Effects of a diblock copolymer on adhesion between immiscible polymers. 1. Polystyrene (PS)-PMMA copolymer between PS and PMMA

Brown, Hugh R.; Char, Kook Heon; Deline, V. R.; Green, P. F.

doi:10.1021/ma00068a014

Cited by 208 publications

(189 citation statements)

References 9 publications

(13 reference statements)

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“…Phys. 131, 064904 ͑2009͒ studies 34,35 have been done by replacing the diblock connectors that form a single stitch at the interface with multiblock connectors that form multiple stitches. Due to the fact that the connectors make multiple excursions across the interface, the areal density of stitches differs from the areal density of connectors.…”

Section: -9mentioning

confidence: 99%

“…Our results, showing a moderate increase in the tensile work with the number of stitches at the same chain length, are in better qualitative agreement with experimental results that indicate random copolymer connectors as "surprisingly effective in reinforcing polymer interfaces," but not better than diblock ͑one-stitch͒ connectors of the same length at the same connector areal density. [34][35][36][37][38][39] In the chain pull-out regime, the external work goes mainly into the stretching of the connector molecules, which does not change dramatically from the one-stitch case to the many-stitch cases. 40 When the length of each block is kept constant and the total length of the connector multiplies with the number of stitches, the adhesion strength G grows significantly mainly due to the increased length of the chains.…”

Section: -9mentioning

confidence: 99%

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Forced reptation revealed by chain pull-out simulations

Bulacu

Giessen

2009

The Journal of Chemical Physics

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We report computation results obtained from extensive molecular dynamics simulations of tensile disentanglement of connector chains placed at the interface between two polymer bulks. Each polymer chain (either belonging to the bulks or being a connector) is treated as a sequence of beads interconnected by springs, using a coarse-grained representation based on the Kremer–Grest model, extended to account for stiffness along the chain backbone. Forced reptation of the connectors was observed during their disentanglement from the bulk chains. The extracted chains are clearly seen following an imaginary “tube” inside the bulks as they are pulled out. The entropic and energetic responses to the external deformation are investigated by monitoring the connector conformation tensor and the modifications of the internal parameters (bonds, bending, and torsion angles along the connectors). The work needed to separate the two bulks is computed from the tensile force induced during debonding in the connector chains. The value of the work reached at total separation is considered as the debonding energy G. The most important parameters controlling G are the length (n) of the chains placed at the interface and their areal density. Our in silico experiments are performed at relatively low areal density and are disregarded if chain scission occurs during disentanglement. As predicted by the reptation theory, for this pure pull-out regime, the power exponent from the scaling G∝na is a≈2, irrespective of chain stiffness. Small variations are found when the connectors form different number of stitches at the interface, or when their length is randomly distributed in between the two bulks. Our results show that the effects of the number of stitches and of the randomness of the block lengths have to be considered together, especially when comparing with experiments where they cannot be controlled rigorously. These results may be significant for industrial applications, such reinforcement of polymer-polymer adhesion by connector chains, when incorporated as constitutive laws at higher time/length scales in finite element calculations.

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Section: -9mentioning

confidence: 99%

Section: -9mentioning

confidence: 99%

Forced reptation revealed by chain pull-out simulations

Bulacu

Giessen

2009

The Journal of Chemical Physics

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“…These interfaces would only exhibit high values of G c when the molecular weight of each block exceeded M e . [3][4][5][6][7][8] The low G c values measured for interfaces reinforced with unentangled diblock copolymers suggested that entanglement formation was the primary mechanism of reinforcement.…”

Section: Introductionmentioning

confidence: 99%

Model for the fracture energy of glassy polymer–polymer interfaces

Benkoski

Fredrickson

Krämer

2002

J Polym Sci B Polym Phys

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ABSTRACT:The increase in the interfacial fracture energy (G c ) with increasing interfacial width (a i ) goes through a transition at a critical value of a i that is unique to each polymer-polymer system. This transition point does not scale with the bulk entanglement spacing (d t ) for different systems, implying that the role of chain friction in reinforcing these interfaces is more important than previously thought. A theoretical model has been developed to calculate G c as a function of the interfacial stress transfer due to individual polymer chains. When including the effects of chain friction only, the model reproduces the nonuniversal behavior of G c with respect to a i /d t but yields poor fits for a i /d t Ͼ 1. The effects of entanglements are then added by calculating the fraction of entangled chains as a function of a i /d t . This contribution, although not material specific, matches the qualitative behavior of G c for large values of a i /d t . When both contributions are included in the model, excellent fits are obtained for all data sets.

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“…2 When a blend just begins to separate into one rich and the other poor domains, the width of the interface is much broader than the molecular size of the polymer; 3 in other words, smaller the width of the interface, more entanglements are formed across these interfaces which improves the mechanical properties of the blend system. 4,5 Theoretical descriptions, conversely, are quite different to describe interfaces between two unmixed domains. [6][7][8][9][10][11][12][13][14][15][16][17][18][19] The main difference can be traced back to the strength of the interactions on the scale of the monomeric units.…”

Section: Introductionmentioning

confidence: 99%

A new insight into interface widths in binary polymer blends based on ortho‐positronium lifetime studies

Ramya

Ranganathaiah

2012

J of Applied Polymer Sci

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The interface widths in two immiscible polymer blend (Poly vinyl chloride (PVC)/Polystyrene (PS)) and PVC/Ethylene Vinyl Acetate (EVA) are determined experimentally using hydrodynamic interaction approach through free volume measurement by positron annihilation lifetime spectroscopy. For comparison, the same study is performed in a miscible blend (Styrene Acrylonitrile (SAN)/Poly Methyl Methacrylate (PMMA)). The interfacial width (Dl) is evaluated from the hydrodynamic interaction (a) based on Kirkwood-Risemann theory and friction coefficient from Stokes equation. Friction at the interface of a binary blend evidences how close the surfaces of the polymer chains come or stay apart which in turn depends on the type of force/interaction at the interface. In this work, we define interface width from a different perspective of Flory-Huggins interaction approach. Measured composition dependent interface widths in the three blends studied clearly demonstrate the sensitivity of the present method. In miscible blend, high friction at the interface results in stronger hydrodynamic interaction and hence smaller interface widths (0.36-1.97 Å ), whereas weak or no interaction in immiscible blends produce wider widths (2.81-25.0 Å ).

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Effects of a diblock copolymer on adhesion between immiscible polymers. 1. Polystyrene (PS)-PMMA copolymer between PS and PMMA

Cited by 208 publications

References 9 publications

Forced reptation revealed by chain pull-out simulations

Forced reptation revealed by chain pull-out simulations

Model for the fracture energy of glassy polymer–polymer interfaces

A new insight into interface widths in binary polymer blends based on ortho‐positronium lifetime studies

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