FRS study of the diffusion of a block copolymer. 1. Direct determination of the anisotropic diffusion of block copolymer chains in a lamellar microdomain

Ehlich, Dietmar; Takenaka, Mikihito; Shigeru, Okamoto; Hashimoto, Takeji

doi:10.1021/ma00053a029

Cited by 60 publications

(61 citation statements)

References 4 publications

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“…The consequences of solid and fluid directions are borne out in the anisotropy of polymer diffusion 40–43. Although most studies appear to focus on the order–disorder transition region, the anisotropy becomes particularly strong at lower temperatures.…”

Section: Resultsmentioning

confidence: 99%

Diffusion, elasticity, and shear flow in self‐assembled block copolymers: A molecular dynamics study

Fraser

Denniston

Müser

2005

J Polym Sci B Polym Phys

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Self-assembled ordered structures composed of block copolymers are simulated by molecular dynamics under stress-free conditions and under shear. We address several methodological points. The system must be allowed to adjust its size to accommodate natural periods of self-assembled structures. In addition, these structures need to be capable of rotating freely under shear. An examination of the diffusion of polymer molecules in the lamellar phase reveals subdiffusion along translationally invariant directions between the ballistic and diffusive regime. The diffused distance d increases with time t as d ! t 1/3 . We also examine the possibility of mapping structures such as cylindrical phases onto particle-field types of models. Using measurements of the wavevector-dependent dynamic matrix, we show that this cannot be done with only two-body potentials. We then examine the molecular origin of shear alignment of lamellar phases. Lamellae oriented parallel to the shear direction become unstable at high shear rates when the major axis of the tensor of gyration of individual polymers forms an average angle of 458 with the lamellae. This instability can be understood in analogy to similar transitions in liquid crystals. C 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 970-982, 2005

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Section: Resultsmentioning

confidence: 99%

Diffusion, elasticity, and shear flow in self‐assembled block copolymers: A molecular dynamics study

Fraser

Denniston

Müser

2005

J Polym Sci B Polym Phys

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“…[1,2] The macroscopic properties of such systems depend not only on the local structure in the mesoscopic scale of 10 $ 100 nm but also on the long-range order on a scale of micrometers or larger. The threedimensional (3D) morphology between grain boundary regions influences the mechanical, electrical, and diffusional properties [3,4] of block copolymer. Although important, the 3D continuity of each nanodomain at the grain boundary is not trivial.…”

Section: Introductionmentioning

confidence: 99%

Three‐Dimensional Observations of Grain Boundary Morphologies in a Cylinder‐Forming Block Copolymer

Jinnai

Yasuda

Nishi

2006

Macromolecular Symposia

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Summary:The grain boundary morphology of a cylinder-forming poly(styreneblockisoprene) (SI) diblock copolymer was investigated using transmission electron microtomography (TEMT). The three-dimensional (3D) morphologies of the grain boundaries between the two grains with different orientation angle, a, were investigated. In the present study, two kinds of grain boundary morphologies, a ' 908 and a ' 1208, were examined in 3D. It was found that, in the case of a ' 908, most of the cylindrical domains bent at the grain boundary in order not to intersect each other, while the cylindrical domains were found to be smoothly connected and were continuous in the case of a ' 1208. The observed morphologies indicated that the chain conformation inside the cylindrical microdomains plays more significant role than the segmental interaction between the two blocks.

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“…A good deal is now known about the diffusion of block copolymer chains in ordered microstructures 18–24. There is a thermodynamic barrier to motion if the junction of the block copolymer must move away from the interface.…”

Section: Introductionmentioning

confidence: 99%

Domain size equilibration in sphere‐forming block copolymers

Cavicchi

Lodge

2003

J Polym Sci B Polym Phys

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The kinetics of domain size equilibration were studied for asymmetric poly(ethylene‐alt‐propylene)‐b‐poly(dimethyl siloxane) (EPDMS) and polyisoprene‐b‐poly(dimethyl siloxane) (IDMS) block copolymers in the body‐centered cubic ordered phase. Small‐angle X‐ray scattering measurements of the principal peak position (q*) were made as a function of time after temperature jumps within the ordered state. The equilibration times were remarkably long, especially on cooling and for temperatures below 100 °C. For example, after a quench to 40 °C, q* for EPDMS had not fully equilibrated even after several weeks of annealing; IDMS required several days to equilibrate at the same temperature. In contrast, a lamella‐forming EPDMS sample was able to adjust q* within the timescale of the measurements (i.e., minutes) with both heating and cooling over the same temperature range. Measurements of tracer diffusion indicated that chain mobility was not the rate‐limiting step, although differences in mobility did account for the differences between EPDMS and IDMS. Rather, the limiting step was the required reduction in the number density of spheres on cooling; the disappearance of spheres, either by evaporation or by fusion, provided a large kinetic barrier. Lamellae, however, could adjust domain dimensions simply by local displacements of individual chains. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 715–724, 2003

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FRS study of the diffusion of a block copolymer. 1. Direct determination of the anisotropic diffusion of block copolymer chains in a lamellar microdomain

Cited by 60 publications

References 4 publications

Diffusion, elasticity, and shear flow in self‐assembled block copolymers: A molecular dynamics study

Diffusion, elasticity, and shear flow in self‐assembled block copolymers: A molecular dynamics study

Three‐Dimensional Observations of Grain Boundary Morphologies in a Cylinder‐Forming Block Copolymer

Domain size equilibration in sphere‐forming block copolymers

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