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Nanoparticle size controls aggregation in lamellar nonionic surfactant mesophase
Edakkal Venugopal1, Vinod K Aswal, Guruswamy Kumaraswamy
1Complex Fluids and Polymer Engineering, Polymer Science & Engineering Division, CSIR-National Chemical Laboratory, Pune 411008, India.
Langmuir : the ACS Journal of Surfaces and Colloids
|July 13, 2013
Summary
Silica nanoparticle size dictates aggregation behavior in surfactant solutions. Larger nanoparticles (>15 nm) reversibly aggregate, while smaller ones (<11 nm) aggregate irreversibly due to surfactant bilayer wrapping.
Area of Science:
- Materials Science
- Colloid and Surface Chemistry
- Nanotechnology
Background:
- Surfactant-nanoparticle interactions are crucial for colloidal stability.
- Nonionic surfactants like C12E4 form complex phases with water.
- Understanding nanoparticle aggregation is key for material applications.
Purpose of the Study:
- To investigate the influence of silica nanoparticle size on aggregation in a C12E4/water lamellar phase.
- To elucidate the mechanism of size-dependent nanoparticle aggregation.
- To explore the role of surfactant bilayer wrapping in stabilizing nanoparticles.
Main Methods:
- Dispersion of silica nanoparticles (8-26 nm) in a 75:25 C12E4/water system.
- Observation of nanoparticle aggregation behavior at different temperatures.
- Small-angle neutron scattering (SANS) to analyze nanoparticle-surfactant interactions.
Main Results:
- Silica nanoparticles smaller than 11 nm aggregate irreversibly.
- Silica nanoparticles larger than 15 nm aggregate reversibly with temperature changes.
- Aggregation behavior is explained by size-dependent surfactant bilayer wrapping.
Conclusions:
- Nanoparticle size critically controls aggregation in C12E4/water systems.
- Larger nanoparticles are stabilized by adsorbed surfactant bilayers, preventing irreversible aggregation.
- Smaller nanoparticles, unable to form stable bilayers, aggregate irreversibly.
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