Crystal-amorphous polymer interface studied by neutron and x-ray scattering on labeled binary ultralong alkanes
X B Zeng1, G Ungar, S J Spells
1Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD, United Kingdom.
Physical Review Letters
|May 7, 2003
Summary
Ultralong alkanes form a stable semicrystalline phase where chains tilt within crystal layers. Amorphous end segments of shorter chains and longer chains protruding from crystals show gradual order loss.
Area of Science:
- Materials Science
- Polymer Science
- Solid-State Chemistry
Background:
- Binary ultralong alkanes exhibit a recently discovered stable semicrystalline phase.
- Understanding the molecular arrangement in these phases is crucial for materials design.
Purpose of the Study:
- To investigate the structural characteristics of the semicrystalline phase in binary ultralong alkanes.
- To elucidate the chain conformation and amorphous segment behavior within this phase.
Main Methods:
- Small-angle neutron scattering (SANS).
- Small-angle x-ray scattering (SAXS).
Main Results:
- Confirmation of tilted chain structures within the crystal layers.
- Identification of approximately seven amorphous end carbons in the shorter alkane.
- Observation of longer chains protruding from both ends of the crystal.
- Preferential localization of end groups from longer chains in the middle of the amorphous layer.
Conclusions:
- The study confirms chain tilting and quantifies amorphous end segments in ultralong alkanes.
- Protruding longer chains exhibit a gradual loss of orientational order in the amorphous regions.
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