Mean-field models of structure and dispersion of polymer-nanoparticle mixtures

Ganesan, Venkat; Ellison, Christopher J.; Pryamitsyn, Victor

doi:10.1039/b926992d

Cited by 113 publications

(78 citation statements)

References 176 publications

(293 reference statements)

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“…9, which is significantly larger, simply because the latter is the result of integrated pair correlation functions and incorporates long range density fluctuations in surrounding "shells". It has been previously suggested that many-body effects may be responsible for increased immiscibility of smaller colloids due to overlapping many-bodied polymer depletion layers [22,23], however in this work we posit that many-body depletion on a monomeric level is a more satisfactory explanation, given that in the protein limit, polymeric depletion effects are felt at distances on the order of the polymer mesh's correlation length which is much smaller than the polymer's overall dimensions. This is supported by the observation that the locations of structural features collapse only when the abscissa is linearly shifted by the monomer diameter (reduced distance, l), suggesting that there is an underlying effect at this length scale.…”

Section: Than 1 K B T Along the Opposite Branch (Open Symbols)mentioning

confidence: 41%

“…These clearly showed that for athermal systems with monomer-monomer excluded volumes, critical densities for d < 0.25 collapse to a uniform master curve under rescaling arguments; however, for d ≥ 0.25 at identical q r , the solutions start demixing at much lower concentrations. McMillan-Mayer-type approaches have suggested this may be due to many-body effects [22,23], but to our knowledge simulations supporting this claim have not yet been performed in the protein limit. In Ref.…”

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confidence: 89%

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Structure of phase-separated athermal colloid-polymer systems in the protein limit

2013

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Structural features of phase separated athermal colloid-polymer mixtures in the so-called "protein limit," where polymer chain dimensions exceed those of the colloid, are investigated using grand canonical Monte Carlo simulations on a fine lattice. Previous work [N. A. Mahynski, et al. Phys. Rev. E 85, 051402 (2012)] has shown that this model accurately captures the phase behavior of experimental systems, and that colloids with sufficiently small diameters, σc, relative to that of the monomeric segments, σs, phase separate more readily than their large-diameter counterparts. In the present study, we directly connect colloid and polymer structure with their phase behavior by investigating these solutions along their binodal curves; we also explore the role of colloid surface curvature in destabilizing such solutions. Our findings suggest that simple consideration of an additional depletion radius, on the order of the σs, leads to a quantitatively accurate prediction of the division between stable and unstable ranges of d = σs/σc. We compare these results to continuum models with different bonding potentials between monomer segments in order to elucidate the significance of the lattice model's bond fluctuations and inherently coarse colloid surface. In a number of cases, the continuum models deviate both qualitatively and quantitatively from the lattice results, but the binodals of the continuum models are presently not known, making a strong conclusion about these differences impossible.

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Section: Than 1 K B T Along the Opposite Branch (Open Symbols)mentioning

confidence: 41%

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confidence: 89%

Structure of phase-separated athermal colloid-polymer systems in the protein limit

2013

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“…Mechanisms of controlling the state of particle aggregation in these complex mixtures remain elusive and poorly understood [6]. Conceptual frameworks for achieving good dispersion generally rely on chemically or physically bound polymer layers [7,8] to induce a repulsive interparticle potential of mean force between nanoparticles [9,10]. Nonetheless, understanding the nature of, and what controls, the structure and properties of these layers remains an outstanding challenge in soft matter of broad importance in polymer science, colloid science, and even biological systems.…”

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confidence: 99%

Multiscale Structure, Interfacial Cohesion, Adsorbed Layers, and Thermodynamics in Dense Polymer-Nanoparticle Mixtures

