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Showing papers on "Polystyrene published in 1980"



Journal ArticleDOI
TL;DR: In this article, the authors show that at high loadings of peptide in a solvent such as DMF, the peptide component has a dominating influence on the swelling of the polystyrene beads.
Abstract: Peptide-resins containing linear peptides up to 6000 molecular weight-were prepared by stepwise solid-phase synthesis of the repeating model sequence Leu-Ala-Gly-Val-oxymethylphenylacetic acid on copoly(styrene-l% divinylbenzene) resin beads. Initial substitutions of 0.22 and 0.95 mmol/g of polystyrene were used and the resulting peptide-resins contained 11-81% peptide. Representative samples were taken after the addition of each model sequence unit and the diameters of the dry beads were measured by direct microscopic examination. The volume of 1 g of the unsubstituted dry beads was 1.0 mL and was found to increase by more than fivefold as the peptide content approached 80%. Similar measurements of the samples in CH2Cl2 or DMF showed that the swollen volumes of 1 g of the unsubstituted beads were 6.2 and 3.3 mL, respectively. The volumes of the swollen peptide-resins showed a dramatic increase in the course of the synthesis, and at 80% peptide the volumes/g of polystyrene were 12 mL in CH2Cl2 and 28 mL in DMF. There was no indication that the upper limits of swelling of the peptide-containing resin had been reached. The solvation properties of the cross-linked polymer network and the pendant peptide chains mutually affect one another and at high loadings of peptide in a solvent such as DMF the peptide component has a dominating influence on the swelling of the peptide-resin beads. The swelling of the unsubstituted resin is due to a decrease in free energy from solvation of the polystyrene and, at equilibrium, is balanced by the elastic restraining force resulting from deformation of the loosely cross-linked polymer network. The increased swelling of the peptide-resin can then be attributed to the additional net decrease in free energy from solvation of the linear peptide chains, which is counteracted by an increase in the elastic restraining force arising from further deformation of the loosely cross-linked network structure of the polymer support. No such additional counterforce is expected to arise from deformation of the linear peptide chain imposed by the expansion of the polymeric support. In either CH2Cl2 or DMF, the space available for peptide chain growth within the swollen resin beads is not a limiting factor in solid-phase peptide synthesis. After the synthesis of the 60-residue model there was actually more space within the bead for chain growth than at the beginning of the synthesis. The results of this study allow a rational choice of the level of loading of peptide on the resin and of an appropriate protocol for the synthesis of a particular peptide.

164 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used the light scattering technique to measure the phase separation temperatures (cloud points) of mixtures containing a polystyrene and a polybutadiene of various molecular weights.
Abstract: : The light scattering technique was utilized to measure the phase separation temperatures (cloud points) of mixtures containing a polystyrene and a polybutadiene of various molecular weights and also of mixtures containing a polystyrene and a random or block copolymer of styrene and butadiene. The data was analyzed to obtain the polymer-polymer interaction parameter for the styrene-butadiene pair as a function of temperature and concentration. The value of the parameter deduced from the homopolymer mixtures agrees well with that obtained from the mixtures containing a copolymer. The polymer-polymer interaction parameter thus evaluated was compared with a theoretical expression derived on the basis of the Flory equation-of-state theory. The effect of the free volume disparity between the two components was found to play a relatively minor role in determining the interaction parameter when the two polymers lack any specific interactions which would make them mutually miscible. (Author)

140 citations


Journal ArticleDOI
TL;DR: In this article, a ring-shaped macromolecules have been synthesized by the reaction of a bifunctional "living" polystyrene with a stoichiometric amount of dibromo-p -xylene, at very low concentration.

132 citations




Journal ArticleDOI
TL;DR: In this paper, the conditions for the formation of core-shell structures for triblock copolymers Cop A-B-C, having three sequences of different types, in this case, poly(styrene-b-isoprene)-b-methyl methacrylate, were given.
Abstract: New morphologies, especially “core-shell” and multilayered structures (“onion structure”) have been obtained for polymer blends containing block copolymers. For triblock copolymers Cop A-B-C, having three sequences of different types, in this case, poly(styrene-b-isoprene-b-methyl methacrylate), the conditions are given for the formation of core-shell structures. A scheme is presented showing the structures of the mesomorphic phases, as a function of the composition of the copolymer. Multilayered and core-shell structures have also been obtained by a suitable combination of two diblock copolymers, Cop A-B, i.e., poly(styrene-b-isoprene), with a corresponding homopolymer, i. e., polystyrene. One of the copolymers can act as an emulsifier for the second one forming the dispersed phase of the blend. An extension of the classical mesomorphic structures is presented, and it is shown that the emulsifying effect of block copolymers is quite general.

