Our work focuses on interactions within colloidal systems. Technically,
most of our research involves the applications of transport phenomena principles
to problems involving colloids and macromolecules. This activity includes
theoretical and experimental investigations of the electrokinetic and hydrodynamic
separation of colloidal dispersions using microcapillaries. We also collaborate
with other faculty from chemical engineering and other departments in the
NSF Polymer Interfaces Center at Lehigh in studying both the thermodynamics
and kinetics of the adsorption of polymers and their configuration on smooth
planar surfaces as well as on the surface of colloidal particles. Other
projects include rheological studies of aqueous colloidal dispersions and
solutions of associative polymers, studies of the stability of colloidal
dispersions, miniemulsion copolymerization, and interparticle transport
in miniemulsions.
Rheology
of Dispersions
Theory and experiments are being used to elucidate the rheological behavior
of solutions of water soluble associative polymers, colloidal dispersions,
micellar dispersions and their mixtures. Our work is primarily carried
out using model systems of industrial interest. The model associative polymers
used in our studies are block copolymers that are either hydroxyl (hydrophilic),
or alkyl (hydrophobic) terminated backbones of poly (oxyethylene) of molecular
weights ranging from 10000 to 100000. Efforts are aimed at developing structural
models which are of great importance in interrelating the microstructure
with their rheological behavior. |
Electrokinetic
and Hydrodynamic Fractionation of Colloidal Dispersions
Research in the area of size fractionation of charged Brownian-sized particles
by flow through packed beds and open capillary tubes is being directed
towards a fundamental understanding of the flow-separation mechanisms and
the axial dispersion phenomena. My interest is in developing models for
the movement of charged colloidal particles, both spherical and non spherical,
that include the forces of interaction between the particles and the surface
of the capillary. In particular, the presence of electrostatic (due to
the anionic surfactant present in the eluant) and steric (due to adsorbed
non-ionic polymeric surfactants) repulsive forces are being systematically
investigated. Current work involves studies of mixtures of anionic and
non-ionic surfactants in order to provide a steric repulsive potential
that will further decrease particle concentration near the surface of the
capillary. The motion of the colloidal particles is achieved through either
bulk fluid motion, electrokinetic forces, or external driving forces of
gravitational or electrical origin. The theme of this research is a fundamental
understanding of the role played by the physicochemical phenomena in the
area of hydrodynamic and electrokinetic behavior of colloids and its application
to fractionations. Of particular interest from a fundamental and practical
viewpoint is the analysis of the colloidal particles after their separation
in the flow field inside the capillary. |
Ph.D. Lehigh University, 1978 