Evidence for Viscoelastic Effects in Surface Capillary Waves of Molten Polymer Films

Jiang, Zhang; Kim, Hyun-Jung; Jiao, Xuesong; Lee, H.; Lee, Y.-J.; Byun, Youngsuk; Song, Sanghoon; Eom, Daeyong; Li, C.; Rafailovich, Miriam; Lurio, Laurence; Sinha, Sunil K.

doi:10.1103/physrevlett.98.227801

Cited by 76 publications

(105 citation statements)

References 24 publications

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“…In a reversal of the above observations, as the molecular mass of matrix PS chains further increases, the AuPS particles become more concentrated in the trenches (K > 1), whereas the matrix polymer chains segregate into the mesas due to more significant entropic penalty under confinement. It should be noted, however, that, in the case of ultrathin trench confinement (i.e., h 2 ≈ 2R g,PS ), only partial depletion of matrix PS chains was observed, as the mobility of polymer chains was significantly suppressed beyond practical equilibration times (27).…”

Section: Resultsmentioning

confidence: 99%

Entropy-driven segregation of polymer-grafted nanoparticles under confinement

Zhang

Lee

Stafford

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The modification of nanoparticles with polymer ligands has emerged as a versatile approach to control the interactions and organization of nanoparticles in polymer nanocomposite materials. Besides their technological significance, polymer-grafted nanoparticle (PGNP) dispersions have attracted interest as model systems to understand the role of entropy as a driving force for microstructure formation. For instance, densely and sparsely grafted nanoparticles show distinct dispersion and assembly behaviors within polymer matrices due to the entropy variation associated with conformational changes in brush and matrix chains. Here we demonstrate how this entropy change can be harnessed to drive PGNPs into spatially organized domain structures on submicrometer scale within topographically patterned thin films. This selective segregation of PGNPs is induced by the conformational entropy penalty arising from local perturbations of grafted and matrix chains under confinement. The efficiency of this particle segregation process within patterned mesa−trench films can be tuned by changing the relative entropic confinement effects on grafted and matrix chains. The versatility of topographic patterning, combined with the compatibility with a wide range of nanoparticle and polymeric materials, renders SCPINS (soft-confinement pattern-induced nanoparticle segregation) an attractive method for fabricating nanostructured hybrid films with potential applications in nanomaterial-based technologies.polymer thin film | polymer-grafted nanoparticle | entropy | confinement | topographic pattern T he dispersion and organization of nanoparticles in polymeric matrices are important to improve the properties of polymer nanocomposite materials (1, 2). Polymer-grafted nanoparticles (PGNPs) have attracted much attention in this regard due to their enhanced miscibility and versatility of assembled structures in polymeric materials via interacting grafted polymer layers (3, 4). The cloaking of nanoparticles by densely grafted polymer layers with the same chemical composition as the matrix leads to an "athermal" particle−polymer blend where entropic interactions dominate the thermodynamics of the system (5). Selective segregation of PGNPs at the interface or center of phase-separated block copolymer microdomains depends on the interplay between conformational and translational entropy of the system (6, 7). Considering the significant contribution of entropy in directed nanostructure formation (8, 9), entropic interactions have the potential to tailor the organization of PGNPs within a chemically identical polymer matrix, which is not achievable by conventional techniques (10, 11).The entropic effects can be magnified by confining PGNPs in thin-film geometries. Under confinement, the conformation of the grafted chains is altered, and the associated entropic penalty could drive directional migration of PGNPs and potentially generate visually ordered microstructures. To illustrate this concept, we introduce lateral confinement contrast by topographi...

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Section: Resultsmentioning

confidence: 99%

Entropy-driven segregation of polymer-grafted nanoparticles under confinement

Zhang

Lee

Stafford

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…A couple of the remarkable studies will be reviewed here. The overdamped capillary waves of polystyrene films are observed by Kim et al 60) and Jiang et al, 61,62) and they discussed the relation between the mobility of the polymer chains and the thickness of the film. Madsen et al observed the dispersion relation of the capillary waves on liquid surface near the transition point from oscillating to overdamped behavior.…”

Section: X-ray Photon Correlation Spectroscopymentioning

confidence: 93%

Surface and Interface Analyses of Polymer Brushes by Synchrotron Radiation

et al. 2013

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In the present review, we focus on the characterization of polymer brushes by quantum beam, which is regarded as a promising probe of surface and interface analysis. The polymer brushes were prepared on various shapes of surface, and proved to be benefit to various applications. Among them, the polymer brushes grafted on sphere nanoparticles and flat substrates are investigated as representative cases. The static structure of polymer brushes, especially the chain dimension of polymer brushes grafted on nanoparticles and a flat substrate, have been studied by small angle X-ray scattering (SAXS) and neutron reflectivity (NR), respectively. The microscopic dynamical properties of polymer brushes are also expected to be revealed by quantum beam. X-ray photon correlation spectroscopy (XPCS), a technique using a coherent X-ray, is one of the promising methods for microscopically understanding of dynamical properties of polymer brushes. Some of our recent studies about dynamical behavior of polymer brush immobilized nanoparticle by XPCS are also presented.

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“…[1][2][3][4][5][6][7][8][9][10][11] At third-generation synchrotrons it is nowadays possible to produce intense x-ray beam with a high degree of coherence. The scattered intensity distribution of such an x-ray beam coming from a rough surface provides a speckle pattern due to destructive and constructive interference.…”

Section: Introductionmentioning

confidence: 99%

Effects of partial coherence on correlation functions measured by x-ray photon correlation spectroscopy

Gutt¹,

Ghaderi

Tolan

et al. 2008

Phys. Rev. B

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We present a rigorous description of the effects of partial coherence and detector resolution on intensity autocorrelation functions as they can be measured by x-ray photon correlation spectroscopy ͑XPCS͒. Based on the Huygens-Fresnel propagation law and on the first Born approximation, we derive a general expression for the normalized intensity autocorrelation function. We calculate how the mutual coherence function of the x-ray beam propagates from an aperture to the sample and how it propagates after the scattering process to the detector area and consequently influences the intensity autocorrelation function. We illustrate our calculation with examples of XPCS intensity autocorrelation functions of liquid surfaces calculated for grazing incidence geometry.

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Evidence for Viscoelastic Effects in Surface Capillary Waves of Molten Polymer Films

Cited by 76 publications

References 24 publications

Entropy-driven segregation of polymer-grafted nanoparticles under confinement

Entropy-driven segregation of polymer-grafted nanoparticles under confinement

Surface and Interface Analyses of Polymer Brushes by Synchrotron Radiation

Effects of partial coherence on correlation functions measured by x-ray photon correlation spectroscopy

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