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Fabrication of Large-area Free-standing Ultrathin Polymer Films
Published on: June 3, 2015
Silica-surfactant-polyelectrolyte film formation: evolution in the subphase
Bin Yang1, Robben Jaber, Karen J Edler
1Department of Chemistry, University of Bath, Claverton Down, Bath, Avon, UK BA2 7AY.
Langmuir : the ACS Journal of Surfaces and Colloids
|May 11, 2012
Summary
Robust mesostructured films form from solutions containing cetyltrimethylammonium bromide (CTAB) and polyethylenimine (PEI). Silica addition rapidly forms mesophase particles, which then order into a 2D hexagonal structure, influencing film formation.
Area of Science:
- Materials Science
- Nanotechnology
- Physical Chemistry
Background:
- Mesostructured films are known to grow at the surface of alkaline solutions containing CTAB, PEI, and silica precursors.
- Understanding the formation mechanism is crucial for controlling film properties.
Purpose of the Study:
- To investigate the structural evolution of micellar solutions during the formation of mesostructured films.
- To quantify the size and shape of micelles in CTAB-PEI solutions.
- To elucidate the role of silica addition in particle and film formation.
Main Methods:
- Time-resolved small-angle X-ray scattering (SAXS) was used to study micellar solutions.
- Simple models were employed to quantify micelle size and shape.
- Previous neutron reflectivity data on films was utilized.
Main Results:
- No mesostructured particles were observed in CTAB-PEI solutions before silica addition.
- Silicate hydrolysis and condensation rapidly formed mesophase particles after silica addition.
- These particles rearranged into a 2D hexagonal ordered structure.
- A formation mechanism for CTAB-PEI-silica films at the air/water interface was developed.
Conclusions:
- Mesostructure evolution in the film mirrors that in solution particles.
- The liquid crystalline phase at the interface is not directly formed by the sub-interfacial particles.
- The study provides insights into the templating mechanism for mesostructured silica films.
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