87 citations



Patent
20 Oct 1980
TL;DR: Vibration isolators are manufactured by a co-injection molding process as mentioned in this paper, where the outer and inner parts of the isolator are molded first from a rigid or stiff thermoplastic material such as polystyrene and intermediate spring-like parts are made of a thermopolymer such as copolymer of butadiene and styrene formed and bonded to the inner parts in a subsequent molding step.
Abstract: Vibration isolators are manufactured by a co-injection molding process. Outer and inner parts of the isolators are molded first from a rigid or stiff thermoplastic material such as polystyrene and intermediate spring-like parts of the isolators are made of a thermoplastic elastomer such as copolymer of butadiene and styrene formed and bonded to the outer and inner parts in a subsequent molding step.

79 citations


Journal ArticleDOI
TL;DR: In this paper, the reaction of hydrogen peroxide by catalysis with polystyrene containing Mt-Pc rings was carried out in heterogeneous aqueous media at pH 7,0.
Abstract: Metal-4,4′,4″,4″′-tetracarboxyphthalocyanine [Metal = Fe(III), Co(II), Mt-taPc] were synthesized by the hydrolysis of metal-4,4′,4″,4″′-tetracarboxamidephthalocyanine (Mt-tamPc). These metal-taPc are soluble in water and in aprotic polar solvents such as N,N′-dimethylformamide. Poly(styrene) bonded Mt-taPc was synthesized by Friedel-Crafts reaction of poly(styrene) with Mt-taPc tetraacid chloride. The polymers contain about 4 mole-% Mt-Pc rings which are covalently bonded to poly(styrene). The decomposition reaction of hydrogen peroxide by catalysis with polystyrene containing Mt-Pc rings was carried out in heterogeneous aqueous media at pH 7,0. The polymer catalysts show a catalase-like activity. The activation energies with the polymer bonded Mt-Pc were found to be about half of those with Mt-taPc. From continuous flow experiments in a column, the polymer attached catalyst was found to be very stable, compared with free Mt-taPc.

77 citations


Journal ArticleDOI
TL;DR: In this article, the reaction order, the activation energy and the preexponential factor were evaluated from common TG curves experimentally obtained, in most cases a 5-mg sample of polystyrene with 110,000 molecular weight was decomposed at heating rate of 10°C/min.
Abstract: Various methods of thermogravimetric analysis were compared in case of polystyrene degradation. The reaction order, the activation energy and the preexponential factor were evaluated from common TG curves experimentally obtained. In most cases a 5-mg sample of polystyrene with 110,000 molecular weight was decomposed at heating rate of 10°C/min. The reaction was found under this experimental condition to be of first order with activation energy of 61.0 kcal/mole, though there were slight differences depending on the analytical methods used.

Journal ArticleDOI
TL;DR: In this article, an investigation was made of micelle formation by polystyrene polybutadiene polypolystyrene block copolymer in ethyl acetate, which is a selectively bad solvent for poly butadiene; the number-average molecular weights of the three blocks were 12900, 66000 and 13700, respectively.
Abstract: An investigation has been made of micelle formation by a polystyrene–polybutadiene–polystyrene block copolymer in ethyl acetate, which is a selectively bad solvent for polybutadiene; the number-average molecular weights of the three blocks were 12900, 66000 and 13700, respectively. As the temperature was raised dilute solutions of the copolymer in ethyl acetate showed a distinct cloud-point, which moved to higher temperatures with increases in concentration. On raising the temperature further the solutions gradually became clear again.Light scattering and electron microscopy studies showed that the onset of cloudiness was due to the formation of long worm-like micelles from spherical micelles. The clearing of solutions at higher temperatures occurred because the micelles dissociated to form copolymer molecules in the free-chain form. The cores of both types of micelle were composed of swollen polybutadiene blocks and the outer fringes of the micelles of polystyrene blocks. The spherical micelles had a fairly narrow size distribution. The worm-like micelles had a wide distribution of contour lengths but possessed a narrow size distribution in the radial direction.A second polystyrene–polybutadiene–polystyrene copolymer having shorter blocks than the first copolymer showed a similar type of solution behaviour at lower temperaturs.



