Polystyrene In Toluene Research Articles

Transient inhomogeneities in polymeric liquids and solutions: characterization by static and dynamic light scattering

Low molecular weight liquid polyisoprenes and concentrated solutions of polystyrene in toluene were studied by static and dynamic light scattering. Besides the well known density and concentration fluctuations, both systems show an additional slow relaxation mode which is accompanied by a strong scattering at small angles. The relaxation rate of the process is proportional to the square of the scattering vector q. The process seems to be due to the motion of clusters inside the sample. Small angle light scattering experiments indicate a cluster size of the order of 10 −7 m. After several months the clusters disappeared. For the samples under study, cluster formation therefore constituted a non-equilibrium phenomenon.

Ultrasonic degradation of polymer solutions: 2. The effect of temperature, ultrasound intensity and dissolved gases on polystyrene in toluene

Solutions of polystyrene in toluene have been studied as part of a comprehensive study of the parameters affecting the degradation of polymers under irradiation with high-intensity ultrasound. Results are reported which demonstrate the molecular weight dependence of the process and the effect of solution temperature, ultrasound intensity and the nature of dissolved gases on the rate and extent of degradation over a considerably wider range than previously studied. They demonstrate that the limiting molecular weight and polydispersity of the materials can be controlled by suitable manipulation of the experimental conditions. The effects are explained in terms of the influence that each of the parameters has on the shear gradients generated around cavitation bubbles in the solution. The possibility of using the ultrasound process in the control of polymer structure and for the preparation of block copolymers is discussed.

Polystyrene by XPS

X-ray photoelectron spectroscopy was used to analyze a thin film of polystyrene. Spin casting from a 2% by weight solution of polystyrene in toluene was utilized. Film thickness was determined to be 60 nm by ellipsometry. The thin film was examined with a Hewlett Packard 5950A ESCA spectrometer.

Surface tension of dilute polymer solutions. I. A renormalization group approach

The surface tension increment is evaluated for dilute polymer solutions. The first virial coefficient is calculated to first order in excluded volume near two limiting boundary conditions: repulsive (Dirichlet) and reflecting (von Neumann). An interpolation function extends the calculations to intermediate values of the polymer–surface interaction strength and provides the surface pressure as a function of both polymer–polymer and polymer–surface interactions. Comparison with experiments for polystyrene in toluene suggest the importance of nonuniversal contributions to the surface tension increment.

Dynamics in concentrated polymer solutions by polarized Rayleigh–Brillouin scattering and dynamic light scattering

Solutions of polystyrene in toluene in the concentration range 0.1–1.0 g/ml have been examined using polarized Rayleigh–Brillouin scattering and dynamic light scattering. The purpose was to extend measurements to the hitherto little studied interval between semidilute solutions and the bulk polymer. The Brillouin shift increases monotonically with polymer volume fraction (Φp) and a linewidth maximum is observed at about Φp=0.6. Up to Φp=0.56, a single cooperative diffusion mode is found, which passes through a broad maximum at Φp=0.5. For the sample with Φp=0.78, the nature of the main component depends sensitively on temperature. At 17 °C it is purely relaxational (q independent), while at 40 and 50 °C, it is diffusive. At intermediate temperatures, mixed behavior is noted where the dynamic processes overlap because the slower relaxational mode has a stronger temperature dependence. At Φp=0.89, the correlation functions are highly nonexponential and strongly temperature dependent. The bimodal correlation function contains contributions from both concentration fluctuations due to cooperative diffusion and density fluctuations arising from segmental motions in the polymer.

Direct measurements of polymer depletion layers by neutron reflectivity.

We present results of direct measurements of polymer depletion layers at the liquid/air interface using neutron reflectivity. The systems studied are semidilute solutions of polystyrene in toluene using polymers of different molecular weights. The thickness of the depletion layer d is found to be of the order of the correlation length \ensuremath{\xi} of the polymer in the bulk solution. We show, for the first time, the existence of a depletion layer at the free surface of a polymer solution when ${\ensuremath{\gamma}}_{\mathit{p}}$>${\ensuremath{\gamma}}_{\mathit{s}}$, where ${\ensuremath{\gamma}}_{\mathit{p}}$ and ${\ensuremath{\gamma}}_{\mathit{s}}$ are surface tensions of pure polymer and pure solvent, respectively. We show also that the thickness of the depletion layer scales with the bulk concentration ${\mathrm{\ensuremath{\varphi}}}_{\mathit{b}}$ as d\ensuremath{\sim}${\mathrm{\ensuremath{\varphi}}}_{\mathit{b}}^{\mathrm{\ensuremath{-}}0.75}$.

