Interfacial rheology of an ultrathin nanocrystalline film formed at the liquid/liquid interface.
We report the interfacial properties of monolayers of Ag nanoparticles 10-50 nm in diameter formed at the toluene-water interface under steady as well as oscillatory shear. Strain amplitude sweep measurements carried out on the film reveal a shear thickening peak in the loss moduli (G") at large amplitudes followed by a power law decay of the storage (G') and loss moduli with exponents in the ratio 2:1. In the frequency sweep measurements at low frequencies, the storage modulus remains nearly independent of the angular frequency, whereas G" reveals a power law dependence with a negative slope, a behavior reminiscent of soft glassy systems. Under steady shear, a finite yield stress is observed in the limit of shear rate .gamma going to zero. However, for .gamma > 1 s-1, the shear stress increases gradually. In addition, a significant deviation from the Cox-Merz rule confirms that the monolayer of Ag nanoparticles at the toluene-water interface forms a soft two-dimensional colloidal glass.
Krishnaswamy
Rema
R
Department of Physics, Indian Institute of Science, Bangalore 560012, India.
Majumdar
Sayantan
S
Ganapathy
Rajesh
R
Agarwal
Ved Varun
VV
Sood
A K
AK
Rao
C N R
CN
D002627:Chemistry, Physical / Q000379:methods; D003102:Colloids / Q000737:chemistry; D003460:Crystallization; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D015233:Models, Statistical; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D009991:Oscillometry; D012212:Rheology / Q000379:methods*; D012834:Silver / Q000737:chemistry; D013997:Time Factors; D014050:Toluene / Q000737:chemistry; D014867:Water / Q000737:chemistry
D003102:Colloids; D014867:Water; D014050:Toluene; D012834:Silver