Effect of molecular weight on the dissolution properties of polystyrene latex films

Uǧur, Şaziye; Dinc, Atilla K.; Kışlak, Yusuf

doi:10.1007/s10965-012-9943-0

Cited by 3 publications

(3 citation statements)

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“…The exponent of the power law is much smaller than the one describing the variations of the reptation time with molar mass, which is in good agreement with previous findings. 1,7 To conclude, we find that the swelling kinetics of high mass polymers is driven by the osmotic pressure gradient built-up across the gel/solution interface, leading to a diffusion of water through the polymer with a diffusion coefficient that strongly depends on polymer concentration, when concentration spans the whole range between dry and overlap concentration. The swelling yields internal stresses in the gel that, we suggest, are released by chain contraction in the Doi-Edwards tube within a short time, and not by reptation.…”

Section: How Does the Polymer Molar Mass Affect Dissolution?mentioning

confidence: 78%

“…4 The second result commonly reported in the literature is that the diffusion coefficients associated with the two different interfaces decrease with increasing polymer molar mass. 3,[5][6][7] The molar mass dependence is generally believed to result from the step of chains disentanglement that is necessary for the dissolution to be completed, 3,5 as first suggested by Brochard and De Gennes 8 in a theoretical model. However, some points are unclear, in particular the fact that the velocity of the gel/solvent interface decreases too slowly with molar mass for the dissolution step of the gel to be driven by reptation.…”

Section: Introductionmentioning

confidence: 99%

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Understanding the role of molar mass and stirring in polymer dissolution

et al. 2016

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When a dry soluble polymer is put in contact with a large quantity of solvent, it swells and forms a transient gel, and eventually, yields a dilute solution of polymers. Everyday lab experience shows that when the molar mass is large, namely tens of times larger than entanglement mass, this dissolution process is slow and difficult and may require stirring. Here, in agreement with previous results, we found that the time needed to turn a dry grain into a dilute solution is not limited by water diffusion in the glassy or semi-crystalline dry polymer, but rather by the life-time of the transient gel made of entangled chains. In addition, we shed new light on the dissolution process by demonstrating that, in contrast to theoretical predictions, the gel life-time is not governed by reptation. We show instead that swelling is simply controlled by the osmotic pressure and the gel permeability until the overlap concentration is reached within the gel. At this stage, the gel turns into a dilute solution in which polymers are dispersed by natural convection. The observed dependence of the dissolution process on the molar mass therefore originates from the molar mass dependent overlap concentration. Under stirring, or forced convection, the polymer gel disappears at a higher critical concentration that depends on the shear rate. We suggest a description of the experimental data which uses the rheological flow curves of the solutions of the considered polymer. Inversely, dissolution times of polymer powders under stirring can be inferred from classical rheological measurements of the polymer solutions at varied concentrations.

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Section: How Does the Polymer Molar Mass Affect Dissolution?mentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Understanding the role of molar mass and stirring in polymer dissolution

et al. 2016

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“…The diffusion coefficients at the surface of the thin lms are higher than in the bulk, hinting at a surface layer with enhanced mobility. Ugur and coworkers 18 analyzed the dependency of the dissolution coefficients of polystyrene in cyclohexane-toluene mixtures. The dissolution is highly inuenced by the polydispersity of the systems and decreases with increasing molecular weight.…”

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confidence: 99%

How does low-molecular-weight polystyrene dissolve: osmotic swelling vs. surface dissolution

Marcon

Vegt

2014

Soft Matter

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By means of multiscale hierarchical modeling we study the real time evolution of low-molecular-weight polystyrene, below the glass transition temperature, in contact with its solvent, toluene. We observe two concurrent phenomena taking place: (1) the solvent diffuses into the polymer by a Case II mechanism, leading to osmotic driven swelling and progressive chain dilution (inside-out mechanism); (2) polymer chains are solvated, detach from the interface and move into the solvent before the film is completely swollen (outside-in mechanism). From our simulations we conclude that, below the entanglement length, a thin swollen layer, also observed in previous experiments, forms almost instantaneously, which allows for the outside-in mechanism to start a few tens of nanoseconds after the polymer-solvent initial contact. After this initial transient time the two mechanisms are concurrent. We furthermore observe that the presence of the solvent significantly enhances the mobility of the polymer chains of the surface layer, but only in the direction parallel to the interface.

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