Forces between polymer-bearing surfaces undergoing shear

ADSORBED or grafted polymers are used to control phenomena such as colloidal stability, fluid flow and the tribological properties of surfaces. Forces between polymer-bearing surfaces have been studied comprehensively over the past decade1–10, but little is known about such forces in shear. These are intimately related to the dynamic as well as the equilibrium properties of the surface-attached chains. We have constructed a device that measures directly the forces that act between surfaces bearing polymer layers in a liquid medium as they slide past each other. For the case of mica sheets bearing end-grafted chains of polystyrene in toluene (a good solvent), we find that, as the surfaces move parallel to each other, there is a marked change in the normal forces between them. These become increasingly repulsive at higher velocities. The effect occurs only above certain critical shear rates, probably related to relaxation dynamics of the end-grafted chains themselves. Our findings have direct implications for the properties of polymeric lubricants, and for the rheological behaviour both of stabilized dispersions and of multi-phase polymeric systems.

Behaviour of ring‐shaped polymers in dilute solution. Quantitative calculation and experimental verification for molecular dimensions and second virial coefficient

AbstractRelationships between the ratios of the mean‐square radii of gyration gs and the second virial coefficients gA2 of ring‐shaped and linear polymers with the degree of polymerization P of the polymer and its Peterlin exponent ε in dilute solution were derived theoretically and numerical values calculated. The second virial coefficients of ring‐shaped and of linear polystyrene at 25°C in toluene were determined using light scattering. By verifying the theoretical calculation based on the experimental determination of this polymer‐solvent system with light scattering and other methods reported in the literature, the agreement between theoretical calculation and experimental results is shown. The correlation equations for linear (l) and ring‐shaped (r) polystyrene in toluene at 25°C A2, 1 = 8,06 · 10−3 · M0,224 and A2,r = 6,68 · 10−3 · M0,218 were obtained using light scattering.

Synthesis, glass transition and solution behaviour of carboxylatobetaine telechelic polymers

Telechelic polystyrene and polyisoprene bearing carboxylatobetaine end groups of various intercharge lengths were prepared and characterized. Dimethylamino telechelic polyisoprene and polystyrene were anionically synthesized and the dimethylamine end groups were reacted with bromoalkyl ethylcarboxylic esters, comprising a methyl and an n-butyl group. After treatment with aqueous NaOH, the end groups were converted into carboxylatobetaine form of various intercharge lengths. Glass transition temperatures of both functionalized polystyrene and polyisoprene were found to increase with respect to the precursor polymers and to depend on the intercharge length. A smaller intercharge length appears to promote stronger interactions. Solubility of the carboxylatobetaine form depends on both the polymeric nature of the backbone and the intercharge length of the betaine end group. Highly viscous solutions were obtained when dissolving the polymers in a low polarity solvent. The viscosity of the zwitterionic polystyrenes in toluene was affected by the intercharge length of the end group. An average aggregation number was calculated from the viscosity data and the results were compared with those of randomly grafted carboxylatobetaines of the same zwitterionic molar fraction.

Solvent‐induced crystallization of syndiotactic polystyrene in toluene

AbstractThe diffusion of toluene in glassy syndiotactic polystyrene was analyzed for films with different thickness. It was found that the reduced sorption curves superimpose, denoting that the diffusion follows a Fickian behaviour. The intensity of transmitted light in a polarizing microscope was followed during swelling, and it was found that there is development of order and it is strongly diffusion‐controlled.Films dried after immersion in toluene show a crystalline wide angle X‐ray pattern, while in the swollen state the possibility of a liquid‐crystalline‐like state can be suggested.

