Showing papers on "Polystyrene published in 1998"
TL;DR: It is believed that it is possible to control the composite particle size and morphology by a convenient choice of the composition of the system, and this new polymer-encapsulation process could be used to synthesize other organic-inorganic composite particles, using, for example, other monomers or minerals.
451 citations
TL;DR: In this article, the morphological development in solvent-cast polystyrene thin films is described as a function of solvent evaporation, and a morphological morphological model for polybutadiene (PB) is proposed.
Abstract: This paper describes morphological development in solvent-cast polystyrene (PS)−polybutadiene (PB)−polystyrene (SBS) triblock copolymer thin films (30 wt % PS) as a function of solvent evaporation ...
432 citations
TL;DR: A novel octafunctional calixarene derivative, namely, 5,11,17,23,29,35,41,47-octa-tertbutyl-49,50,51,52,53,54,55,56-octakis(2-bromopropionyloxy)calix[8]arene (1) which was readily synthesized in one step, was used to initiate the bulk atom transfer radical polymerization (ATRP) of styrene, at 100 °C, in the presence of CuBr/
Abstract: A novel octafunctional calixarene derivative, namely, 5,11,17,23,29,35,41,47-octa-tert-butyl-49,50,51,52,53,54,55,56-octakis(2-bromopropionyloxy)calix[8]arene (1) which was readily synthesized in one step, was used to initiate the bulk atom transfer radical polymerization (ATRP) of styrene, at 100 °C, in the presence of CuBr/2,2‘-bipyridyl. Polystyrene (PS) stars of narrow polydispersity with precisely eight arms could be synthesized by restricting the polymerization to low conversion, typically below 15−20%. At higher conversions, irreversible coupling occurred between stars as evidenced by a size exclusion chromatography line equipped with a multiangle laser light scattering detector (MALLS/SEC). Octafunctional stars of molar masses up to 340 000 g mol-1 could be prepared by using high ratios of the monomer to the initiator ([M]/[I] = 12 000). The precise octafunctional structure of the stars was confirmed, on one hand, by studying the kinetics of ATRP of styrene initiated by an equimolar mixture of 1 a...
310 citations
TL;DR: In this article, a novel concept for the generation of molecularly thin polymer layers attached to a solid surface is described, where functional groups of the polymers are reacted with appropriate sites on the surfaces of a substrate the polymer layers are formed in situ by using self-assembled monolayers of an initiator.
Abstract: A novel concept for the generation of molecularly thin polymer layers attached to a solid surface is described. In contrast to commonly used techniques, where functional groups of the polymers are reacted with appropriate sites on the surfaces of a substrate the polymer layers are formed in situ by using self-assembled monolayers of an initiator. As an example, the formation of polystyrene monolayers terminally attached to silicon oxide surfaces through radical chain polymerization which has been started by a self-assembled monolayer of an azo initiator is described. The thickness of the attached polymer films can be adjusted over a wide range up to values of several hundred nanometers by variation of polymerization parameters such as temperature and azo conversion. When suitable conditions are chosen, monolayers with thicknesses inaccessible by other techniques of preparation can be obtained.
287 citations
TL;DR: In this article, carbon black (CB) particles are selectively localized at the interface of polyethylene/polystyrene (PE/PS) blends used as models of two-phase polyblends.
Abstract: Several strategies are reported that allow carbon black (CB) particles to be selectively localized at the interface of polyethylene/polystyrene (PE/PS) blends used as models of two-phase polyblends. A first general approach relies upon a kinetic control, i.e., the choice of such processing conditions that the CB particles are “immobilized” at the polyblend interface at least for a workable period of time. The dry premixing of the two powdery polymers and CB particles followed by compression molding is the first valuable kinetic control. A second one can be implemented during the melt blending of the immiscible polymers, which makes this strategy more attractive. Actually, CB is first dispersed in the melted polymer with which it less strongly interacts. Upon the addition and melting of the second polymer, CB particles are thermodynamically driven to this second polymer phase. The conducting particles are observed to accumulate at the polyblend interface at a rate and for a period of time that depend on th...