Journal ArticleDOI
TL;DR: In this article, turbulent drag reduction measurements were used to augment the usual analytical techniques of viscosity and gel permeation chromatography to evaluate the effects of polystyrene degradation, and the degradation causes a shift in the distribution to lower molecular weights with little change in the shape.
Abstract: The flow-assisted degradation behavior of polystyrene was studied as a function of solvent, polymer concentration, molecular weight, and molecular weight distribution. To obtain data at concentrations as low as 100 parts per million by weight, turbulent drag reduction measurements were used to augment the usual analytical techniques of viscosity and gel permeation chromatography. Turbulent flow measurements were found to be a valuable technique for evaluating the effects of degradation: the drag reduction onset point provides information about the largest molecules in the sample while the flow rate dependence is related to the shape of the top part of the molecular weight distribution. For the polymers and flow conditions studied, the degradation causes a shift in the distribution to lower molecular weights with little change in the shape. This suggests a complex mechanism where the probability of bond scission is not random but varies along the polymer backbone.

Journal ArticleDOI
TL;DR: In this paper, the viscoelastic properties of monodisperse polystyrene latexes were measured through an order-disorder transition as varying the salt concentration in the solvent and the volume fraction of spheres.
Abstract: The viscoelastic behaviour at 40 kHz and the steady flow properties of monodisperse polystyrene latexes, i.e. aqueous suspensions of charged polystyrene spheres, were measured through an order-disorder transition as varying the salt concentration in the solvent and the volume fraction of spheres. A latex in the ordered lattice structure showed the rigidity of about 103 dyn/cm2 and the yield stress of about 1 dyn/cm2, which indicates that the ordered latex is a crystal in view of the mechanical properties. The ratio, 10-3, of the yield stress to the rigidity suggests a dislocation mechanism of the plastic flow of the ordered latex.


Journal ArticleDOI
A. C. Ouano1, J. A. Carothers1
TL;DR: A critical angle illumination microscopy technique was used to study the in situ dissolution dynamics of polystyrene, poly (α-methylstyrene) and the two tactic forms of poly (methyl methacrylate), (PMMA), in several solvents as discussed by the authors.
Abstract: A critical angle illumination microscopy technique was used to study the in situ dissolution dynamics of polystyrene, poly (α-methylstyrene) and the two tactic forms of poly (methyl methacrylate), (PMMA), in several solvents. The dissolution characteristics; of polymers were found to be greatly influenced by several factors: type of polymer, processing condition of the sample, type of solvent, and tacticity, Polystyrene was found to exhibit extensive swelling in several solvents while atactic PMMA exhibited extensive cracking on dissolution. Isotactic PMMA, which has a glass temperature of about 70°C lower than the atactic PMMA, showed swelling behavior similar to atactic polystyrene, while the α-methylstyrene showed the cracking phenomena exhibited by atactic PMMA.

Journal ArticleDOI
TL;DR: In this article, three analytical techniques for the extent of sulfonation were employed: ion exchange of the films with methylene blue, a cationic dye, and subsequent visible light absorption measurement; direct titration of the sulfonic acid groups; and direct reaction depth measurement by interferometry.
Abstract: Polystyrene surfaces are readily sulfonated by 100% sulfuric acid at room temperature. For reproducible results, the reaction must be carried out under anhydrous conditions. Controlled reaction from zero to more than 4000 monolayers is possible in times less than 1 h. Three analytical techniques for the extent of sulfonation were employed: (1) ion exchange of the films with methylene blue, a cationic dye, and subsequent visible light absorption measurement; (2) direct titration of the sulfonic acid groups; and (3) direct reaction depth measurement by interferometry. The reaction consists of two distinct processes: a rapid initial rate and a slower final rate. These are interpreted as being due to surface and "bulk' sulfonation, respectively, or alternatively the interplay of diffusion and reaction processes.

