Crowding of Polymer Coils and Demixing in Nanoparticle-Polymer Mixtures

Abstract

The Asakura-Oosawa-Vrij (AOV) model of colloid-polymer mixtures idealizes nonadsorbing polymers as effective spheres that are fixed in size and impenetrable to hard particles. Real polymer coils, however, are intrinsically polydisperse in size (radius of gyration) and may be penetrated by smaller particles. Crowding by nanoparticles can affect the size distribution of polymer coils, thereby modifying effective depletion interactions and thermodynamic stability. To analyse the influence of crowding on polymer conformations and demixing phase behaviour, we adapt the AOV model to mixtures of nanoparticles and ideal, penetrable polymer coils that can vary in size. We perform Gibbs ensemble Monte Carlo simulations, including trial nanoparticle-polymer overlaps and variations in radius of gyration. Results are compared with predictions of free-volume theory. Simulation and theory consistently predict that ideal polymers are compressed by nanoparticles and that compressibility and penetrability stabilise nanoparticle-polymer mixtures.

18 pages, 4 figures

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Cited by in corpus (5)

• Polymer Crowding and Shape Distributions in Polymer-Nanoparticle Mixtures
• Depletion-Induced Forces and Crowding in Polymer-Nanoparticle Mixtures: Role of Polymer Shape Fluctuations and Penetrability
• Ionic Size Effects on the Poisson-Boltzmann Theory
• Influence of Solvent Quality on Conformations of Crowded Polymers
• Influence of Solvent Quality on Depletion Potentials in Colloid-Polymer Mixtures