Comparison of methods for the determination of diffusion coefficients of polymers in dilute solutions: The influence of polydispersity

Mes, E.P.C.; Kok, Wim Th.; Poppe, H.; Tijssen, R.

doi:10.1002/(sici)1099-0488(19990315)37:6<593::aid-polb11>3.0.co;2-n

Cited by 45 publications

(49 citation statements)

References 31 publications

(17 reference statements)

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“…[18,41] These predictions are in satisfactory agreement with reported experimental results. [42][43][44] Diffusion measurements for slightly interacting polymers in the molten state and concentrated polymer solutions have been reported to be approximately consistent with the reptation model, which predicts that b ¼ 2 in Equation (3) for polymers with a MW above a critical value, M e , which is the molecular weight of the polymer chain between entanglements. [6,16,18,45] For short-chain polymers with a MW below M e , diffusion can be modeled successfully by considering a Rouse-like motion of monomer beads connected by entropic springs.…”

Section: Effect Of Molecular Weight Of Peg On the Interdiffusion Betwmentioning

confidence: 99%

“…However, the data for the low-MW PVP grades (M n 12 000 g Á mol À1 ) are fitted satisfactorily by a linear function ( Figure 11, solid line, R 2 ¼ 0.999) whose slope provides b ¼ 0.50, which is consistent with Zimm's model (1/2 < b 3/5) and similar experimental results for the diffusion of other polymers in good solvents. [42][43][44] It follows from the above analysis that the D 2 * value obtained for the high-MW PVP (M n ¼ 360 000 g Á mol À1 ) is most likely overestimated and is more characteristic of PVP with M n % 100 000 g Á mol À1 (shown by arrows in Figure 11). Such overestimation may be due to a broad molecular-weight distribution in the PVP samples used in this work (Table 1), which could lead to an enhanced emphasis on diffusion of polymer fractions with lower molecular weight towards neat PEG, especially for PVP samples with high average MW.…”

Section: The Effect Of the Molecular Weight Of Pvp On The Interdiffusmentioning

confidence: 99%

“…Such polydispersity has been shown to affect appreciably the precision one can estimate polymer diffusion coefficients in dilute solutions with. [44] It has also been shown that the degree of polymerization of high-MW PVP (K90 grade in Table 1) is reduced slowly upon storage, [23] and this may lead to an apparent increase in diffusivity. Finally, errors in estimating D 2 * may have arisen from polynomial extrapolation.…”

Section: The Effect Of the Molecular Weight Of Pvp On The Interdiffusmentioning

confidence: 99%

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Impact of Molecular Weight on Miscibility and Interdiffusion between Poly(N‐vinyl pyrrolidone) and Poly(ethylene glycol)

Bairamov

Чалых

Feldstein

et al. 2002

Macro Chemistry & Physics

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Miscibility and mutual diffusion between poly(N‐vinylpyrrolidone) (PVP) and short‐chain poly(ethylene glycol)s (PEGs) of different molecular weight were studied by optical wedge microinterferometry (WMI). The PVP Mn varied from 1 300 to 360 000 g · mol−1, whereas that of PEG ranged from 200 to 6 000 g · mol−1. Photographs of interference patterns measured at λ = 546 nm with an optical microscope were used to observe the PVP/PEG interface. PVP blends with short‐chain PEG fractions, ranging in molecular weight from 200 to 1 500 g · mol−1, were found to be fully miscible above the temperatures of PEG fusion, whereas an increase in the molecular weight of up to 3 000 g · mol−1 renders the two polymers completely immiscible. Successive photographs of interference patterns (the interferogram of the contact interface between PEG6000 (left) and PVP is shown in the Figure) were used to determine composition‐distance profiles and to calculate the composition‐dependent mutual diffusion coefficient in miscible PVP/PEG blends. It was shown that the effects of PVP molecular weight are in reasonable agreement with those observed for other compatible polymer systems. In contrast to PVP behavior, the effects of PEG molecular weight indicate appreciable contribution of hydrogen bonding of terminal hydroxyl groups in short PEG chains to the miscibility and diffusivity behavior in the PVP/PEG system. The difference in the effects of PEG and PVP chain lengths is ascribed to hydrogen bonding between PEG terminal hydroxyl groups with carbonyl side groups of repeat units in PVP macromolecules and ether oxygens in the PEG chains. Interferogram of the contact interface between PEG 6000 (left) and PVP. Magnification: 60‐fold.magnified imageInterferogram of the contact interface between PEG 6000 (left) and PVP. Magnification: 60‐fold.

