Mobility profile of solvent between parallel plates

Elmgren, Hans

doi:10.1002/pol.1982.130200704

Cited by 2 publications

(2 citation statements)

References 2 publications

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“…The scaling theory is also discussed in the view of an alternative theory (1)(2)(3)(4). Besides its partly unrealistic theoretical basis, the scaling theory suffers from several weaknesses:…”

Section: Discussionmentioning

confidence: 99%

Frictional coefficients in polymer solutions and the applicability of scaling laws to experimental data

Elmgren¹

1983

J. Polym. Sci. B Polym. Lett. Ed.

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When defined in the conventional way, the relative frictional coefficient f/f0 of dissolved polymers is dependent on the method of determination used. Sedimentation and mutual diffusion‐light scattering give a common result, which by necessity differs from that obtained by self‐diffusion measurements. The difference is due to the neglect of the nonfree draining conditions in the polymer coils, causing an inadequate reference value f0 in the cases of sedimentation and mutual diffusion. The scaling theory is also discussed in the view of an alternative theory (1‐4). Besides its partly unrealistic theoretical basis, the scaling theory suffers from several weaknesses: (i) The significance of the reference frame of the studied motions is not analyzed. (ii) When the polymer concentration is increased, the original two‐phase system (swollen coils and bulk solvent) is transformed into a single‐phase system. The effect of this, in combination with the conventional definition of f and f0 used, is not analyzed in the scaling theory. (iii) No attention is drawn to the influence of the segment mobility on the concentration dependence of the studied hydrodynamic parameter.

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Section: Discussionmentioning

confidence: 99%

Frictional coefficients in polymer solutions and the applicability of scaling laws to experimental data

Elmgren¹

1983

J. Polym. Sci. B Polym. Lett. Ed.

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“…Clearly, any influence a polymer segment might exert on the rotational motion of a solvent molecule will decrease with increasing separation between the two. [16][17] Consequently, the dynamics of the solvent can be spatially inhomogeneous. Experimentally, it is difficult to isolate solvent motion as a function of distance from a polymer chain, and consequently we adopt an indirect approach, as described herein.…”

Section: Introductionmentioning

confidence: 99%

Spatial Heterogeneity of Solvent Dynamics in Multicomponent Polymer Solutions

Krahn¹,

Lodge²

1995

J. Phys. Chem.

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Oscillatory electric birefringence has been used to examine the rotational dynamics of the solvent Aroclor 1248 (A1248), in dilute and semidilute polymer solutions containing both polystyrene (PS) and poly( 1,4-butadiene) (PB) segments. Three systems were employed: an 8.0 x 104-8.0 x 104 PS-PB block copolymer, 0 I c' I 0.162 g/mL; a 40-60 wt % PS-PB random copolymer, 0 I c I 0.126 g/mL; a 50-50 wt % homopolymer blend of 7.8 x lo3 PS and 5 x lo3 PB, 0 I c I 0.251 g/mL. Measurements were performed for six temperatures ranging from -17.00 to 2.81 "C, and data were collected for frequencies from 1 Hz to 100 kHz. Previous extensive measurements of solvent rotation in homopolymer PYA1248 and PB/A1248 solutions have established that PS acts to retard, and PB to accelerate, the solvent relaxation. Thus, in the multicomponent solutions examined there is competition between the effects of the different segments, and the results of this competition give insight into the length scale associated with the influence of the polymer on the solvent dynamics. In the block copolymer and blend solutions, the distribution of solvent relaxation times is very broad, demonstrating that the solvent dynamics are spatially inhomogeneous. The results are qualitatively consistent with a combination of the separate influences of PS and PB, but in general the PB component exerts a stronger influence on the solvent. Computer simulations were employed to extract an estimate of the correlation length associated with the influence that a given polymer segment has on the solvent dynamics; the results are consistent with

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Mobility profile of solvent between parallel plates

Cited by 2 publications

References 2 publications

Frictional coefficients in polymer solutions and the applicability of scaling laws to experimental data

Frictional coefficients in polymer solutions and the applicability of scaling laws to experimental data

Spatial Heterogeneity of Solvent Dynamics in Multicomponent Polymer Solutions

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