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Chain Orientation in Block Copolymers Exhibiting Cylindrically Confined Crystallization
1Princeton Materials Institute, Princeton University, Princeton, New Jersey 08544.
Macromolecules
|July 29, 1998
Summary
Crystal stem orientation in diblock copolymers depends on chain mobility. Faster diffusion leads to perpendicular alignment, while limited mobility causes tilting for better amorphous material accommodation.
Area of Science:
- Polymer Science
- Materials Science
- Crystallography
Background:
- Diblock copolymers form ordered microdomains in the melt.
- Crystallization within these microdomains influences material properties.
- Understanding crystal orientation is key to controlling morphology.
Purpose of the Study:
- Investigate crystal stem orientation in diblock copolymers.
- Determine the effect of chain mobility on crystal alignment within cylindrical microdomains.
- Compare materials with differing chain diffusion characteristics.
Main Methods:
- X-ray scattering on flow-aligned diblock copolymer specimens.
- Analysis of ethylene-b-(3-methyl-1-butene) and ethylene-b-(vinylcyclohexane) diblock copolymers.
- Characterization of crystallization behavior under varying chain mobility conditions.
Main Results:
- Crystallization is confined to cylindrical microdomains in all studied diblock copolymers.
- Preferential crystal alignment is observed within semicrystalline cylinders.
- Crystal stem orientation varies with chain diffusion ability: perpendicular alignment at high mobility, tilted stems at limited mobility.
Conclusions:
- Chain mobility significantly dictates crystal stem orientation in confined crystallization.
- Rapid chain diffusion allows for alignment perpendicular to cylinder axis.
- Limited chain mobility induces tilting for improved amorphous phase integration.
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