Pathways to Macroscale Order in Nanostructured Block Copolymers

Polymeric materials undergo dramatic changes in orientational order in response to dynamic processes, such as flow. Their rich cascade of dynamics presents opportunities to create and combine distinct alignments of polymeric nanostructures through processing. In situ rheo-optical measurements comple...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 1997-08, Vol.277 (5330), p.1248-1253
Main Authors: Chen, Zhong-Ren, Kornfield, Julia A., Smith, Steven D., Grothaus, Jeffrey T., Satkowski, Michael M.
Format: Article
Language:English
Subjects:
Block copolymers
Colloids
Copolymers
Frontiers in Materials Science
High frequencies
Macromolecules
Materials
Materials science
Morphology
Morphology (Biology)
Nanostructures
Physics
Polymers
Trajectories
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Summary:Polymeric materials undergo dramatic changes in orientational order in response to dynamic processes, such as flow. Their rich cascade of dynamics presents opportunities to create and combine distinct alignments of polymeric nanostructures through processing. In situ rheo-optical measurements complemented by ex situ x-ray scattering reveal the physics of three different trajectories to macroscopic alignment of lamellar diblock copolymers during oscillatory shearing. At the highest frequencies, symmetry arguments explain the transient development of a bimodal texture en route to the alignment of layers parallel to the planes of shear. At lower frequencies, larger-scale relaxations introduce rearrangements out of the deformation plane that permit the formation of lamellae perpendicular to the shear plane. These explain the change in the character of the pathway to parallel alignment and the emergence of perpendicular alignment as the frequency decreases.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.277.5330.1248