Temperature dependence of the virial coefficients and the chi parameter in semi-dilute solutions of PEG

Pedersen, Jan Skov; Sommer, Cornelia

doi:10.1007/b107350

Cited by 19 publications

(30 citation statements)

References 1 publication

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“…Another assumption has been done by choosing a constant Flory parameter χ. This value was measured in pure water in the semi-dilute regime [17]. AFM experiments on C-S-H substrate at full surface coverage have shown the good predictive character of the conformation model regarding the polymer layer thickness.…”

Section: The Surface Conformation Model Of Comb-like Superplasticizersmentioning

confidence: 68%

Fluidizing efficiency of comb-like superplasticizers: The effect of the anionic function, the side chain length and the grafting degree

Dalas

Pourchet

Nonat

et al. 2015

Cement and Concrete Research

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Section: The Surface Conformation Model Of Comb-like Superplasticizersmentioning

confidence: 68%

Fluidizing efficiency of comb-like superplasticizers: The effect of the anionic function, the side chain length and the grafting degree

Dalas

Pourchet

Nonat

et al. 2015

Cement and Concrete Research

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“…In a second, more precise calculation, we therefore employed the full Flory expression for the osmotic pressure,

\frac{π}{italicRT} = - \frac{1}{V_{S}^{L}} true[\ln (1 - φ_{p}) + true(1 - \frac{1}{N} true) φ_{p} + X φ_{p}^{2} true]

Integrating via the Derjaguin approximation yields a long expression, in the Supporting Information, for the cost of brush compression. Substituting the initial brush heights and a final brush height of 2 nm into this expression (along with chi = 0.4 49 ), we report the values in Table III for the relative cost of brush compression. Notably, the previous scaling as the square of PEO brush content is obscured by the improved solution thermodynamics; however, the relative compression costs are similar to the simpler second virial approach.…”

Section: Analysis and Discussionmentioning

confidence: 99%

“…Note that in obtaining these figures, the osmotic pressure is the resistance to compression, as described by Milner. 17 Rather than employing the second virial expression for osmotic pressure, we use equation 2, with χ = 0.4 49 because of the elevated segmental concentrations in a gap whose thickness is the 2 nm Debye length. While the results appear slightly less costly than penetration, the sufficient uncertainty (the actual position of the protein within the brush, and the details of its surface contour) in the calculations precludes a firm argument for penetration or compression by protein.…”

Section: Analysis and Discussionmentioning

confidence: 99%

How Bacteria Adhere to Brushy PEG Surfaces: Clinging to Flaws and Compressing the Brush

et al. 2012

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This study examined the compression of solvated polymer brushes on bioengineered surfaces during the initial stages of Staphylococcus Aureus (S. aureus) adhesion from gentle flow. A series of PEG [poly(ethylene glycol)] brushes, 7 to 17 nm in height and completely non-adhesive to proteins and bacteria, were modified by the incorporation of sparse isolated ~10 nm cationic polymer “patches” at their bases. These nanoscale regions, which lacked PEG tethers, were electrostatically attractive towards negative bacteria or proteins. S. aureus drawn to the interface by multiple adhesive patches compressed the PEG brush in the remaining contact region. The observed onset of bacterial or fibrinogen capture with increases in patch content was compared with calculations. Balancing the attraction energy (proportional to the number of patches engaging a bacterium during capture) against steric forces (calculated using the Alexander-DeGennes treatment) provided perspective on the brush compression. The results were consistent with a bacteria-surface gap on the order of the Debye length in these studies. In this limit of strong brush compression, structural features (height, persistence length) of the brush were unimportant so that osmotic pressure dominated the steric repulsion. Thus, the dominant factor for bacterial repulsion was the mass of PEG in the brush. This result explains empirical reports in the literature that identify the total PEG content of a brush as a criteria for prevention of bioadhesion, independent of tether length and spacing, within a reasonable range for those parameters. Bacterial capture was also compared to that of protein capture. It was found, surprisingly, that the patchy brushes were more protein-than bacteria-resistant. S. aureus adhesion driven by patches within otherwise protein-resistant PEG brushes was explained by the bacteria’s greater tendency to compress large areas of brush to interact with many patches. By contrast, proteins are thought to penetrate the brush at a few sites of PEO-free patches. The finding provides a mechanism for the literature reports that in-vitro protein resistance is a poor predictor of in-vitro implant failure related to cell-surface adhesion.

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“…v is the Flory parameter and is equal to 0.37 for PEG. 76 Using a broad range of PCEs characterized by size exclusion chromatography, dynamic light scattering, and small angle neuter scattering, Gelardi et al demonstrated that the above relation well captures the power law dependence on the structural parameters P, N, and n. 91 However, they indicated that depending on polydispersity the numerical prefactor may not be fully accurate. Nevertheless, when considering hydrodynamic radii, this gives quite accurate predictions for PCEs produced by graphting onto industrially produced backbones typically used for commercial products.…”

Section: Sidebar 2 Conformation Of Pces and Polymer Physicsmentioning

confidence: 99%

Molecular and submolecular scale effects of comb‐copolymers on tri‐calcium silicate reactivity: Toward molecular design

Marchon

Juilland²,

Gallucci³

et al. 2017

J Am Ceram Soc

121

110

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The impact of organic compounds on the processing and reactivity of inorganic materials has been a source of inspiration for materials scientists for decades and continues to trigger novel and innovative applications in a broad range of disciplines. However, molecular design of such compounds to reach targeted properties remains challenging, particularly for reactive and multicomponent systems. This outstanding challenge is met here by combining a model cement, hosting different coupled reactions of dissolution, nucleation and growth, together with combcopolymers that offer large and well-controlled variations of their molecular architecture. We show that silicate reactivity is affected by a combination of molecular and submolecular scale effects of these polymers. The first can be described by scaling laws from polymer physics, whereas the second involves specific chemical interactions. In particular, the ability of these polymers to hinder dissolution appears to be crucial, something for which strong experimental evidence is provided. K E Y W O R D Scalcium silicate,

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Temperature dependence of the virial coefficients and the chi parameter in semi-dilute solutions of PEG

Cited by 19 publications

References 1 publication

Fluidizing efficiency of comb-like superplasticizers: The effect of the anionic function, the side chain length and the grafting degree

Fluidizing efficiency of comb-like superplasticizers: The effect of the anionic function, the side chain length and the grafting degree

How Bacteria Adhere to Brushy PEG Surfaces: Clinging to Flaws and Compressing the Brush

Molecular and submolecular scale effects of comb‐copolymers on tri‐calcium silicate reactivity: Toward molecular design

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