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The distinct character of surfactant gels: A smooth progression from micelles to fibrillar networks.
S. R. Raghavan
Langmuir, 25, 8382 (2009)
This Perspective argues that gel formation by surfactants is a process similar to micellization rather than crystallization; it is controlled by thermodynamics rather than kinetics.


Photogelling colloidal dispersions based on light-activated assembly of nanoparticles.
K. Sun , R. Kumar and S. R. Raghavan*
Journal of the American Chemical Society, 131, 7135 (2009)
A low-viscosity sol of clay nanoparticles is converted to a gel (infinite viscosity) by UV irradiation. The key is the use of a photoacid generator, due to which the pH is lowered upon irradiation. All components are commercially available.


pH-responsive Jello: Gelatin gels containing fatty acid vesicles.
M. B. Dowling, J. H. Lee and S. R. Raghavan*
Langmuir, 25, 8519 (2009)
We entrap vesicles of oleic acid in gelatin gels (Jello). When the gel is placed in a high pH bath, the vesicles inside the gel are disrupted into micelles. This can be used to tune the rate of release of a dye from the vesicle-loaded gel.


A simple method to improve the clarity and rheological properties of polymer/clay nanocomposites.
B. H. Cipriano, T. Kashiwagi, X. Zhang and S. R. Raghavan*
ACS Applied Materials & Interfaces, 1, 130 (2009)
Polymers are typically mixed with organoclays to make nanocomposites. We show that fractionating a commercial organoclay to remove large aggregates greatly improves the clarity and melt rheology of the nanocomposites.


Polymerizable vesicles based on a single-tailed fatty acid: A simple route to robust nano-containers.
J. H. Lee, D. Danino and S. R. Raghavan*
Langmuir, 25, 1566 (2009)
We show that polymerizable vesicles can be made using an inexpensive, commercially available fatty acid, UDA that has a terminal double bond. The polymerized vesicles can withstand the addition of detergents.


Persistence of birefringence in sheared wormlike micelles.
B. D. Frounfelker, G. C. Kalur, B. Cipriano, D. Danino and S. R. Raghavan*
Langmuir, 25, 167 (2009)
We describe and explain the unusual behavior of some wormlike micellar solutions whereby their flow-birefringence persists for hours and even days after shear is stopped. This behavior is shown by the movie here.


Photogelling fluids based on light-activated growth of zwitterionic wormlike micelles.
R. Kumar and S. R. Raghavan*
Soft Matter, 5, 797 (2009)
We describe a class of photogelling fluids based on a zwitterionic surfactant and an organic additive. The fluid undergoes a 10,000-fold increase in viscosity upon UV irradiation due to the light-induced growth of wormlike micelles.



 
© 2007 Srinivasa Raghavan |
 
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