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Surface characterization of functionalized latexes with different surface functionalities using rheometry and dynamic
Jan S Vesaratchanon1, Koichi Takamura, Norbert Willenbacher
1Institute of Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology, Gotthard-Franz-Str. 3, 76131 Karlsruhe, Germany.
Journal of Colloid and Interface Science
|March 9, 2010
Summary
This study investigates "hairy" surface layers on latexes using various copolymers. Acrylic acid (AA) latexes showed the most extended, pH-sensitive layers, while acrylamide (AM) latexes exhibited reversible flocculation.
Area of Science:
- Colloid and Polymer Science
- Materials Science
- Surface Chemistry
Background:
- Sterically stabilizing "hairy" surface layers are crucial for latex stability.
- Understanding these layers informs particle interactions and processing behaviors.
Purpose of the Study:
- To investigate the formation and characteristics of "hairy" surface layers on different latex types.
- To analyze the influence of copolymer composition (acrylic acid, methacrylic acid, itaconic acid, acrylamide) and environmental conditions (pH, ionic strength, temperature) on layer formation.
Main Methods:
- Dynamic light scattering (DLS) for particle size analysis.
- Steady shear and high-frequency rheology for characterizing surface layers and colloidal interactions.
- Investigation across varying pH, ionic strength, and temperature conditions.
Main Results:
- Acrylic acid (AA) copolymerized latexes exhibited the most extended hairy layers, highly sensitive to pH and ionic strength.
- Methacrylic acid (MAA) resulted in thinner layers due to increased hydrophobicity.
- Itaconic acid (IA) produced ~1 nm layers, while acrylamide (AM) showed thin layers and weak, reversible flocculation.
- No significant impact of particle core composition or temperature on hairy layer formation was observed.
Conclusions:
- High-frequency rheology is a valuable tool for characterizing carboxylated latex surface layers, providing insights into effective volume fraction and colloidal interactions.
- The study highlights the distinct behaviors of different copolymers in forming stabilizing layers and their response to environmental factors.
- Findings are relevant for optimizing latex processing and manufacturing at high particle concentrations.
