Segregation of chain ends to polymer melt surfaces and interfaces

Zhao, Wencheng; Zhao, Xin; Rafailovich, M.; Sokolov, J.; Composto, R. J.; Smith, Steven D.; Russell, Thomas P.; Dozier, W. D.; Mansfield, T.; Satkowski, Michael M.

doi:10.1021/ma00055a026

Cited by 89 publications

(67 citation statements)

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“…The interfacial area per reacting pair is s = N/(2hF 0 ), where it is taken that the end-group concentration at the interface is twice as high as in the bulk. 46 The time necessary for a particle to explore this area by diffusion equals s/(4D) = N/(8DhF 0 ) and, since both types of reactive particles are mobile, the local diffusion time…”

Section: Simulation Technique and Modelmentioning

confidence: 99%

Simulation of End-Coupling Reactions at a Polymer−Polymer Interface: The Mechanism of Interfacial Roughness Development

Berezkin

Kudryavtsev

2010

Macromolecules

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End-coupling between immiscible melts of two monofunctionalized polymers of a same length was modeled by dissipative particle dynamics starting from a flat interface and up to the formation of a mature lamellar microstructure. Influence of the reaction rate, chain length, and incompatibility of components on the kinetics of copolymer formation and morphology development was investigated. Regimes of linear and logarithmic growth of the conversion with time were observed before the flat interface became unstable. The conditions and mechanism of interfacial roughness development were studied in detail. It was demonstrated that overcrowding the interface with the copolymer product causing its phase separation plays the main role in spontaneous interface distortion. The instability leads to autocatalytic interface growth with exponential kinetics, when each new portion of the product creates more area for further reactions. It was followed by a slower terminal regime including formation and ripening of the lamellar microstructure. The late stage kinetics of end-coupling was strongly influenced by depletion of reactants and formation of ordered product layers. At certain conditions, it became asymptotically diffusion controlled in agreement with published experimental data.

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Section: Simulation Technique and Modelmentioning

confidence: 99%

Simulation of End-Coupling Reactions at a Polymer−Polymer Interface: The Mechanism of Interfacial Roughness Development

Berezkin

Kudryavtsev

2010

Macromolecules

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“…1 Similarly in polymers, the molecular structure and thermodynamics at the surface differs from that of the bulk, leading to notably different phase behaviors near the surface. [2][3][4][5][6][7] Of considerable debate recently is the surface mobility of polymers. Computer simulations on polymer chains in a melt near an impenetrable wall indicated an enrichment of chain ends within two polymer segment lengths of the interface.…”

Section: Introductionmentioning

confidence: 99%

Studying Surface Glass-to-Rubber Transition Using Atomic Force Microscopic Adhesion Measurements

et al. 2000

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Force-distance curves were obtained using a home-built atomic force microscope (AFM) at different temperatures (T ) 30-65°C) and probe rates (f ) 31.25-50 000 Hz) on a 150 nm thick film of a model sample, poly(tert-butyl acrylate) (M w ) 148K Da, Mw/Mn ) 17, and Tg bulk ) 50°C according to DSC). The pull-off force, Fad, at which detachment between the AFM tip and the sample occurred was measured as adhesion. By limiting the loading force, F, to ∼2.5 nN, the tip penetrated by no more than 2 nm into the sample in the glassy state. Therefore, evolution of the rheological properties of the polymer at the free surface with increasing T could be studied. In the vicinity of Tg bulk , Fad was seen to increase rapidly with increasing T or decreasing f. Equivalence between T and f was found using time-temperature superposition in which, upon rescale of f by a temperature-dependent shift factor aT AFM (T), a master curve Fad(aT AFM (T) f) resulted. We showed that Fad(aT AFM (T)f) could be fully accounted for by using an approach based on fracture mechanics of viscoelastic solids. No noticeable enhancement in the surface relaxation could be deduced according to our findings.

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“…This argument was used by Mayes [13] to predict a significant depression in the surface Tg of amorphous polymers. At the same time, the fact of such enrichment has not been strongly supported experimentally [21][22][23]. Thus, the two factors, a decrease, in the entanglement density and chain end enrichment, may contribute to a noticeable depression in the surface glass transition.…”

Section: Introductionmentioning

confidence: 99%

Morphology of fractured polymer surfaces self-bonded below the glass transition temperature

Boiko

Prud’homme

1998

Mech Compos Mater

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Segregation of chain ends to polymer melt surfaces and interfaces

Cited by 89 publications

References 0 publications

Simulation of End-Coupling Reactions at a Polymer−Polymer Interface: The Mechanism of Interfacial Roughness Development

Simulation of End-Coupling Reactions at a Polymer−Polymer Interface: The Mechanism of Interfacial Roughness Development

Studying Surface Glass-to-Rubber Transition Using Atomic Force Microscopic Adhesion Measurements

Morphology of fractured polymer surfaces self-bonded below the glass transition temperature

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