A simple method analyzing 2H nuclear magnetic resonance line shapes to determine the activation energy distribution of mobile guest molecules in disordered systems

We investigated the 2H nuclear magnetic resonance (NMR) line shape of deuterated benzene and hexamethylbenzene as guest molecules in organic glasses in the temperature range of 10–150 K. A broad distribution G(ln τ) of correlation times determines the slowing down of the molecular reorientation around the sixfold symmetry axis of the guests. The line shape is described by a superposition of temperature-dependent fractions F(T) of only two subspectra corresponding to fast and slowly rotating molecules; no spectra characteristic for intermediate mobility as found in crystal matrices are observed. Assuming a thermally activated motional process, the temperature dependence of G(ln τ) comes from a temperature-independent distribution of activation energies g(E). In this case, the derivative of the fraction dF(T)/dT yields directly the distribution g(E). Using this method an asymmetric distribution g(E) with its maximum at the low energy side is found for the glasses. While the general shape of g(E) is similar for different matrices, the mean activation energy differs significantly. We used the same approach to discuss similar ‘‘two-phase’’ spectra for the isotropic reorientation of toluene in polystyrene below the glass transition of the mixed system. Here, an alternative explanation is offered considering a distribution of glass transition points Tg for the dynamics of toluene in the mixed system.

Bubble nucleation in polymeric liquids. I. Bubble nucleation in concentrated polymer solutions

AbstractLaser light scattering, with the aid of Mie's scattering theory, was used to investigate bubble nucleation in concentrated polymer solutions. Solutions with 40, 50 and 60 wt % polystyrene in toluene were used. A test solution in a high‐pressure optical cell made of strain‐free quartz was heated to a predetermined temperature under pressure. Upon release of the pressure in the cell, both scattered and transmitted light fluxes were measured with photomultipliers, and the variation of system pressure with time was measured using a piezoelectric pressure transducer. The measurement of the light scattering flux and control of the experiment were performed by means of a microcomputer with a general‐purpose data acquisition interface. Data reduction was done using the same microcomputer. The critical bubble size was determined by obtaining a one‐to‐one correspondence between the extrema of the experimental and theoretical scattering curves. While the Mie scattering theory is for monodisperse particles, the experimental scattering curves indicated that the bubbles had a distribution of sizes. Therefore, the log‐normal distribution function was used to represent the size distribution; and theoretical scattering curves were computed by varying the breadth parameter in the log‐normal distribution function, until we had a one‐to‐one correspondence between the extrema of the experimental and theoretical scattering curves. In this way, we were able to determine (a) the size distribution of bubbles in the optical cell, (b) the critical bubble size, (c) the total number of bubbles nucleated, and (d) the critical pressure for bubble nucleation, as functions of temperature, the initial equilibrium pressure in the optical cell, and the concentration of the polymer solution.

Concurrent static and dynamic light scattering from macromolecular solutions. 1. Model systems in the low q regime

Concurrent acquisition of static and dynamic light scattering data has been performed on model systems of dilute narrow molecular weight distribution polystyrenes in toluene and also on dilute suspensions of monodisperse polystyrene lattices in water. The data were analysed to extract a self consistent set of thermodynamic (molecular weight, radius of gyration, virial coefficient) and hydrodynamic (diffusion coefficient) results. It is demonstrated that the intensity autocorrelation function can be analysed to determine the absolute magnitude of the temporal-spatial scattering surface and can therefore provide the results which would normally be obtained from a separate static light scattering experiment. Preliminary results in the intermediate q regime suggest that with a concurrent analysis scheme of the type demonstrated here it will be possible to analyse in further detail the transition of the scattering function from q 2 to q 3 dependence.

Viscosity–temperature relationships for linear and 12‐arm star polystyrenes in dilute solution

AbstractThe actual viscosities (cP) of dilute solutions of linear and 12‐arm star polystyrenes were measured in benzene, a good solvent, and cyclohexane, a poor to moderate solvent, as a function of temperature. The equations of Moore, previously established for solutions of linear polymers, were also found to be valid for star polystyrenes. A branching parameter b was defined which is essentially the same as g′ = [η]br/[η]1. The values of b found in benzene are close to the value of g′ for 12‐arm star polystyrene in toluene, another thermodynamically good solvent. It thus appears that Moore's relationships have at least limited utility in studying branching in polymers.