Journal ArticleDOI
TL;DR: Tapered block polymers of styrene and isoprene were prepared by copolymerization of these two monomers, containing a trace amount of THF in the primary structure.
Abstract: Tapered block polymers of styrene and isoprene were prepared by copolymerization of these two monomers, containing a trace amount of THF. s-BuLi was used as an initiator, and benzene as the polymerization solvent. Analyses based on pyrolysis gas chromatography and 1H NMR indicated that a considerable amount of mixing of these two monomers took place in the block polymer chain, e.g., for TB-1 to TB-3. Such mixing in the primary structure is considered phenomenologically to give rise to the polystyrene-rich block chain and polyisoprene-rich block chain. The repulsive interaction between the two block chains is much weaker than that between the pure polystyrene and polyisoprene block chains, and this enhances the mixing of the polystyrene-rich chain and polyisoprene-rich chain, resulting in a microdomain structure consisting of the polystyrene-rich phase and polyisoprene-rich phase. Owing to this segmental mixing within each phase, the tapered polymer exhibits a lower critical temperature and the unique mechanical properties, in compared to ideal block polymers. The tapered block polymers have the unique solubilizing power of the corresponding homopolymers, arising from their microdomain structures.

Journal ArticleDOI
TL;DR: The Merrifield polystyrene resin, 2% cross-linked by divinylbenzene, is as efficient as the polyacrylmorpholide resin for the synthesis of polydeoxyribonucleotides using a phosphotriester method.
Abstract: Contrary to the expectation, the Merrifield polystyrene resin, 2% cross-linked by divinylbenzene, is as efficient as the polyacrylmorpholide resin for the synthesis of polydeoxyribonucleotides using a phosphotriester method. On the Merrifield resin, the tetradecamer, dTpCpGpTpCpApApCpTpGpGpCpTpT, and the hexadecamer, dCpCpApGpTpCpApCpGpApCpGpTpTpGpT, were synthesized by the phosphotriester method using di and trinucleotide blocks as coupling units.

Journal ArticleDOI
TL;DR: In this article, the adsorption of polystyrene having a molecular weight ranging from 600 to 2,000,000 onto Aerosil 130 from cyclohexane solutions at the theta temperature was studied by UV and IR spectroscopy.
Abstract: Adsorption of polystyrene having a molecular weight ranging from 600 to 2,000,000 onto Aerosil 130 from cyclohexane solutions at the theta temperature was studied by UV and IR spectroscopy. Adsorbance, (A) was determined using UV spectroscopy while both the fraction of the surface sites occupied, (Σ) and the fraction of the segments adsorbed per polymer chain, (p) were measured by IR spectroscopy. Adsorbance increases with increasing molecular weight up to Mw=50×104 and then levels off. The value of Σ increases while the p value decreases with increasing molecular weight. The close correlation between the adsorbed amount Γ per site determined UV spectroscopy and the ratio Σ/p measured by IR spectroscopy can be observed except for cases involving high molecular weight samples. The data were compared with the theories of Scheutjens and Fleer and Silberberg based on a lattice model. There was excellent agreement between the data and these theories.

Journal ArticleDOI
TL;DR: In this article, the stability of binary dispersions consisting of an aluminum hydrous oxide sol and an anionic polystyrene (PS) latex or of the same anionic PS latex in a mixture with a cationic polystrene latex was studied at constant ionic strength as a function of pH and of the ratio of the particle number concentration.

Patent
17 Dec 1980
TL;DR: In this paper, a combination of a styrene-butadiene block copolymer rubber, a nitrile barrier resin, and a high impact polystyrene is used as a tie layer to adhere together co-extruded nitrie barrier resin and high-impact poly styrene.
Abstract: A blend of a styrene-butadiene block copolymer rubber, a nitrile barrier resin, and a high impact polystyrene is used as a tie layer to adhere together co-extruded nitrile barrier resin and high impact polystyrene.