257 citations
TL;DR: In this paper, a simple subtraction process was adopted to highlight the changes occurring in the valence band spectra upon treatment of polystyrene (PS) and polypropylene (PP).
Abstract: Argon plasma treatment and subsequent atmospheric exposure have been used to incorporate new oxygen functionalities at the surface of polystyrene (PS) and polypropylene (PP). High-energy resolution X-ray photoelectron spectroscopy (XPS) has yielded molecular information regarding the site of modification in both polymers. Core level and valence band spectra have been interpreted. We have adopted a simple subtraction process to highlight the changes occurring in the valence band spectra upon treatment. In the case of PS, modification is found to be occurring at ring sites. In PP, modification is thought to be occurring at two sites. We propose that modification at the tertiary carbon site leads to chain scission and subsequent etching, while modification at the methyl side group results in functionalities being incorporated at the polymer surface. These data help to substantiate mechanisms that were previously proposed, based on the accepted mechanisms of cross-linking vs chain scission for these polymers.
233 citations
TL;DR: Tempering of polystyrene films containing the novel liquid crystalline coronenebis(dicarboximide)s 2, which are formed by an easy route from perylene-3,4;9,10-tetracarboxylic dianhydride, leads to a shift of the emission within a few seconds, which could be used for dot-by-dot coloring and thus optical displays.
Abstract: Tempering of polystyrene films containing the novel liquid crystalline coronenebis(dicarboximide)s 2, which are formed by an easy route from perylene-3,4;9,10-tetracarboxylic dianhydride (1), leads to a shift of the emission within a few seconds. This could be used for dot-by-dot coloring and thus optical displays. The photoluminescence properties of 2 in the solid matrix are dependent on the nature of the aggregates formed.
185 citations
TL;DR: In this paper, the structural affinity between styrene monomer and the organic group of org-MMT plays an important role in the structure and properties of hybrid materials, and the resulting materials showed an expansion of interlayer distance.
Abstract: Styrene monomer was mixed with quaternary ammonium montmorillonites(org-MMTs) and polymerized in the presence of radical initiator. The resulting materials showed an expansion of interlayer distance. These hybrid materials exhibited higher thermal stability compared with the virgin polystyrene(PS) or PS/pristine-MMT microcomposite. PS/Bz-MMT, containing benzyl-unit similar to styrene in org-MMT, exhibited higher decomposition temperature even for MMT loading as low as 0.3wt.% compared with other PS/org-MMT hybrids. It was found that the structural affinity between styrene monomer and the organic group of org-MMT plays an important role in the structure and the properties of hybrid materials.
184 citations
TL;DR: The potential of polystyrene beads as a simple alternative to other conventional detergent removing strategies such as dialysis, gel chromatography and dilution is established and the usefulness of this detergent removal strategy to produce quasi-ideal proteoliposomes is evaluated.
Abstract: Detergent removal from lipid-protein-detergent micellar solutions is the most successful strategy for reconstitution of integral membrane proteins into proteoliposomes or into two-dimensional crystals. This review establishes the potential of polystyrene beads as a simple alternative to other conventional detergent removing strategies such as dialysis, gel chromatography and dilution. Kinetics and equilibrium aspects of removal of different detergents by hydrophobic adsorption onto polystyrene beads have been systematically investigated. A mechanism of adsorption onto polystyrene beads is proposed and provide useful information about the use of these beads in reconstitution experiments. The usefulness of this detergent removal strategy to produce quasi-ideal proteoliposomes is evaluated by considering the morphology and the size of the reconstituted vesicles, the homogeneity in size and protein distribution, the final protein orientation and the permeability of resulting proteoliposomes. Finally, the advantages of detergent removal by polystyrene beads as an alternative to conventional dialysis in two-dimensional crystallization trials are evaluated through review of recent structural reconstitution studies.
