Adsorption of poly(ethylene oxide) at the air-solution interface studied by neutron reflection

Rennie, A. R.; Crawford, R. J.; Lee, E. M.; Thomas, R. K.; Crowley, T.L.; Roberts, Stiles Moxley; Qureshi, M.S.; Richards, R. W.

doi:10.1021/ma00198a044

Cited by 54 publications

(44 citation statements)

References 7 publications

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“…Based on the calculated density profiles, the monolayer is thus suggested to be completed at a concentration around 0.68 mg m −2 . This surface coverage agrees almost exactly with the value of 0.7 mg m −2 obtained from neutron reflection measurement by Rennei et al 54 , and agrees also with results from surface pressure isotherm measurements at ambient temperature [61][62][63] . However, we note that slightly lower values, with a monolayer completed between 0.5 and 0.6 mg m −2 were obtained from neutron reflectometry measurements by Henderson et al 55 and Lu et al 56 .…”

Section: Density Profilessupporting

confidence: 91%

“…Although PEG/PEO is water soluble, (due to its lower surface energy compared to that of pure water) it has also been shown to form stable spread films at the water-air interface under certain circumstances [54][55][56] . The -CH 2 -O-CH 2 -component is sufficiently hydrophobic to escape from the water subphase and to form an adsorbed layer at a surface.…”

Section: General Observationsmentioning

confidence: 99%

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A coarse-grained model for polyethylene glycol in bulk water and at a water/air interface

Prasitnok

Wilson

2013

Phys. Chem. Chem. Phys.

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Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. A coarse-grained model for polyethylene glycol (PEG) in water has been developed using a combination of the iterative Boltzmann inversion (IBI) methodology and a suitable coarse-grained water potential. The combined coarse-grained model is shown to be effective in reproducing the properties of single chains in bulk water and multiple chains across a series of chain lengths and concentrations, and is transferable to PEG chains at a water/air interface. Good agreement is achieved with both experiment and reference atomistic simulations in an explicit solvent. Simulations of a single chain in aqueous solution yield a molecular weight (M W )-radius of gyration (R g ) relation that compares favourably with the reported scaling law from experiment. Simulations of multiple chains across a wide concentration range show no concentration dependence of R g , in agreement with previous atomistic simulations. The model we develop is shown to be transferable between polymer in bulk water and at a water/air interface. For interfacial simulations, PEG chains are found to spontaneously migrate to the surface and adsorb to form a thin surface layer, which thickens with increasing surface concentration. The point at which the surface is fully saturated with polymer, and the polymer layer thicknesses obtained from simulations, are both in good agreement with experimental findings. At high surface concentrations, when the surface is fully saturated with polymer, ethylene oxide (EO) segments are found to extend into the water subphase as loop and tail conformations, with this extension increasing with further increases in the surface concentration.The coarse-grained model is noted to provide very large increases in simulation speed, with equilibration times of < 1000× the reference atomistic models. We also consider a number of different coarse-grained models for water in this study, showing that the CSJ model adopted in this work [Chiu et al., J. Chem. Theory Comput. 2010, 6, 851] is far superior for studying water at a water/air surface, than many of the previous coarse-grained models of water.

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Section: Density Profilessupporting

confidence: 91%

Section: General Observationsmentioning

confidence: 99%

A coarse-grained model for polyethylene glycol in bulk water and at a water/air interface

Prasitnok

Wilson

2013

Phys. Chem. Chem. Phys.

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“…SANS experiments by Cosgrove et al [33,34] do not support the scaling predictions, but are more consistent with the SF theory. Other SANS studies by Rennie et al [36] are inconsistent with both scaling and SF predictions, while neutron reflectivity experiments of Lee et al [38,39] and Sun et al [40] have generated data consistent with the scaling predictions.…”

Section: Structure Of Equilibrium Layersmentioning

confidence: 87%

Non-equilibrium in adsorbed polymer layers

O’Shaughnessy

Vavylonis

2005

J. Phys.: Condens. Matter

123

152

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Abstract.High molecular weight polymer solutions have a powerful tendency to deposit adsorbed layers when exposed to even mildly attractive surfaces. The equilibrium properties of these dense interfacial layers have been extensively studied theoretically. A large body of experimental evidence, however, indicates that non-equilibrium effects are dominant whenever monomer-surface sticking energies are somewhat larger than kT , a common case. Polymer relaxation kinetics within the layer are then severely retarded, leading to non-equilibrium layers whose structure and dynamics depend on adsorption kinetics and layer ageing. Here we review experimental and theoretical work exploring these non-equilibrium effects, with emphasis on recent developments. The discussion addresses the structure and dynamics in non-equilibrium polymer layers adsorbed from dilute polymer solutions and from polymer melts and more concentrated solutions. Two distinct classes of behaviour arise, depending on whether physisorption or chemisorption is involved. A given adsorbed chain belonging to the layer has a certain fraction of its monomers bound to the surface, f , and the remainder belonging to loops making bulk excursions. A natural classification scheme for layers adsorbed from solution is the distribution of single chain f values, P (f ), which may hold the key to quantifying the degree of irreversibility in adsorbed polymer layers. Here we calculate P (f ) for equilibrium layers; we find its form is very different to the theoretical P (f ) for non-equilibrium layers which are predicted to have infinitely many statistical classes of chain. Experimental measurements of P (f ) are compared to these theoretical predictions.

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“…The adsorption of PEO at the air/water interface has been intensively investigated by a variety of methods like surface tension measurements [2][3][4][5][13][14][15][16][17][18], ellipsometry [3,4], surface light scattering [2,5], and neutron reflection [17,18]. In these studies equilibration problems were reported for the dilute solutions of longer chain polyethylene oxides.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of poly(ethylene oxide) at the air/water interface: A dynamic and static surface tension study

Gilányi

Varga

Gilányi

et al. 2006

Journal of Colloid and Interface Science

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Adsorption of poly(ethylene oxide) at the air-solution interface studied by neutron reflection

Cited by 54 publications

References 7 publications

A coarse-grained model for polyethylene glycol in bulk water and at a water/air interface

A coarse-grained model for polyethylene glycol in bulk water and at a water/air interface

Non-equilibrium in adsorbed polymer layers

Adsorption of poly(ethylene oxide) at the air/water interface: A dynamic and static surface tension study

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