Reagents on styrene-divinylbenzene supports with improved accessibility

Macroporous styrene-divinylbenzene copolymers have been prepared using a solution of polystyrene in toluene as a porogenic diluent. Pore volume and pore size distribution are critically dependent on both the amount and the concentration of the diluent solution. Attempts to graft first a radical azo generator and then to use it for grafting a functional polymer are described but were not fully successful. A second approach was the post-polymerization of vinylbenzyl chloride through the residual double bonds of the initial resin, after swelling in a concentrated solution of the monomer. The chloromethylated porous resin was further derivatized to a sulfoxide containing one. A two-step process was employed involving first a phase transfer sulfuration and then an oxidation. The first reaction was limited to an extent depending mostly on the initial chlorine content of the resin. The final product was used as a catalyst for the alkylation of benzyl cyanide with butyl bromide. The catalytic activity, although lower than that of a soluble copolymer of the same composition as the graft, was definitely higher in terms of rate and upper limit than that of conventional macroporous or gel-type catalysts.

Measurement of thermal diffusion parameters of polystyrene using a thermal field flow fractionation method

Thermal diffustor parameters such as the thermal diffusion factor and the thermal diffusion coefficient for polystyrene in toluene are measured by using a thermal field flow fractionation (TFFF) method The dependence of these parameters upon temperature concentration and polymer molecular weight is ex-amined.

The particle scattering function and the distribution functions in the interior of fully swollen polymer molecules

The particle scattering function and the distribution function for the spatial distance between two interior elements were determined by light scattering measurements on fully swollen polymers, polystyrenes in toluene, and poly (α-methylstyrenes) in benzene. Measurements were made in the large q region such that x=q2〈s2N〉 was 20 to 100. Here 〈s2N〉 is the mean-square radius of gyration and q the magnitude of the scattering vector. The distribution function is well represented by the generalized Domb–Gillis–Wilmers form W(r,n)=Cnrl exp[−(r/σn)t] with t=2.40 and l=2.80. Here n is the length of a polymer segment, r is the end-to-end distance of the segment, Cn is the normalization constant, and σn is the scaling factor, respectively. The value of l is considerably high as compared with 2.0 for a Gaussian chain and 2.27 for the end-to-end distance of the self-avoiding chain, but is favorably compared with des Cloizeaux’s estimate, 2.71, for the distance between interior elements. Thus the effect of dangling ends is detectable by the study of the particle scattering function.

Remarks on A2, hydrodynamic coil expansion, and concentration dependence of the diffusion coefficient for polystyrene in toluene

Remarks on A2, hydrodynamic coil expansion, and concentration dependence of the diffusion coefficient for polystyrene in toluene

Small-angle x-ray scattering from semidilute polymer solutions. I. Polystyrene in toluene

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSmall-angle x-ray scattering from semidilute polymer solutions. I. Polystyrene in tolueneFumiyuki Hamada, Shinichi Kinugasa, Hisao Hayashi, and Akio NakajimaCite this: Macromolecules 1985, 18, 11, 2290–2294Publication Date (Print):November 1, 1985Publication History Published online1 May 2002Published inissue 1 November 1985https://doi.org/10.1021/ma00153a042RIGHTS & PERMISSIONSArticle Views277Altmetric-Citations29LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (582 KB) Get e-Alerts Get e-Alerts

Small angle neutron scattering (SANS) of cyclic and linear polystyrene in toluene

AbstractSamples of ring and open chain polystyrene in dilute perdeuterated toluene solution were measured by small angle neutron scattering up to a value of the scattering vector Q = 2 nm−1. The molar masses 12000 ≤ M/(g/mol) ≤ 22000, the mean square radii of gyration 〈R2〉 and the second virial coefficients A2 of the samples were determined. The results are compared to theories which describe the dependencies 〈R2〉 = f(M) and A2 = f(M) for both cyclic and linear chain molecules. A qualitative agreement between theory and experiment is obtained.