181 citations
TL;DR: In this article, some mechanistic models for polymerization and stereo-regulation as well as the factors which affect the activity and stereospecificity of the catalysts are discussed, and the effects of substitutions on Cp ligand of half titanocene complexes were examined.
Abstract: Syndiotactic polystyrene, namely XAREC® is being developed by Idemitsu Petrochemical Co., Ltd. as a major new polymer family. XAREC® is a new crystalline engineering thermoplastic with a crystalline melting point of 270 °C. Because of its crystalline nature, XAREC® has a high heat resistance, an excellent chemical resistance and a water/steam resistance. XAREC® also has the dip soldering resistance. Potential applications for XAREC® include surface-mount electronic devices and electrical connectors. In this paper, some mechanistic models for polymerization and stereo-regulation as well as the factors which affect the activity and stereospecificity of the catalysts are discussed. The effects of substitutions on Cp ligand of half titanocene complexes were examined. The bulky substitution groups reduce the activity. Also, borate compounds as activator and effects of hydrogen are discussed.
171 citations
Abstract: Poly(N-vinylpyrrolidone)-stabilized polystyrene (PS) latexes have been coated with thin overlayers of polyaniline (PANi) to produce electrically conductive “core−shell” particles. In this work we focused on the morphology of the PANi overlayer, the colloid stability of the coated latexes, and electrical conductivity. PANi-coated particles exhibit a nonuniform morphology as observed by scanning electron microscopy (SEM), in comparison with the relatively smooth polypyrrole overlayers synthesized in a previous study (Lascelles, S. F. et al., J. Mater. Chem. 1997, 7, 1339 and 1349). Disk centrifuge photosedimentometry confirmed that the PANi-coated PS latexes were weakly flocculated. The underlying PS latex “core” was quantitatively removed by solvent extraction, and SEM observations of the PANi residues revealed a “broken egg shell” morphology. Vibrational bands due to the PANi component were more intense in both the FT-IR and Raman spectra of the PANi-coated PS latexes, which is also consistent with the “c...
TL;DR: In this article, a triblock copolymer is synthesized by using a strategy in which the α-coupling of 11 thiophene rings of the middle block and the monodispersity (DP = 30 and Mw/Mn = 1.1) of the two polystyrene outer blocks is ensured.
Abstract: A well-defined triblock copolymer is synthesized by using a strategy in which the α-coupling of 11 thiophene rings of the middle block and the monodispersity (DP = 30 and Mw/Mn = 1.1) of the two polystyrene outer blocks is ensured. Monofunctional polystyrene 1 is first modified with an α-terthiophene unit 2 to form 3, and two of these units are coupled in a double Stetter reaction of 4 with a difunctional α-terthiophene 5 to yield a tetraketone 6 as the precursor of the triblock copolymer, which was formed with excess Lawesson's reagent. The polymer 7 is fully characterized with IR and NMR spectroscopy and MALDI-TOF mass spectrometry. Size exclusion chromatography, transmission electron microscopy, and scanning force microscopy show that 7 is self-assembled into spherical, micellar structures with average diameters of 12 nm, which corresponds to about 60 block copolymer molecules per aggregate. The optical properties of 7 are in full agreement with an associated unsubstituted oligothiophene. Electrochem...
TL;DR: Styrolux and Styroflex are block copolymers prepared by butyllithium initiated anionic polymerization as discussed by the authors, which is a transparent, tough and stiff thermoplastic material for high speed processing.
Abstract: Styrolux and Styroflex are styrene and butadiene based block copolymers prepared by butyllithium initiated anionic polymerization. Styrolux is a transparent, tough and stiff thermoplastic material for high speed processing. Its specially designed molecular structure allows homogeneous mixing with general purpose polystyrene maintaining the transparency. Styroflex is a newly commercialized product with the mechanical behavior of a thermoplastic elastomer, e.g. low modulus and yield strength, high elongation and excellent recovery. High transparency and thermal stability give the competitive edge over conventional styrene-butadiene elastomers. Styroflex, Styrolux and general purpose polystyrene form a unit construction system e.g. for transparent film materials and injection molded parts with fine-tunable hardness and toughness.
