Diffusion Coefficient Of Polystyrene Research Articles

Phase Equilibrium and Interdiffusion in Blends of Polystyrene with Polyacrylates.

The solubility and interdiffusion of polystyrene (PS) with polymethyl acrylate (PMA), polyethyl acrylate (PEA), polybutyl acrylate (PBA), and polyethylhexyl acrylate (PEHA) have been studied by the optical interferometry method. Phase state diagrams are plotted. It is shown that they are characterized by the upper critical solution temperatures (UCST), which are localized in the temperature range above 450 K. Pair interaction parameters and their temperature dependences are determined and analyzed. Extrapolation of the temperature dependence of the interaction parameter was used to construct the dome of binodal curves and determine the spinodal curves in the framework of the Flory–Huggins theory. The diffusion coefficients of polystyrene into polyacrylates and polyacrylates into polystyrene are calculated. The dependences of the interdiffusion coefficients on the concentration, temperature, polystyrene molecular weight, and the number of carbons in the side chain of polyacrylate are analyzed. The numerical values of the interdiffusion coefficients of PS-1 into polyacrylates at 433 K change as −8.5 → −6.7 → −6.4 in the homologous series PMA → PEA → PBA. The coefficients of friction are calculated and the effect of change in the matrix structure on the diffusion of polystyrene in them is estimated.

Defining the subcellular interface of nanoparticles by live-cell imaging.

Understanding of nanoparticle-bio-interactions within living cells requires knowledge about the dynamic behavior of nanomaterials during their cellular uptake, intracellular traffic and mutual reactions with cell organelles. Here, we introduce a protocol of combined kinetic imaging techniques that enables investigation of exemplary fluorochrome-labelled nanoparticles concerning their intracellular fate. By time-lapse confocal microscopy we observe fast, dynamin-dependent uptake of polystyrene and silica nanoparticles via the cell membrane within seconds. Fluorescence recovery after photobleaching (FRAP) experiments reveal fast and complete exchange of the investigated nanoparticles at mitochondria, cytoplasmic vesicles or the nuclear envelope. Nuclear translocation is observed within minutes by free diffusion and active transport. Fluorescence correlation spectroscopy (FCS) and raster image correlation spectroscopy (RICS) indicate diffusion coefficients of polystyrene and silica nanoparticles in the nucleus and the cytoplasm that are consistent with particle motion in living cells based on diffusion. Determination of the apparent hydrodynamic radii by FCS and RICS shows that nanoparticles exert their cytoplasmic and nuclear effects mainly as mobile, monodisperse entities. Thus, a complete toolkit of fluorescence fluctuation microscopy is presented for the investigation of nanomaterial biophysics in subcellular microenvironments that contributes to develop a framework of intracellular nanoparticle delivery routes.

Determination of polystyrene–carbon dioxide–decahydronaphthalene solution properties by high pressure dynamic light scattering

The diffusion coefficients of polystyrene (PS) in decahydronaphthalene (DHN) and in solutions of carbon dioxide (CO2) and DHN were measured for dilute PS solutions over a range of temperatures and CO2–DHN ratios using high pressure dynamic light scattering. Infinite dilution diffusion coefficients (D0) of PS and dynamic second virial coefficients (kD) were determined for essentially monodisperse 308kDa PS. At a system pressure of 20.7MPa, PS diffusion coefficients increased by a factor of 2.5, and the activation energy of diffusion decreased by approximately 16% when DHN was “expanded” with 44mol% CO2. However, the hydrodynamic radius of PS at a given temperature was not particularly sensitive to the CO2 concentration. Solvent quality, as measured by kD, decreased at higher CO2 concentrations. The addition of CO2 to polymer solutions may offer a way to “tune” the properties of the solution to facilitate the heterogeneous catalytic hydrogenation of polymers.

SANS Study of Sulfonate End Group Effect on Polystyrene Self-Diffusion

Film formation from a latex involves interdiffusion of polymer chains. The interdiffusion behavior of polystyrene with H ends, one sulfonate end, and two sulfonate ends are compared via small-angle neutron scattering (SANS) and a direct nonradiative energy transfer technique (DET) at short times. High molecular weight (Mn ≅ 300 000) anionically synthesized polystyrenes were confined in latex particles utilizing an artificial miniemulsification technique. Interdiffusion of the polystyrenes in a latex film was carried out at temperatures of 125−145 °C. The diffusion coefficients of polystyrene with H ends were five times and 10 times higher than that of polystyrene with one sulfonate end and two sulfonate ends, respectively. The probable cause is end-to-end aggregation of the chains, supported by the ratio Rg/M1/2 remaining substantially constant.

