Abstract:Static and dynamic light scattering was applied in a comprehensive study of the different modes of relaxatory motion in polystyrene-dioxane mixtures, comprising the whole range of different compositions from dilute solution to plasticized melts. For the analysis of data measured in the presence of the nearly elastic anomalous excess scattering usually encountered in concentrated solutions and the melt, a generalized Siegert relation was used. Analysis of depolarized dynamic scattering data obtained for the PS-… Show more
“…Osmotic modulus. The osmotic modulus is related to the measured time-averaged scattered light intensi-ties (I) as 20 Here R is the gas constant and R is the so-called Rayleigh ratio, which we obtained by using toluene at 20 °C as a standard: R ) [(I -I 0 )/I tol ]R tol (n s /n tol ) 2 . I 0 is the intensity scattered by the pure components which should be a weighted average of pure DOP and pure polystyrene.…”
Section: Resultsmentioning
confidence: 99%
“…While the dynamics of polymer solutions have been studied extensively by dynamic light scattering (DLS) at volume fractions below 0.1 and above 0.9, relatively few studies have been done covering the intermediate concentrations. , There are several reasons for this. One of the main ones is that this concentration regime is exceedingly demanding experimentally.…”
Solutions of polystyrene in DOP were studied as a function of the
concentration (0.2−0.9
g/mL) and temperature (−10 to +130 °C) using static and dynamic
light scattering. The concentration
and temperature dependence of the cooperative diffusion coefficient and
the osmotic modulus were
determined. The concentration and temperature dependences of the
cooperative diffusion coefficient are
explained in terms of the concentration and temperature dependence of
the osmotic modulus and the
solvent mobility. At the concentrations studied, the effect of
hydrodynamic interactions is small. Close
to the glass transition temperature the solvent mobility is the
dominant factor and can be treated in
terms of the free volume theory.
“…Osmotic modulus. The osmotic modulus is related to the measured time-averaged scattered light intensi-ties (I) as 20 Here R is the gas constant and R is the so-called Rayleigh ratio, which we obtained by using toluene at 20 °C as a standard: R ) [(I -I 0 )/I tol ]R tol (n s /n tol ) 2 . I 0 is the intensity scattered by the pure components which should be a weighted average of pure DOP and pure polystyrene.…”
Section: Resultsmentioning
confidence: 99%
“…While the dynamics of polymer solutions have been studied extensively by dynamic light scattering (DLS) at volume fractions below 0.1 and above 0.9, relatively few studies have been done covering the intermediate concentrations. , There are several reasons for this. One of the main ones is that this concentration regime is exceedingly demanding experimentally.…”
Solutions of polystyrene in DOP were studied as a function of the
concentration (0.2−0.9
g/mL) and temperature (−10 to +130 °C) using static and dynamic
light scattering. The concentration
and temperature dependence of the cooperative diffusion coefficient and
the osmotic modulus were
determined. The concentration and temperature dependences of the
cooperative diffusion coefficient are
explained in terms of the concentration and temperature dependence of
the osmotic modulus and the
solvent mobility. At the concentrations studied, the effect of
hydrodynamic interactions is small. Close
to the glass transition temperature the solvent mobility is the
dominant factor and can be treated in
terms of the free volume theory.
“…17 We have tested the adequacy of the generalized Ornstein-Zernike equation ͑7͒ by comparing the calculated S(qϭ0) with experimental data of polysty-rene dissolved in the good solvent toluene. 22 The results are displayed in Fig. 1 as a function of the chain overlap ratio / à , where à ϭ3/(4r g 3 ), and seen to agree well for several polymer concentrations.…”
Articles you may be interested inConsistent coarse-graining strategy for polymer solutions in the thermal crossover from good to θ solvent J. Chem. Phys. 139, 034901 (2013); 10.1063/1.4812691 Brownian dynamics simulations of single polymer chains with and without self-entanglements in theta and good solvents under imposed flow fields Thermal and mass diffusion in a semidilute good solvent-polymer solution
“…The time correlation function is nearly single exponential for all concentrations. No slow modes were observed in contrast to literature data of linear PS in 1,4-dioxane . The effect of the coupling reagent is recognized by the different slope (first cumulant) in the TCF in the dilute region or by the difference in the ratio of the slopes in the dilute and semidilute regimes, i.e., R h /ξ h . 2 Static (a) and dynamic (b) LS from associating and nonassociating stars: (□) TRI1; (▵) TRI2; (▿) TRI3.…”
Section: Resultsmentioning
confidence: 89%
“…No slow modes were observed in contrast to literature data of linear PS in 1,4dioxane. 18 The effect of the coupling reagent is recognized by the different slope (first cumulant) in the TCF in the dilute region or by the difference in the ratio of the slopes in the dilute and semidilute regimes, i.e., R h / ξ h . The molecular weights of the associates at a finite concentration c may be estimated from the static scattering intensity.…”
Amino-terminated three-armed polystyrene stars of narrow molecular weight distribution were prepared by anionic polymerization. The association of these star polymers with a low molecular weight dinitrophenol compound was studied by means of light scattering and ultraviolet-visible spectroscopy in the good solvent 1,4-dioxane and in the Θ solvent diethyl malonate. The concentration dependence of the scattered intensity was used to derive the increase in weight average molecular weights of the associates Mw(c) where a correction was applied that allowed the separation of the influence of repulsion forces. The experimental molecular weights were found to be smaller than predicted by the Flory-Stockmayer branching theory. Deviations are stronger for star polymers of low molecular weight, which is explained by intramolecular complex formation. No substantial difference was detected between the association in good and Θ solvents. Gel formation did not occur, and reasons are discussed.
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