TL;DR: In this article, the authors investigated the depletion force acting on a large colloidal polystyrene sphere immersed in a solution of small, noncharged polymer coils close to a flat glass surface by means of total internal reflection microscopy.
Abstract: In colloidal suspensions containing a binary mixture of hard spheres depletion forces occur which substantially contribute to the interaction of the larger spheres among themselves and a wall, respectively. We investigated the depletion force acting on a large colloidal polystyrene sphere immersed in a solution of small, noncharged polymer coils close to a flat glass surface by means of total internal reflection microscopy. When the distance between the polystyrene sphere and the wall is smaller than the diameter of the polymer coils, an attractive potential acting on the sphere is observed which depends strongly on the polymer concentration. Our results are in agreement with theoretical predictions.
TL;DR: This paper presents a meta-analyses of the response of the immune system to E. coli A. whitesides using a probabilistic approach and shows clear patterns in response to the presence of E. whiteside.
Abstract: The phase separation of ultrathin polymer-blend films of polystyrene and polybutadiene on microcontact printed alkanethiol patterns with hydrophobic and hydrophilic end groups $(\ensuremath{-}{\mathrm{CH}}_{3}$ and -COOH) is investigated by atomic force microscopy. Simulations suggest that the phase-separation morphology can be controlled through patterns that modulate the polymer-surface interaction, and this concept is verified experimentally. Length scale pattern control is found to be limited to a scale on the order of a few micrometers.
TL;DR: A noninteracting polystyrene support was developed to obviate the destructive interaction of highly reactive metallocene catalysts with classical silica-based supports while retaining the advantage of supported catalysts.
Abstract: To obviate the destructive interaction of highly reactive metallocene catalysts with classical silica-based supports while retaining the advantage of supported catalysts, a noninteracting polystyrene support was developed. Supported catalysts for the polymerization of alpha-olefins are prepared by treating lightly cross-linked, chloromethylated polystyrene beads consecutively with a secondary amine, an ammonium salt of a weakly coordinating anion, and a neutral dialkylmetallocene. Catalytic sites are distributed homogeneously throughout the support particle, and the polymerization occurs within the bead, in contrast to traditional surface-supported metallocene catalysts. The copolymerization of ethylene and 1-hexene at 40 degreesC affords discrete spherical polyolefin beads with a size (0.3 to 1.4 millimeters) that varies according to the polymerization time.
TL;DR: In this paper, a stepwise pyrolysis procedure where the thermal decomposition of different components of a mixture of poly(vinyl chloride) is performed consecutively at different temperatures is presented.
TL;DR: In this paper, the synthesis of regularly spaced comb polystyrenes and graft polyisoprene/polystyrene copolymers with two branches at each junction point (centipedes) is presented.
Abstract: The synthesis of regularly spaced comb polystyrenes and graft polyisoprene/polystyrene copolymers with two branches at each junction point (centipedes) is presented. The synthetic approach involves...
TL;DR: In this article, mice were prepared from poly(acrylic acid)-graft polystyrene by direct injection of a dioxane solution of the polymer into water containing various concentrations of NaCl.
Abstract: Micelles have been prepared from poly(acrylic acid)-graft-polystyrene by direct injection of a dioxane solution of the polymer into water containing various concentrations of NaCl. The size of the ...
TL;DR: In this article, the adsorption of polystyrene nanospheres that have anionic charges on their surfaces from their aqueous dispersions onto the surfaces of cationic ultrathin polymer films quantitatively and kinetically by using a quartz crystal microbalance (QCM) and scanning electron microscopy (SEM).
