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Self-Ordering within Thin Films of Poly(olefin sulfone)s
1School of Chemistry, The Queen's University of Belfast, Belfast BT9 5AG, Northern Ireland, United Kingdom, U.K., Department of Chemistry, Humboldt University Berlin, Erieseering 42, D-10319 Berlin, Germany, and Department of Physics, University of Potsdam, Am Neuen Palais 10, D-14469 Potsdam, Germany.
Macromolecules
|July 29, 1998
Summary
Structural features in poly(olefin sulfone)s, like helical backbones and side chains, create order in films. This study explores how these polymers form ordered phases, leading to a novel homeo-planar smectic arrangement.
Area of Science:
- Polymer Science
- Materials Science
- Organic Chemistry
Background:
- Poly(olefin sulfone)s exhibit unique structural features, including helical backbones and calamitic side chains.
- Understanding how these features influence film order is crucial for materials applications.
Purpose of the Study:
- To investigate the relationship between polymer structure and film ordering.
- To characterize the ordered phases formed by copolymers and terpolymers of poly(olefin sulfone)s with cyanobiphenyl side chains.
Main Methods:
- Synthesis of copolymers and terpolymers with varying cyanobiphenyl content.
- X-ray powder diffraction to study ordered phases and layer spacing.
- Optical property measurements to determine film order (homeotropic and planar).
Main Results:
- All synthesized polymers formed ordered phases upon cooling from the melt, with a consistent layer spacing of approximately 45 Å.
- Polymers rich in eicosene sulfone residues exhibited crystalline phases, while those with higher cyanobiphenyl content formed liquid crystalline phases.
- A novel 'homeo-planar smectic' order was observed, characterized by homeotropic aromatic ordering and planar backbone ordering within a monodomain film.
- High order parameters (up to 0.63) were achieved, with cyanobiphenyl chromophores forming H aggregates, leading to observable circular dichroism.
Conclusions:
- Helical backbones and calamitic side chains in poly(olefin sulfone)s effectively control film order.
- The 'homeo-planar smectic' phase represents a unique self-assembled structure with potential applications.
- The study provides insights into structure-property relationships in liquid crystalline polymers.