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Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by π-π Stacking Interactions
Published on: October 10, 2016
Structure formation of hydrophobically end-capped poly(ethylene oxide) in the solid state
Young-Wook Choi1, Jaehyun Park, Youngmi Park
1Department of Chemistry, Hanyang University, Seoul 133-791, Korea.
The Journal of Physical Chemistry. B
|October 26, 2007
Summary
Hydrophobically end-capped poly(ethylene oxide) undergoes conformational transitions from planar zigzag to helical structures as molecular weight increases. Hydrogen bonds break with temperature, influencing alpha-helical and beta-sheet conformations in different solvents.
Area of Science:
- Polymer Science
- Materials Science
- Physical Chemistry
Background:
- Hydrophobically end-capped poly(ethylene oxide) (HP-PEO-HP) exhibits complex conformational behavior.
- Understanding these transitions is crucial for designing advanced polymer materials.
Purpose of the Study:
- To investigate the conformational transitions of HP-PEO-HP with varying poly(ethylene oxide) (PEO) molecular weights.
- To elucidate the role of molecular weight and solvent quality on polymer conformation.
Main Methods:
- X-ray Diffraction (XRD)
- Differential Scanning Calorimetry (DSC)
- Fourier Transform Infrared Spectroscopy (FTIR)
Main Results:
- Conformational transitions from planar zigzag to 7/2 helical structures observed with increasing PEO molecular weight.
- HP-PEO-HP 1(18) showed alpha-helical structure in poor solvents and coexisting alpha and beta conformations in good solvents.
- Hydrogen bonds in alpha-helical structures broke at higher temperatures, favoring beta-sheet formation.
- HP-PEO-HP 2(18) and 4(18) exhibited spherulites, indicating a 7/2 zigzag helical conformation for the PEO molecule.
Conclusions:
- Molecular weight significantly influences HP-PEO-HP conformation, with higher PEO content favoring helical structures and spherulite formation.
- Solvent quality and temperature play critical roles in dictating the balance between alpha-helical and beta-sheet conformations.
- The study provides insights into the structure-property relationships of end-capped polymers.
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