition temperature is approached, the interfacial area between domains formed by different types of blocks is increased and the order in their arrangement disappears, with the thermal stability of the structure falling with an increase in film thickness. Thus, the substantial microstructure ordering during the cold zone annealing of the polystyrene–poly(methyl methacrylate) diblock copolymer described in the literature has not yet been reproduced for other systems. The maximum rate of gradient zone motion at which this effect is to be expected is estimated.

Colloid silica nanoparticles trapped morphology of polymer blends during solvent evaporation

During the solvent evaporation induced phase separation of PS and PMMA blends with silica nanoparticles, the dispersed and bicontinuous morphologies need to be stabilized by the absorption of silica nanoparticles at the interface. In order to accomplish this, the silica nanoparticles need to be chemically neutral to PS and PMMA homopolymers. For this purpose, their surfaces were modified by attaching mono-hydroxyl group terminated polystyrene poly(methyl methacrylate) random (PS-r-PMMA-OH) copolymer via the condensation reaction between the hydroxyl groups of silica particles and copolymer. The resulting morphology was found to be affected by the rate of solvent evaporation, blend compositions, particle loading and size. In the symmetric blend system, the dispersed phase was observed at low evaporation rate and bicontinuous morphology was obtained at high evaporation rate. The silica nanoparticles were found to be densely packed at the interface of PS and PMMA. For asymmetric blend system, only dispersed phase was observed at both low and high evaporation rates. The size of phase separated domains decreases with increasing solvent evaporation rate and particle loading. The silica nanoparticles with smaller size resulted in relatively smaller domain size due to their higher surface area to volume ratio. Porous membranes with partially exposed nanoparticles were fabricated by etching PMMA phase in acetic acid.

Atomistic Molecular Dynamics Simulations of Polymer/Graphene Nanostructured Systems

Graphene based polymer nanostructured systems are hybrid materials with a broad range of technological applications. Here, we present results from detailed all-atom simulations of various polymer/graphene model systems. Different polymers are studied: Polyethylene (PE), Polystyrene (PS,) Poly(methyl methacrylate) (PMMA) and Poly(ethylene oxide) (PEO) as thin films either confined between two graphene layers or as free standing polymer films supported by multiple graphene layers. Moreover, we study graphene based polymer nanocomposites. We present a detailed analysis of the structural and dynamical heterogeneities of the hybrid model systems, through all-atom Molecular Dynamics simulations. Both structural and dynamical properties of the hybrid systems are studied and compared with the corresponding properties of the bulk systems respectively. Equilibrium and non-equilibrium phenomena of hybrid polymeric systems are analyzed over a broad range of time and length scales.

Preparation of Aryl(dicyclohexyl)phosphines by C–P Bond-Forming Cross-Coupling in Water Catalyzed by an Amphiphilic-Resin-Supported Palladium Complex

Aryl(dicyclohexyl)phosphines were prepared by a catalytic C–P bond-forming cross-coupling reaction of haloarenes with dicyclohexylphosphine under heterogeneous conditions in water containing an immobilized palladium complex coordinated to an amphiphilic polystyrene–poly(ethylene glycol) resin supported di(tert-butyl)phosphine ligand.

Synthesis and gas transport properties of polypentafluorostyrene

Polypentafluorostyrene (PPFS) (M w = 1.7 × 105 Da, M w /M n = 1.6, and Т g = 110°С) has been synthesized by radical polymerization of pentafluorostyrene. The chemical structure of the polymer has been confirmed by 1H and 19F NMR data. The permeability and diffusion coefficients of gases (He, H2, O2, N2, CO2, and CH4) have been measured on a barometric setup. The permeability, diffusion, and solubility coefficients of gases have been shown to increase with the increases in the fluorine content in the repeat unit of the polymer in the polystyrene–poly(p-fluorostyrene)–PPFS series. Such behavior of transport parameters in the polymer series is associated with the growth in the fractional free volume and decrease in the cohesive energy density. The investigated polymers on the basis of styrene and its derivatives including PPFS are located in the middle of clouds of Robeson diagrams for N2/CH4, CO2/CH4, and O2/N2 and are not of interest for their separation.

Batch and Continuous-Flow Huisgen 1,3-Dipolar Cycloadditions with an Amphiphilic Resin-Supported Triazine-Based Polyethyleneamine Dendrimer Copper Catalyst

A polystyrene–poly(ethylene glycol) (PS–PEG) resin-supported triazine-based polyethyleneamine dendrimer copper catalyst (PS–PEG-TD2–CuSO4) was prepared and characterized by means of CP-MAS NMR, UV–vis/NIR, FTIR, SEM-EDX, XPS, and ICP-AES analyses. PS–PEG-TD2–CuSO4 was highly active in the Huisgen 1,3-dipolar cycloaddition of various organic azides with alkynes in water as well as the three-component reaction of alkynes, alkyl bromides, and sodium azide under batch conditions to give the corresponding triazoles in excellent yields with high recyclability of the catalyst. TEM analysis suggested that the copper nanoparticles generated in situ through reduction of PS–PEG-TD2–CuSO4 with sodium ascorbate serve as the active catalytic species. The application of PS–PEG-TD2–CuSO4 catalyst in a continuous-flow Huisgen reaction for the synthesis of 1,2,3-triazoles was also examined. The cycloaddition of organic azides with alkynes was completed within 22 s in the continuous-flow system containing PS–PEG-TD2–CuSO4 t...