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Published on: October 29, 2013
Strong intermolecular association between short poly(ethacrylic acid) chains in aqueous solutions
Sebastijan Peljhan1, Ema Zagar, Janez Cerkovnik
1Department of Chemistry and Biochemistry, University of Ljubljana, Askerceva 5, P.O. Box 537, SI-1001 Ljubljana, Slovenia.
The Journal of Physical Chemistry. B
|February 6, 2009
Summary
Short poly(alpha-ethylacrylic acid) chains strongly associate in water via hydrogen bonds and hydrophobic interactions. This behavior is observed across ionization degrees, influencing chain conformation and stability.
Area of Science:
- Polymer Chemistry
- Physical Chemistry
- Materials Science
Background:
- Poly(alpha-ethylacrylic acid) (PEA) behavior in aqueous solutions is crucial for understanding polyelectrolyte interactions.
- Previous studies have not fully elucidated the thermodynamic and structural aspects of PEA chain association.
Purpose of the Study:
- To conduct a comprehensive thermodynamic characterization of poly(alpha-ethylacrylic acid) chain transitions in water.
- To investigate the factors contributing to the association of PEA chains in aqueous media.
- To explore the conformational behavior of PEA chains using molecular modeling.
Main Methods:
- Conductometric, potentiometric, calorimetric, and fluorescence measurements were employed.
- Polymer characterization included molar mass, crystallinity, and tacticity analysis.
- Molecular modeling was performed on isotactic and syndiotactic PEA chains.
Main Results:
- Short PEA chains exhibit strong intermolecular association in aqueous solutions at 25°C.
- Association is driven by hydrogen bonding between un-ionized carboxyl groups and favorable hydrophobic interactions from ethyl side groups.
- Molecular modeling revealed "bent" or "curved" conformations for both isotactic and syndiotactic PEA isomers, confirming intermolecular hydrogen bonds.
Conclusions:
- Intermolecular association is a significant factor in the behavior of PEA in water, persisting across various ionization degrees.
- Hydrophobic interactions and hydrogen bonding play key roles in stabilizing associated PEA chains.
- The stereochemistry (tacticity) influences chain conformation and intermolecular interactions in PEA solutions.
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