Abstract: We studied the adsorption of polystyrene nanospheres that have anionic charges on their surfaces from their aqueous dispersions onto the surfaces of cationic ultrathin polymer films quantitatively and kinetically by using a quartz crystal microbalance (QCM) and scanning electron microscopy (SEM). The polymer films were successively prepared by the alternate adsorption of poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) in the absence or presence of suitable NaCl concentrations onto the QCM substrate so that we could observe their formation process by its frequency shifts. We observed the specific adsorption of the nanospheres by means of electrostatic interaction onto the outermost PAH surface by QCM as well. The dependence of their adsorption amounts against the NaCl concentration in polymer precursor film preparation was a sigmoid curve, indicating that there is a critical charge on/in the film for their adsorption. SEM observations showed monolayer adsorption without three...
TL;DR: In this article, atom transfer radical polymerization has been used to prepare well-defined vinyl macromonomers of polystyrene using vinyl chloroacetate as an initiator.
Abstract: Atom transfer radical polymerization has been used to prepare well-defined vinyl macromonomers of polystyrene using vinyl chloroacetate as an initiator. Because styrene and vinyl chloroacetate do not copolymerize, no branching or incorporation of the initiator into the backbone was observed. Macromonomers of several molecular weights were prepared and copolymerized free radically with N-vinylpyrrolidinone in varying feed ratios in order to produce poly(NVP-g-Sty) graft copolymers. The macromonomers used were of sufficiently high molecular weight to form physical crosslinks in solvents which favor the hydrophilic NVP, such as water, which prevent the copolymer from dissolving and cause it to swell. These materials, therefore, formed hydrogels of swellabilities in water exceeding 95%, depending on the amount of styrene that was incorporated into the copolymer. Limitations of and alternatives to this method are also discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 823–830, 1998
Abstract: The diffusion coefficients of oligomeric radicals in monomer-polymer systems have a major influence on properties such as polymerization rates and molecular weight distributions. The present work reports the results of an extensive set of studies of diffusion coefficients of rubbery ternary systems comprising polymer, diluent, and oligomer, determined by pulsed-field-gradient NMR, at 25 and 40 degrees C. Oligomers of methyl methacrylate (MMA) and of butyl methacrylate (BMA) were synthesized by using a catalytic cobalt chain transfer agent to produce macromonomers with a terminal double bond. Where necessary, these were fractionated by preparative GPC to obtain samples ranging from dimeric to decameric; typical polydispersities were 1.08. Pulsed-field gradient NMR is facilitated by being able to monitor the proton NMR of the CH2 hydrogens on the double bond. Matrixes used were high molecular weight polyMMA and polyBMA, the weight fraction of polymer (w(p)) being varied by adding appropriate amounts of diluent (the saturated equivalents of MMA and BMA, viz., methyl isobutyrate and butyl isobutyrate). Above c* (the concentration at which chains start to overlap), all data for diffusion coefficients Di of an oligomer of degree of polymerization i could be fitted with acceptable accuracy by D-1(w(p))/D-i(w(p)) = i(0.664+2.02wp), for both BMA and MMA oligomers in both MMA and BMA matrixes; the same relation also fits earlier data on styrene oligomers in polystyrene. If more accurate scaling parameters are obtained experimentally for smaller oligomers, these can be used to predict data for higher oligomers with even better reliability. For MMA monomer in pMMA, where free-volume parameters are available, the predicted dependences of monomer diffusion coefficient on w(p) and temperature are in accord with experiment.
TL;DR: In this paper, the surface molecular aggregation structure and surface molecular motions of high-molecular-weight polystyrene/low-molescale poly(methyl methacrylate) (HMW-PS/LMW-PMMA) blend films were investigated on the basis of X-ray photoelectron spectroscopic measurements and scanning force microscopic observations.