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Section: Effect Of Molecular Weight Of Peg On the Interdiffusion Betwmentioning

confidence: 99%

Section: The Effect Of the Molecular Weight Of Pvp On The Interdiffusmentioning

confidence: 99%

Section: The Effect Of the Molecular Weight Of Pvp On The Interdiffusmentioning

confidence: 99%

See 1 more Smart Citation

Impact of Molecular Weight on Miscibility and Interdiffusion between Poly(N‐vinyl pyrrolidone) and Poly(ethylene glycol)

Bairamov

Чалых

Feldstein

et al. 2002

Macro Chemistry & Physics

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“…The size of these structures in solution was calculated from the related diffusion coefficient using the Stokes-Einstein equation [28].…”

Section: Dynamic Light Scatteringmentioning

confidence: 99%

Highly Regular Polyampholytic Structures Adsorbed Directly from Solution

Mahltig

Müller‐Buschbaum

Wolkenhauer

et al. 2001

Journal of Colloid and Interface Science

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This article concerns the adsorption of the diblock polyampholyte poly(methacrylic acid)-blockpoly((dimethylamino)ethyl methary-late) (PMAA-b-PDMAEMA) from aqueous solution on silicon substrates. The investigated polyampholyte is characterized by a small molecular weight around 15,000 g/mol and a big positively charged PDMAEMA block. The adsorbed amount determined by ellipsometry was str ongly influenced by the pH of the adsorption solution. Using dynamic light scattering polyampholytic structures with diameters around 50 nm were found in aqueous solution. The hydrodynamic diameter was hardly affected by changing the pH of the polymer solution. Analogous regular structures were also found by scanning force microscopy (SFM) and grazing incidence, small angle X-ray scattering (GISAXS) at the silicon surface after the adsorption process. While SFM provides a topographical image of a small part of the adsorbed polyampholytic layer; GISAXS was used to get a statistical description of the lateral surface structures. The adsorbed structures were highly regular and their sizes were nearly pH independent over a lar ge pH region. Only directly at the isoelectric point of the polyampholyte larger adsorbed structures were observed. Compared with earlier investigated PMAA-b-PDMAEMA systems we are now able to prepare highly regular polyampholytic structures at silicon surfaces. There are two kinds of interactions for the adsorbed micelles. First, the charged block of the chains is directly attracted to the substrate via electrostatic interactions, while the uncharged part of the chains is only hydrophobically attracted via the hydrophobic core of the adsorbed micelle.

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“…The latter can be achieved via concentration titration methods [6][7][8][9] or from a single measurement [10]. Mutual diffusion refers to the fluxes of solute and solvent molecules produced by changes or gradients in the concentration of the solution.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Comparisons of the Concentration-Dependent Diffusion Coefficients from Dynamic Light Scattering and Taylor Dispersion Analysis

Latunde-Dada¹

2016

J Anal Bioanal Tech

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Dynamic Light Scattering and Taylor Dispersion Analysis are two methods employed for the measurement of the diffusion coefficients and interaction parameters of solutes. For self-associating solutes, the interaction parameter provides a measure for the degree of association and hence the stability of the solutes. Due to the characteristics, peculiar to each method, the measured values are weighted averages and are therefore different from the intrinsic or unweighted values. In this paper, using a simple model for self-association, theoretical expressions for the DLS, TDA and intrinsic diffusion coefficients are derived for self-associating solutes. The corresponding interaction parameters are also derived and compared. As expected, at low concentrations, it was found that the DLS gives higher diffusion coefficients than TDA and vice versa at high concentrations. More interestingly, points of inflection were found in the DLS and TDA diffusion coefficient-concentration curves which imply the presence of minima in measured interaction parameters with the TDA minimum occurring at a lower concentration than for DLS. These are absent in the intrinsic curves. Furthermore, it was found that whilst the intrinsic interaction parameter tends to a non-zero value in the limit of low concentrations, the measured interaction parameters vanish. These trends are important for the interpretation of the results obtained from both measurement methods especially when compared to the intrinsic values. With the interaction parameter being increasingly used as a measure of stability, consideration of these expected trends could prove valuable for explaining experimental data measured at low concentrations. Furthermore, they could prove important when comparisons are made between results from the two measurements which are increasingly being used as orthogonal methods for protein analysis.

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Comparison of methods for the determination of diffusion coefficients of polymers in dilute solutions: The influence of polydispersity

Cited by 45 publications

References 31 publications

Impact of Molecular Weight on Miscibility and Interdiffusion between Poly(N‐vinyl pyrrolidone) and Poly(ethylene glycol)

Impact of Molecular Weight on Miscibility and Interdiffusion between Poly(N‐vinyl pyrrolidone) and Poly(ethylene glycol)

Highly Regular Polyampholytic Structures Adsorbed Directly from Solution

Theoretical Comparisons of the Concentration-Dependent Diffusion Coefficients from Dynamic Light Scattering and Taylor Dispersion Analysis

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