Journal ArticleDOI
TL;DR: In this paper, the photo-oxidation of the model compound 2-phenyl-butane was studied and the resulting oxidized compounds have been separated and analyzed using a combined gas chromatograph-mass spectrometer.
Abstract: Polystyrene is degraded, oxidized and discolored when exposed to sunlight under atmospheric conditions. The chemical effects are ascribed to hydroperoxy, hydroxyl and carbonyl group formation. Chemical and spectroscopic data are not specific enough for identification of these different groups. Therefore, we have studied the photo-oxidation of the model compound 2-phenyl—butane. The resulting oxidized compounds have been separated and analyzed using a combined gas chromatograph-mass spectrometer. Mechanisms for the photo-oxidation of the model compounds have been proposed. By comparing these results with photooxidation data for polystyrene film, conclusions on the oxidation and degradation of the polymer have been outlined, including the carbonyl and hydroxyl group formation. The yellowing of the polymer is largely caused by phenyl ring opening reactions, for which probable mechanisms are suggested.

Journal ArticleDOI
TL;DR: In this paper, it was shown that in dilute solution in a selective solvent for polyelectrolytic polyvinylpyridinium moities, there is multimerization, i.e. presence of particles constituted by several macromolecules.
Abstract: Hydrophobic-hydrophilic polystyrene/poly(4-vinyl-N-ethylpyridinium bromide) (poly-(l-phenylethylene)/poly[l-(N-ethyl-4-pyridinio)ethylene bromide]) block or graft copolymers were synthesized. These copolymers are well defined products, and are homogeneous in mole- cular weight and composition. They were obtained by quaternization, with ethyl bromide, of the nitrogen atoms of pyridine units of polystyrene/poly(4-vinylpyridine) block or graft copolymers. In dilute solution in a selective solvent for polyelectrolytic polyvinylpyridinium moities (water + salt), there is multimerization, i. e. presence of particles constituted by several macromolecules. Light scattering and ultracentrifugation measurements show that this multimerization is not the expected “micellization”, i.e. an “association” phenomenon due to the amphiphilic character of the copolymer, but corresponds Lo an “aggregation” phenomenon, resulting from incomplete dissolution of the product at the molecular scale.

Journal ArticleDOI
Don D. Davis1, T. K. Kwei1
TL;DR: In this article, the possibility of transforming a polystyrene mixture into a homogeneous one by increasing the temperature of the polyvinyl methyl ether (PME) solvent was investigated.
Abstract: Homogeneous films comprised of mixtures of polystyrene and poly(vinyl methyl ether) can be obtained by evaporation from a ternary solution containing toluene as the solvent. Heterogeneous films result when the solvent is trichloroethylene. The possibility that a heterogeneous film cast from trichloroethylene can be transformed to a homogeneous one by physical means is a logical expectation when the polymer-polymer interaction is favorable, though as yet no comprehensive report has appeared in the literature. We have accomplished the transformation by increasing the temperature. Optical microscopy and glass transition experiments were employed to observe the effects.

Journal ArticleDOI
01 Jul 1980-Polymer
TL;DR: In this paper, the authors used polystyrene resin-supported oligo-oxyethylenes as catalysts in the reaction of solid potassium phenoxide with 1-bromobutane in toluene.

Journal ArticleDOI
TL;DR: In this paper, a mixture of general-purpose polystyrene and poly(methyl methacrylate) was melt blended in a special mixer-extruder over a complete range of compositions from 100% polystyrenes to 100% methyl methacrates, and the results were characterized for their melt rheological characteristics in a melt elasticity tester.
Abstract: Samples of general-purpose polystyrene and poly(methyl methacrylate) were melt blended in a special mixer–extruder over the complete range of compositions from 100% polystyrene to 100% poly(methyl methacrylate). The blends were characterized for their melt rheological characteristics in a melt elasticity tester which measured their stress–strain behavior and strain recovery characteristics as a function of time. In addition, the blends were processed through a laboratory fiber spinning apparatus wherein the spinline tension was measured. Large maxima in the amount of recoverable strain, in the time for the strain recovery to finish, and in the melt tension were observed at a weight percent composition of 40% polystyrene and 60% poly(methyl methacrylate). The melt stress-strain curves showed double yield points at certain compositions. The results are discussed in terms of a model consisting of two interpenetrating continuous phases.