Current
Research...
- Nanoparticles
We perform colloidal synthesis and measurements of
CdS, CdS-ZnS core-shell nanoparticles for understanding mechanism of
particle formation and for making stable, size controlled (2-10 nm)
nanoparticle dispersions. These dispersions are subsequently tried for
thin film formation by electrophoresis for coating applications. We also
make iron-oxide nanoparticles for the possibility of using it as a
contrast agent in magnetic resonance imaging, related to medical
diagnosis. Control of mean particle size and size distribution is
crucial in all these applications.
To gain further insight in the control variables, in parallel, we have
developed population balance equation based mathematical models and
performed Monte Carlo simulation of nanoparticle formation in
self-assembled colloids - like microemulsions, di-block copolymers etc.
This is done in conjunction with our and others' experimental data to
come up with predictive calculations for both spherical nanoparticles
and anisotropic nanostructures, like nanorods.
- Mesoporous
materials
We carry out experiments in making mesoporous
materials (like MCM-41, SBA-15) of controlled pore-size (5-20 nm) for
understanding structure and related adsorption and diffusion issues in
these small pores as a function of pore diameter. We further utilize
such porous silica matrices for making silver nanoparticles for water
purification (killing bacteria) and filtration studies, or make pores
functionalized to make them hydrophobic for water-organic mixture
separation. Sometimes, the porous silica is impregnated with dyes to use
them for detection of pH sensitive aqueous and gaseous mixtures. We are
working on extending these studies to make chemical sensors.
- Nanocomposites
Polymers (like PEPEG, Polyester, PS etc.) have
been used to make composites with our own (synthesized) mesoporous
materials or commercially available nanotubes. We try to explain the
enhanced mechanical strength, Young's modulus and damping properties (in
structural vibration) of these composites from detailed microstructural
studies, supplementing it with empirical calculations.
- Smart and Switchable Surfaces
Mesoporous thin films at oil-water interface have
been made with differential wetting characteristics across two surfaces
of the film. Thus one surface can selectively manifest itself as a
superhydrophobic one, whereas the other is hydrophilic in nature. In
some cases, we change the subphase composition to switch the behaviour
from hydrophilic to hydrophobic and vice versa. We want to take this
work further towards developing smart membranes or surfaces.
- Aerosols
We sample both outdoor (ambient) and indoor
(smoke) aerosols for studying formation and dynamics of particulate
matter, suspended in air or gas. On the other hand knowledge of
particle/aerosol formation mechanism is combined with our MC simulation
background to explain formation of useful particulate additives (like
TiO2) and reinforcing materials by aerosol-based reactors.
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