How stable are amphiphilic dendrimers at the liquid–liquid interface?

Cheung, David L.; Carbone, Paola

doi:10.1039/c2sm27246f

Cited by 19 publications

(19 citation statements)

References 39 publications

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“…This simple model is able to reproduce interfacial effects like capillary waves and nanoparticle adsorption and it has been successfully used to investigate effects at liquidliquid interfaces with and without additional components. 14,18,[37][38][39] For a NP we use a large spherical particle as core onto which the first monomer of the polymer chains are grafted. The core and first monomers are treated as a rigid unit.…”

Section: Model and Numerical Detailsmentioning

confidence: 99%

“…16,17 In particular, recent measurements of PEG-grafted nanoparticles reported adsorption energies of the order of 1000k B T , 17 indicating strong interfacial trapping. Recent simulations of dendrimers 18 have also shown that these can have adsorption energies comparable to nanoparticles; indeed in many cases the adsorption strength is higher for dendrimers due to their ability to change conformation at the interface to maximise the decrease in interfacial free energy and the interactions between the monomers and their preferred solvent. In the case of core-shell nanoparticles the polymer shell around the NP core may similarly deform at the interface, depending on the solvation quality of the liquids with regard to the polymers.…”

Section: Introductionmentioning

confidence: 99%

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Conformations and Effective Interactions of Polymer-Coated Nanoparticles at Liquid Interfaces

Schwenke¹,

Isa²,

Cheung

et al. 2014

Langmuir

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We investigate conformations and effective interactions of polymer-coated nanoparticles adsorbed at a model liquid-liquid interface via molecular dynamics simulations. The polymer shells strongly deform at the interface, with the shape governed by a balance between maximizing the decrease in interfacial area between the two solvent components, minimizing unfavorable contact between polymer and solvent, and maximizing the conformational entropy of the polymers. Using potential of mean force calculations, we compute the effective interaction between the nanoparticles at the liquid-liquid interface. We find that it differs quantitatively from the bulk and is significantly affected by the length of the polymer chains and by the solvent quality. Under good solvent conditions, the effective interactions are always repulsive and soft for long chains. The repulsion range decreases as the solvent quality decreases. In particular, under poor solvent conditions, short chains may fail to induce steric repulsion, leading to a net attraction between the nanoparticles, whereas with long-enough chains the effective interaction potential may feature an additional repulsive shoulder at intermediate distances.

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Section: Model and Numerical Detailsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Conformations and Effective Interactions of Polymer-Coated Nanoparticles at Liquid Interfaces

Schwenke¹,

Isa²,

Cheung

et al. 2014

Langmuir

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“…Moreover, we seek a relation which could predict the tendency of a polymer to diffuse into one of the two solvents as a function of its molecular weight and solvent quality. As in previous work 17 we use molecular dynamics simulations employing a bead-spring representation of the polymer and model the solvent as a binary Lennard-Jones mixture. Different lengths of linear polymers are studied in order to investigate the effect of molecular weight on the adsorption strength.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of linear and star polymers at fluid interfaces

2015

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Performing molecular dynamics simulations on model systems we study the structural changes and thermodynamic stability of polymers of varying topology (linear and starshaped) at interface between two liquids. We find that homopolymers are attracted to the interface in both good and poor solvent conditions showing that they are surface active molecules even though not amphiphilic. In most cases changing polymer topology had only a minor effect on the desorption free energy. A noticeable dependence on polymer topology is only seen for relatively high molecular weight polymers at interface between two good solvents. Examining separately the enthalpic and entropic components of the desorption free energy suggests that its largest contribution is the decrease in the interfacial free energy caused by the adsorption of the polymer at the interface. Finally we propose a simple method to qualitatively predict the trend of the interfacial free energy as a function of the polymer molecular weight.2

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“…Using a CG model, the adsorption free energies for the class-II hydrophobins HFBI and HFBII at a water-octane interface were calculated [93] using steered molecular dynamics simulations. These were both found to have adsorption free energies of the order of 60-100 kcal mol −1 , values similar to those of synthetic nanoparticles [94] and polymers [95]. The two proteins were found to have different affinities for the two solvent components, with HFBII slightly favouring the water and HFBI the oil, which can be rationalised by differences in the sizes of the hydrophobic patches.…”

Section: Hydrophobin Behaviour At Fluid (Air-water or Oil-water) Intementioning

confidence: 77%

Molecular Dynamics Simulation of Protein Biosurfactants

Cheung

Samantray

2018

Colloids and Interfaces

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Surfaces and interfaces are ubiquitous in nature and are involved in many biological processes. Due to this, natural organisms have evolved a number of methods to control interfacial and surface properties. Many of these methods involve the use of specialised protein biosurfactants, which due to the competing demands of high surface activity, biocompatibility, and low solution aggregation may take structures that differ from the traditional head–tail structure of small molecule surfactants. As well as their biological functions, these proteins have also attracted interest for industrial applications, in areas including food technology, surface modification, and drug delivery. To understand the biological functions and technological applications of protein biosurfactants, it is necessary to have a molecular level description of their behaviour, in particular at surfaces and interfaces, for which molecular simulation is well suited to investigate. In this review, we will give an overview of simulation studies of a number of examples of protein biosurfactants (hydrophobins, surfactin, and ranaspumin). We will also outline some of the key challenges and future directions for molecular simulation in the investigation of protein biosurfactants and how this can help guide future developments.

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How stable are amphiphilic dendrimers at the liquid–liquid interface?

Cited by 19 publications

References 39 publications

Conformations and Effective Interactions of Polymer-Coated Nanoparticles at Liquid Interfaces

Conformations and Effective Interactions of Polymer-Coated Nanoparticles at Liquid Interfaces

Thermodynamics of linear and star polymers at fluid interfaces

Molecular Dynamics Simulation of Protein Biosurfactants

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