A Monte Carlo Simulation of Asymmetric Random Copolymers at an Immiscible Interface

Smith, Grant D.; Russell, Thomas P.; Kulasekere, R.; Ankner, John F.; Kaiser, H.

doi:10.1021/ma951515r

Cited by 12 publications

(9 citation statements)

References 16 publications

(24 reference statements)

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“…(1) [15] qualitatively, with g SM 0.8 ergs͞cm 2 and d͑Dg͒͞df 2g SM ϳ 1.6 ergs͞cm 2 . Dg was equal to zero at f 0.57 6 0.05 rather than at f 0.5 (indicating that x AB is concentration [23] and composition [24,25] dependent). The linear increase of c͑d͒ observed here, for f .…”

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confidence: 94%

Interfacial Segregation in Disordered Block Copolymers: Effect of Tunable Surface Potentials

et al. 1997

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The response of disordered P(d-S-b-MMA) diblock copolymers to variable strength surface fields has been studied by neutron reflectivity. Surface interactions were controlled by end grafting P(S-r-MMA) random copolymers with various styrene contents onto Si substrates. The degree interfacial segregation of the block copolymer was proportional to the surface potential. A first-order transition in the degree of segregation was observed as the brush composition was varied. Conditions were found which yielded neutral boundary conditions simultaneously at the vacuum and substrate interfaces. [S0031-9007(97)03464-9] PACS numbers: 61.41. + e, 61.12.Ha

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confidence: 94%

Interfacial Segregation in Disordered Block Copolymers: Effect of Tunable Surface Potentials

et al. 1997

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“…Previous investigations have indicated that random copolymers are surprisingly effective in reinforcing polymer–polymer interfaces 1–12. The strength of such interfaces is of critical importance in a number of applications, including semiconductor packaging, fiber optics, biomedical devices, pressure sensitive adhesives, and polymer blends.…”

Section: Introductionmentioning

confidence: 99%

Effects of composition drift on the effectiveness of random copolymer reinforcement at polymer–polymer interfaces

Benkoski

Fredrickson

Krämer

2001

J Polym Sci B Polym Phys

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Random copolymer layers are surprisingly effective at reinforcing polymerpolymer interfaces. One hypothesis is that composition drift during synthesis can account for the higher than expected toughening. To test this hypothesis, we polymerized a series of poly(d-styrene-r-2-vinylpyridine) (dPS f -r-PVP 1Ϫf ) copolymers with various fractions (f ) of deuterated styrene to only 10% completion to avoid composition drift. The fracture energies (G c ) of polystyrene/dPS-r-PVP/poly(2-vinylpyridine) interfaces with relatively thick layers of dPS-r-PVP were measured. G c decreased relative to interfaces reinforced with composition-drifted dPS-r-PVP. Conversely, G c increased when two or more copolymers were blended together. In such samples, the copolymers form distinct layers with multiple interfaces characterized by the difference in f (⌬f ) between adjacent layers. We find that G c is governed by ⌬f max , the largest difference in adjacent compositions, and, therefore, by the width of the narrowest interface (w min ). G c increases strongly as w min increases from 3 to 5 nm. Remarkably, these w min values are about half the entanglement spacing in bulk polystyrene.

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“…11,12 An important goal of our work was to determine the predominant strengthening mechanism for copolymer layers coated at homopolymer joints. We deduce that the relative interactions of the copolymer with each homopolymer phase plays a role in determining the locus of fracture, and hence the apparent strength of the joint.…”

Section: Introductionmentioning

confidence: 99%

“…These results cannot adequately be explained by the "stitch" model, because random copolymers in "thick" layers cannot cross between the A and Our own study on P(S-ran-MMA) random copolymers at PS/PMMA joints parallels work being done by Brown and co-workers. 11,12 An important goal of our work was to determine the predominant strengthening mechanism for copolymer layers coated at homopolymer joints. We deduce that the relative interactions of the copolymer with each homopolymer phase plays a role in determining the locus of fracture, and hence the apparent strength of the joint.…”

Section: Introductionmentioning

confidence: 99%

Modifying a Polystyrene/Poly(methyl methacrylate) Interface with Poly(styrene-co-methyl methacrylate) Random Copolymers

et al. 1997

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Joints of polystyrene (PS) and poly(methyl methacrylate) (PMMA) modified with ∼50 nm of poly(styrene-co-methyl methacrylate) random copolymer [P(S-ran-MMA)] were investigated. Copolymers having styrene compositions of fS ) 0.48 and fS ) 0.73 were used. Transmission electron microscopy reveals that the copolymers phase separate to form a distinct layer at the joint such that there is an interface with each homopolymer. Interfacial fracture toughness measurements, using the asymmetric double cantilever beam geometry, show a strong effect of the PS to PMMA sheet thickness ratio; that is, the phase angle influences the measured interfacial toughness. Reflection infrared spectroscopy on fracture surfaces indicates that the crack propagates at or near the PS/copolymer interface for all thickness ratios and for both copolymers. In-plane crazing was not observed in front of the crack tip for these systems. Rather, strengthening appears to be exclusively a consequence of oblique crazes in the more compliant PS sheet which form at 45°or 135°relative to the crack direction. Joints modified with P(S0.73-ran-MMA) exhibit denser oblique crazes than those modified with P(S0.48-ran-MMA), resulting in a higher measured fracture toughness at all sheet thickness ratios or phase angles.

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A Monte Carlo Simulation of Asymmetric Random Copolymers at an Immiscible Interface

Cited by 12 publications

References 16 publications

Interfacial Segregation in Disordered Block Copolymers: Effect of Tunable Surface Potentials

Interfacial Segregation in Disordered Block Copolymers: Effect of Tunable Surface Potentials

Effects of composition drift on the effectiveness of random copolymer reinforcement at polymer–polymer interfaces

Modifying a Polystyrene/Poly(methyl methacrylate) Interface with Poly(styrene-co-methyl methacrylate) Random Copolymers

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