Comparison of the Self Diffusion Coefficient of Polystyrene in Solution Estimated by Forced Rayleigh Scattering and Fluorescence Recovery after Photobleaching

The self diffusion coefficient Ds of two labeled polystyrene (PS) samples in dibutyl phthalate (DBP) has been measured in the range of polymer concentration from 0.1 to 50 wt% using forced Rayleigh scattering (FRS) and fluorescence recovery after photobleaching (FRAP). 2-Nitro-4-carboxy-4′-dimethylaminostilbene and 4-glycyl-7-nitrobenzofurazan have been used as photochromic dyes for FRS and FRAP measurements, respectively. Good agreement has been found between two sets of Ds data in the range of Ds from 10−8 to 10−12 cm2 s−1 within experimental error. In the dilute region of c≤1 wt%, mutual diffusion coefficient D of unlabeled but otherwise the same PSs in DBP has been measured by dynamic light scattering. The Ds assymptotically approached D with decreasing polymer concentration.

The behavior of the tracer diffusion coefficient of polystyrene in isorefractive “solvents” composed of poly(vinyl methyl ether) ando-Fluorotoluene

In this paper, we describe and use a relatively new technique — dynamic light scattering from refractive index-matched ternary solutions-to study a quantity very closely related to the self-diffusion coefficient in binary systems. We refer to this quantity as the tracer diffusion coefficient. This tracer diffusion coefficient is expected to behave in much the same way as the self-diffusion coefficient, in terms of its concentration and molecular weight dependencies. In this study, we use two compatible polymers, polystyrene and poly(vinyl methyl ether), and a solvent, o-fluorotoluene, chosen specifically because its refractive index matches that of the poly(vinyl methyl ether). The technique is advantageous in that it allows the experimenter to vary independently the molecular weight of both the probe and “invisible” matrix polymers, their individual molecular topologies, and the overall polymer concentration with relative ease. No special chemical tagging is required, although it must be borne in mind that we are not measuring self-diffusion but the diffusion of a dissimilar tracer. Our experiments probe the diffusion of linear polystyrenes in matrices composed of linear poly(vinyl methyl ether)/o-fluorotoluene. Our results show a crossover from non-free draining (Zimm) to free draining (Rouse) hydrodynamic behavior of polystyrene as the concentration of the invisible poly(vinyl methyl ether) making up the matrix is increased.

Temperature dependence of self diffusion of polystyrene and polyethylene in the melt an interpretation in terms of the free volume theory

The temperatur dependence of the self diffusion coefficients of polystyrene and polyethylene in the melt was measured with the pulsed field gradient nmr technique. The temperature and molar mass dependences of the self diffusion coefficients can be described by the free volume model. Taking into account the matrix effect we detected the beginning of the break of the reptation process for polystyrene at low molar masses. The activation energies of the self diffusion process are comparable with those observed for viscosity.

Diffusion measurement of tritium labeled polystyrene in polymer bulk. Effect of molecular weight on diffusion coefficient.

The diffusion coefficients of polystyrene in polymer bulk were measured at 150°C by a radioactive tracer method over the range of molecular weight 1.10×105-1.80×106 for active polymer and 4.00×103-1.80×106 for inactive base polymer. The effects of molecular weight on diffusion coefficients are discussed from the experimental data obtained in this work. For one-component systems, it was disclosed that Bueche''s well-known relationship of diffusion coefficient, D, with viscosity, η, and temperature, T, i.e., Dη/T= constant, did not hold over the range of large molecular weight. As for binary systems, it was shown that diffusion coefficients at constant molecular weight of active polymer, Mp1, in inactive base polymer of molecular weight, Mp2, were proportional to M-1.7p2 when Mp2 was smaller than a critical molecular weight for diffusion, MD, beyond which diffusion coefficients were constant. It was also shown that diffusion coefficients were proportional to M-1.0p1 in the range of this work.

THE DIFFUSION OF POLYSTYRENE IN DIFFERENT SOLVENTS

The variation of the diffusion coefficient of polystyrene with molecular weight in bromobenzene, toluene, and methyl ethyl ketone, obtained with a modified Northrop cell, obeyed the relation 1/D = AMε where A and ε are empirical constants. The decrease in the exponent ε with increasing molecular weight agrees qualitatively with the predictions of Debye and Bueche. Both the exponent and the ratio of the diffusion coefficients of a low to high molecular weight sample increased in better solvents, indicating that in such solvents the polystyrene molecules are elongated. Using this ratio as a criterion of solvent power, there is good agreement with the results of swelling and precipitation studies. The decrease in the diffusion coefficient – solvent viscosity product for a low and a high molecular weight polymer in good solvents suggests an increase in the degree of solvation of the polymer. The variation of this product with solvent composition in solvent mixtures indicates the existence of selective solvation by the good solvent. The activation energies of diffusion were of the order of 3 kcal. for both high and low molecular weight polymers in good and poor solvents. This supports Eyring's theory of segment flow for polymer diffusion.