2011

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We establish the existence and size of adsorbed polymer layers in miscible dense nanocomposites and their consequences on microstructure and the bulk modulus. Using contrast-matching small-angle neutron scattering to characterize all partial collective structure factors of polymers, particles, and their interface, we demonstrate qualitative failure of the random phase approximation, accuracy of the polymer reference site interaction model theory, ability to deduce the adsorbed polymer layer thickness, and high sensitivity of the nanocomposite bulk modulus to interfacial cohesion. DOI: 10.1103/PhysRevLett.107.225504 PACS numbers: 61.46.Df, 61.05.fg, 61.41.+e Particle aggregation in concentrated polymer solutions, melts, and cross-linked elastomers profoundly alters the mechanical, optical, and electrical properties of nanocomposites [1][2][3][4][5]. Mechanisms of controlling the state of particle aggregation in these complex mixtures remain elusive and poorly understood [6]. Conceptual frameworks for achieving good dispersion generally rely on chemically or physically bound polymer layers [7,8] to induce a repulsive interparticle potential of mean force between nanoparticles [9,10]. Nonetheless, understanding the nature of, and what controls, the structure and properties of these layers remains an outstanding challenge in soft matter of broad importance in polymer science, colloid science, and even biological systems. Obstacles limiting progress include (i) developing experimental tools and physics-based strategies for measuring and controlling the material-specific strength of polymer segments and particle surface attraction, (ii) differentiating polymer segments adsorbed on the nanoparticle surface from bulk polymer in the dense polymer solutions or melts, and (iii) measuring the packing structure of both segments and particles over a wide range of length scales and volume fractions.In this Letter, we present experimental results addressing the above issues using contrast-matching small-angle neutron scattering techniques in conjunction with carefully designed, thermodynamically stable (miscible) concentrated ternary solutions of short-chain polymers (oligomers), nanoparticles, and solvent. Measuring the intensity of scattered neutrons as a function of particle and polymer scattering contrast allows determination of all three partial collective structure factors that quantify spatially resolved segment-segment, particle-particle, and interfacial concentration fluctuations [11]. We employ this experimental knowledge to (i) determine the adsorbed layer thickness, (ii) quantitatively test at an unprecedented level the microscopic polymer reference interaction site model (PRISM) theory [12,13], and (iii) discover strong limitations of the incompressible random phase approximation (IRPA) [14]. How interfacial cohesion can qualitatively modify the effect of particle addition on the nanocomposite bulk modulus is addressed based on the experimentally validated theory.Silica nanoparticles of diameter D ¼ 40 nm are s...

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“…Many reviews for various aspects of BCP nanocomposites have been published [4,5,8,12,15,16,18,19,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. To this end, considerable progress has been made in selectively controlling the distribution and location of QD/NP into the desired BCP domains [5,12,16,24,32,42,43].…”

Section: Introductionmentioning

confidence: 99%

Enthalpy-driven selective loading of CdSe 0.75 S 0.25 nanoalloys in triblock copolymer polystyrene- b -polyisoprene- b -polystyrene

Aşkın¹,

Çeçen²,

Ünlütürk³

et al. 2016

Materials Today Communications

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a b s t r a c tCdSe 0.75 S 0.25 nanoalloys were blended with asymmetric triblock copolymer of polystyrene-bpolyisoprene-b-polystyrene(PS-SIS) in tetrahydrofuran. The fraction of styrene block varies from 14 to 22% with respect to isoprene by mass. The morphology of the copolymer cast film experiences a phase change from cylinder to lamella. CdSe 0.75 S 0.25 nanoalloys were prepared by two-phase method. The surface of the nanoalloys was capped by either oleic acid (OA) or n-tri-octylphosphonic acid (TOPO) in situ. The mean diameter of the alloyed particles is around 12 nm in both systems. The chemical nature of the nanoalloy surface was found to influence the dispersion of the particles over polymer volume. The size of the nanoalloy domains in PS is 50 nm, on average, consisting of approximately 0.7 wt% nanoalloys. However, the size of the nanoalloy domains is smaller when they are loaded into PS-SIS. The structure formation is predominantly determined by enthalpic compatibilization. Atomic force microscopy results suggest that the nanoalloys capped with TOPO sequester into PS-rich domains and enlarge the domain. On the other hand, the ones capped with OA prefer to locate in polyisoprene domains. The increase of particles over 1.0 wt% distorts the lamella structure.

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Mean-field models of structure and dispersion of polymer-nanoparticle mixtures

Cited by 113 publications

References 176 publications

Structure of phase-separated athermal colloid-polymer systems in the protein limit

Structure of phase-separated athermal colloid-polymer systems in the protein limit

Multiscale Structure, Interfacial Cohesion, Adsorbed Layers, and Thermodynamics in Dense Polymer-Nanoparticle Mixtures

Enthalpy-driven selective loading of CdSe 0.75 S 0.25 nanoalloys in triblock copolymer polystyrene- b -polyisoprene- b -polystyrene

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