Stability of Polymer Grafted Nanoparticle Monolayers: Impact of Architecture and Polymer–Substrate Interactions on Dewetting

Che, Justin; Jawaid, Ali; Grabowski, Christopher A.; Yi, Yoon-Jae; Louis, G. Chakkalakal; Ramakrishnan, Subramanian; Vaia, Richard A.

doi:10.1021/acsmacrolett.6b00772

Cited by 27 publications

(30 citation statements)

References 40 publications

(90 reference statements)

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“…The interactions between polymer-tethered particles and the substrate affect their wetting–dewetting stability. 39 Che et al 40 studied monolayers of polystyrene-grafted gold nanoparticles adsorbed on different surfaces. They showed that, with increasing polymer–surface interaction energy, the polymer “canopy” of individual particles spreads out to increase its interaction with the surface.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of Polymer-Tethered Particles on Solid Surfaces

2022

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We explore the behavior of polymer-tethered particles on solid surfaces using coarse-grained molecular dynamics simulations. Segment–segment, segment–core, and core–core interactions are assumed to be purely repulsive, while the segment–substrate interactions are attractive. We analyze changes in the internal structure of single hairy particles on the surfaces with the increasing strength of the segment–substrate interactions. For this purpose, we calculate the density profiles along the x , y , z axes and the mass dipole moments. The adsorbed hairy particles are found to be symmetrical in a plane parallel to the substrate but strongly asymmetric in the vertical direction. On stronger adsorbents, the particle canopies become flattened and the cores lie closer to the wall. We consider the adsorption of hairy nanoparticles dispersed in systems of different initial particle densities. We show how the strength of segment–substrate interactions affects the structure of the adsorbed phase, the particle–wall potential of the average force, the excess adsorption isotherms, and the real adsorption isotherms.

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Section: Introductionmentioning

confidence: 99%

Adsorption of Polymer-Tethered Particles on Solid Surfaces

2022

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“…While the macroscopic properties of these hybrids are strongly influenced by the multiscale NP organization, the intrinsic immiscibility between the inorganic (hydrophilic) NPs and the organic (hydrophobic) polymer makes it difficult to achieve and control this organization . Covalently linking polymers to the NPs to create one-component grafted nanoparticles (GNP) circumvents many of these problems. − Recently we showed that GNP membranes, with no free polymer (“matrix free”), exhibited remarkable increases in gas/condensable solute permeabilities relative to that of the neat polymer . In particular, solute permeability displayed a peak as a function of graft molecular weight, M n , at a fixed grafting density, σ.…”

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confidence: 99%

Location of Imbibed Solvent in Polymer-Grafted Nanoparticle Membranes

et al. 2018

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Membranes made purely from nanoparticles (NPs) grafted with polymer chains show increased gas permeability relative to the analogous neat polymer films, with this effect apparently being tunable with systematic variations in polymer graft density and molecular weight. To explore the structural origins of these unusual transport results, we use small angle scattering (neutron, X-ray) on the dry nanocomposite film and to critically examine in situ the structural effects of absorbed solvent. The relatively low diffusion coefficients of typical solvents (∼10 −12 m 2 /s) restricts us to thin films (≈1 μm in thickness) if solute concentration profiles are to equilibrate on the 1 s time scale. The use of such thin films, however, renders them as weak scatterers. Inspired by our nearly two decades old previous work, we address these conflicting requirements through the use of a custom designed flow cell, where stacks of 10 individual ≈1 μm thick supported films are used, while ensuring that each film is individually exposed to solvent vapor. By using isotopically labeled solvents, we study the solvent distribution within the film and show surprisingly that the solvent homogeneously swells the polymer under all conditions that we examined. These results are not anticipated by current theories, but they suggest that, at least under some conditions, the free volume increases due to the grafting of chains to nanoparticles is apparently distributed isotropically in these materials.

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“…23−25 In particular, star polymers, topologically similar to PGNPs, exhibit a strong dependence of self-diffusion coefficient on the number of chains and the degree of polymerization of branched chains, indicating that the mobility of PGNPs is expected to be significantly slower than the linear counterparts. 26,27 Therefore, the phase behavior of PGNPs in a binary mixture is closely connected to their dynamics in solutions (during film casting) as well as in melts (during post-thermal annealing). Upon annealing of the film at a temperature (T) greater than the glass-transition temperature (T g ), the perturbed chains are relaxed to the equilibrated melt with Gaussian conformation.…”

Section: ■ Introductionmentioning

confidence: 99%

“…However, in practice, the morphological evolution of constituent species depends on how we process polymer blends into bulk materials or films across a wide range of temperature and time scale because the equilibrium of polymer chains can be kinetically hindered and their relaxation time significantly deviates from the equilibrated state. For example, the as-cast linear polymer blends consisting of polystyrene (PS) and poly(methyl methacrylate) (PMMA) showed a contradict surface morphology (i.e., a formation of the PS/PMMA bilayer or the dome-like PS domain on the top of PMMA) depending on their M , as the chain mobility with high M is much rapidly reduced during spin-casting, resulting in quenched conformations. − In particular, star polymers, topologically similar to PGNPs, exhibit a strong dependence of self-diffusion coefficient on the number of chains and the degree of polymerization of branched chains, indicating that the mobility of PGNPs is expected to be significantly slower than the linear counterparts. , Therefore, the phase behavior of PGNPs in a binary mixture is closely connected to their dynamics in solutions (during film casting) as well as in melts (during post-thermal annealing).…”

Section: Introductionmentioning

confidence: 99%

Non-Equilibrium Phase Behavior of Immiscible Polymer-Grafted Nanoparticle Blends

et al. 2019

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Preferential attraction of polymer chains to the substrate [i.e., poly(methyl methacrylate) (PMMA) on the hydroxyl-terminated Si substrate] typically results in the initial phase separation of spin-cast immiscible linear polymer blends [i.e., polystyrene (PS)/PMMA] with a characteristic interfacial microstructure depending on their molecular weight. A formation of the undesired microstructure in those blends is inevitable because of the thermodynamic force driving their phase separation combined with relatively rapid dynamics in solution. In contrast, the polymer ligands, which are grafted from nanoparticles, are capable of limited segmental interactions in the presence of segmental contacts of chemically distinct chains as well as hindered mobility by interpenetration (or entanglement) and thus exhibit a homogeneous but non-equilibrium phase behavior. Here, the microstructure of the blends consisting of immiscible polymer-grafted nanoparticles (PGNPs) was identified by their neutron reflectivity, in which the scattering length density was controlled by tethering deuterated PS on silica NPs. We demonstrate that the single-phase homogeneous microstructure is attributed to a significantly reduced particle dynamics arising from the cooperative motion (or interpenetration) of polymer ligands during vitrification of PGNP films despite a relatively high degree of segregation NχS/MMA. Furthermore, the slower segmental interactions of polymer ligands promote the thermal stability of the PGNP blends in the kinetically quenched non-equilibrium state. This suggests a crucial role of polymer ligands to determine the relevant properties relying on their microstructures in a wide range of blending approaches utilizing nanoparticles and polymers.

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Stability of Polymer Grafted Nanoparticle Monolayers: Impact of Architecture and Polymer–Substrate Interactions on Dewetting

Cited by 27 publications

References 40 publications

Adsorption of Polymer-Tethered Particles on Solid Surfaces

Adsorption of Polymer-Tethered Particles on Solid Surfaces

Location of Imbibed Solvent in Polymer-Grafted Nanoparticle Membranes

Non-Equilibrium Phase Behavior of Immiscible Polymer-Grafted Nanoparticle Blends

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