Abstract: Surface molecular aggregation structure and surface molecular motions of high-molecular-weight polystyrene/low-molecular-weight poly(methyl methacrylate) (HMW-PS/LMW-PMMA) blend films were investigated on the basis of X-ray photoelectron spectroscopic measurements and scanning force microscopic observations Monodisperse PS with Mn = 1450k, where Mn denotes the number-average molecular-weight, and monodisperse PMMAs with Mn 12k, 42k, 405k, 144k, and 387k were used as HMW-PS and LMW-PMMAs, respectively Static contact angle measurements revealed that the magnitudes of surface free energy, γ, of PMMAs for all Mns studied here were higher than that of PS with Mn = 1450K In the case of the (HMW-PS/LMW-PMMA) blend films, in which the Mn for each PMMA was less than 144K, PMMA was preferentially segregated at the air−polymer interface, even though PMMA had a main chain with a higher γ compared with that of PS It was found from scanning viscoelasticity microscopic measurements that the surface molecular moti
TL;DR: In this paper, a vertical tubular flow furnace was used to incinerate polystyrene spheres (100−300 μm) at different combustion temper atures (800−1200 °C) to determine the effect of temperature and feed size on the particulate and gaseous emissions and their chemical composition.
Abstract: The partitioning of polycyclic aromatic hydrocarbons (PAHs) between the particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres (100−300 μm) at different combustion temper atures (800−1200 °C) to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments (differential mobility particle sizer and/or optical particle counter) to determine the particle size distribution. For chemical composition analyses, the particles were either collected on Teflon filters or split into eight size fractions using a cascade impactor with filter media substrates, while the gaseous products were collected on XAD-2 adsorbent. Gas chromatography/mass spectroscopy (GC/MS) was used to identify and quantify the specific PAH species, their partitioning between the gas and particulate ...
TL;DR: In this article, the thermal stability of styrene grafted and sulfonated poly(vinylidene fluoride), PVDF-g-PSSA, proton conducting membranes has been studied using thermal gravimetric analysis in combination with mass spectrometry and thermochromatography.
Abstract: The thermal stability of styrene grafted and sulfonated poly(vinylidene fluoride), PVDF-g-PSSA, proton conducting membranes has been studied using thermal gravimetric analysis in combination with mass spectrometry and thermochromatography. The matrix polymer, PVDF, and the non-sulfonated counterpart, PVDF-g-PS, were studied as reference materials. It was found that the degradation of the PVDF-g-PS membrane proceeds in two steps starting atca. 340 °C with the evolution of degradation products typical of polystyrene. The PVDF-g-PSSA membranes are stable to around 270 °C even in a strongly oxidising atmosphere. The degradation starts with the simultaneous evolution of water and sulfur dioxide. The polystyrene grafts start decomposing at 340 oC in the PVDF-g-PSSA membranes. Thus the membranes are suitable for tests in electrochemical applications at elevated temperatures.
TL;DR: In this paper, a series of thin films of blends of poly(styrene-d8) and poly(poly(stylrene-co-p-bromox-styrene), where 1 ≥ x ≥ 0, cast on to silicon wafers are examined by atomic force microscopy, X-ray photoelectron spectroscopy, and static secondary ion mass spectrometry.
Abstract: A series of thin films of blends of poly(styrene-d8) and poly(styrene-co-p-bromox-styrene), where 1 ≥ x ≥ 0, cast on to silicon wafers are examined by atomic force microscopy, X-ray photoelectron spectroscopy, and static secondary ion mass spectrometry. Films deposited on wafers stripped of the native oxide are smooth. The poly(styrene-d8) component segregates to the polymer−air interface, and the extent of segregation increases with the degree of bromination. An inverse linear correlation is obtained between the extent of segregation and the polymer compatibility, the latter measured by the interfacial width of bilayer films. For films deposited on wafers retaining the oxide, topographical features are observed with dimensions depending on the blend composition and degree of bromination of the polymer. The bromopolymer forms islands that are raised. The most pronounced topography is found with blends containing the fully brominated styrene. Reducing the degree of bromination increases the polymer compati...
TL;DR: In this paper, small-amplitude oscillatory shear measurements were carried out on polystyrene/polystyrene (PS) sandwich-like assembly as a function of the time of welding in the molten state.
