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A Comparison between Hydrophobically End-Capped Poly(ethylene oxide) with Ether and Urethane Bonds
Alami1, Abrahmsén-Alami, Vasilescu
1Department of Physical Chemistry, Uppsala University, Uppsala, 751 21, Sweden
Journal of Colloid and Interface Science
|September 15, 1997
Summary
Hydrophobically modified ethylene oxide urethane (HEUR) associative polymers (AP) with ether versus urethane end-caps show distinct water association and clouding behaviors. Differences diminish at higher polymer concentrations, impacting solution dynamics.
Area of Science:
- Polymer Science
- Materials Science
- Physical Chemistry
Background:
- Associative polymers (AP) self-assemble in solution, forming networks critical for their properties.
- Hydrophobically modified ethylene oxide urethane (HEUR) polymers are a key class of APs with tunable characteristics.
- Subtle changes in polymer architecture, such as end-group linkage, can significantly alter solution behavior.
Purpose of the Study:
- To compare the solution behavior of two HEUR associative polymers differing only in the end-cap linkage (ether vs. urethane).
- To investigate how polymer architecture influences initial association, aggregation, and clouding in aqueous solutions.
- To determine the effect of polymer concentration on the observed differences in solution dynamics.
Main Methods:
- Synthesis and characterization of two HEUR polymers with dodecyl end-groups linked via ether (AP14) and urethane (AP14NCO) bonds.
- Fluorescence spectroscopy to probe polymer association.
- Dynamic light scattering (DLS) to measure aggregate size.
- NMR self-diffusion to study molecular mobility.
- Turbidimetry to determine clouding temperatures.
- Viscosity measurements to assess solution rheology.
Main Results:
- The urethane-linked polymer (AP14NCO) exhibited earlier aggregation and a higher clouding temperature compared to the ether-linked polymer (AP14).
- Initial association and aggregation dynamics were markedly different due to the subtle architectural variation.
- At polymer concentrations above 2-3 wt%, the distinct solution behaviors and transport dynamics between AP14 and AP14NCO became less pronounced.
Conclusions:
- The end-cap linkage in HEUR associative polymers significantly impacts their self-assembly, aggregation, and phase behavior in water.
- While initial solution properties are sensitive to subtle architectural differences, these effects become less dominant at higher polymer concentrations.
- Understanding these structure-property relationships is crucial for designing HEUR polymers for specific applications.