Abstract: Diffusion at the polymer/polymer interface was probed by small-amplitude oscillatory shear measurements carried out on polystyrene (PS)/polystyrene (PS) sandwich-like assembly as a function of the time of welding in the molten state. It was found that the dynamic complex shear modulus G*(t) at a fixed frequency increases with the time of contact in two time regimes. First G*(t) increases proportionally to t1/2 and then a second regime takes place where G*(t) increases proportionally to t1/4. At longer times, G*(t) tends asymptotically toward G* of pure polystyrene. The results were interpreted in terms of reptation theory and the time of transition between the two scaling law regimes was found to be in agreement with the time needed for the transition from the Rouse mode to the reptation mode. Special attention was given to the initial state of the polymer surfaces before contact by performing experiments on (i) freshly prepared surfaces, (ii) presheared samples, (iii) fractured samples, and (iv) corona-t...
TL;DR: In this article, the authors used scanning electron microscopy and wide-angle X-ray diffraction to detect polystyrene in the non-crystalline domains and permeating throughout the spherulitic structure of high density polyethylene (HDPE) substrate.
Abstract: Polystyrene/polyethylene composites have been prepared by the heterogeneous radical polymerization of styrene within supercritical carbon dioxide−swollen high density polyethylene (HDPE) substrates. Composition of the composites can be controlled with reaction time and initial ratio of styrene to HDPE. The polystyrene produced within the substrate is of high molecular weight. Differential scanning calorimetry and wide-angle X-ray diffraction indicate that the crystalline portion of the HDPE substrate is unaffected by the procedure used in this investigation. Scanning electron microscopy indicates that the polystyrene resides in the noncrystalline domains and permeates throughout the spherulitic structure of the HDPE substrates. This morphology is very different from the morphology of polystyrene/polyethylene blends produced by conventional melt/mixing techniques. The strengthening of the spherulitic structure of HDPE produces an efficient enhancement in the modulus of the overall composite. The tensile st...
TL;DR: In this paper, a single hollow polystyrene particle was obtained by suspension polymerization for divinylbenzene/toluene droplets dissolving poly styrene (PS) in an aqueous solution of poly(vinyl alcohol).
Abstract: Polymer particles having single hollow in the inside were successfully prepared by suspension polymerization for divinylbenzene/ toluene droplets dissolving polystyrene (PS) in an aqueous solution of poly(vinyl alcohol). Such a hollow polymer particle was not obtained without PS. The hollow structure was affected by the molecular weight and the concentration of PS.
TL;DR: Titanocene complexes based on an amido-fluorenyl ligand bridged by a dimethylsilylene group, such as (η1:η5-C13H8SiMe2NCMe3)TiCl2 (3) as discussed by the authors, have been synthesized.
Abstract: Titanocene complexes based on an amido-fluorenyl ligand bridged by a dimethylsilylene group, (η1:η5-C13H8SiMe2NCMe3)TiCl2 (3) and (η1:η5-C13H8SiMe2NCMe3)TiMe2 (5), have been synthesized. Reaction of 5 with 1 equiv of [Ph3C][B(C6F5)4] (2) was almost quantitative to give the “cationic” compound [(η1:η5-C13H8SiMe2NCMe3)TiMe]+[B(C6F5)4]- (1), as identified on the basis of elemental analyses and spectroscopic properties. The “cation” 1 was highly active and stereoselective in the copolymerization of ethylene (E) and styrene (S), depending upon the polymerization conditions, to produce predominantly a new microstructural E−S copolymer (together with some polyethylene homopolymer) with an activity of (0.65−1.58) × 105 g of bulk polymer/(mol of Ti·mol of total monomers·h). As thoroughly characterized by solvent extraction, GPC, 13C NMR, DSC, and DMA, the E−S copolymer obtained by catalyst 1 proved to be a perfectly alternating copolymer with well-defined isotactic polystyrene structure, together with a single gla...