Polymer Physics

Gelation and network formation in polymer-grafted nanoparticles

Some initial work in our group, and from other groups suggests that polymer-grafted nanoparticles can for networks and equilibrium gels under the right conditions.  This is remarkable, since while gels are useful most gels represent non-equilibrium states that age, and disintegrate with time.  The idea of forming equilibrium gels which are non-perishable, is therefore attractive.  In this study we determine the conditions for the formation of equilibrium gels by grafted nanoparticles.

A basic understanding of coding is required.

Polymer grafted nanoparticles as separation and fuel cell membranes

Polymer membranes are popular in separation and fuel cell applications.  Moreover, nanoparticle-filled polymer membranes can simultaneously improve properties such as permeability and selectivity.  The challenge lies in stabilizing these membranes against phase separation.  Recent progress in grafting polymer onto the surface of nanoparticles may mitigate some of these challenges.  This project uses statistical mechanics to study the efficacy of grafted nanoparticles as effective membrane materials.

Basic programming ability is needed. 

The phase behavior of connected hard and soft particles.

A surprising new development in materials science and chemical engineering is the finding that mixtures of hard (colloidal), and soft (polymeric, or micellar) particles can self organize on length scales much larger than the diameter of either species.  In this project we explore the behavior of connected hard- and soft particles.  An elementary knowledge of coding is sufficient.

The role of shape in the self-assembly of polymer-grafted nanoparticles.

Traditionally, self-assembled structures are formed using chemical differences within a species.  Examples of this are the formation of micelles by detergents, and the formation of the phospholipid bilayer of the cell membrane.  In these systems it is the tendency to the hydrophobic and hydrophilic part to avoid each other that result in the self-assembled state.  However, a recent study (http://pubs.rsc.org/en/content/articlehtml/2017/sm/c7sm00230k) has pointed out that it is possible to form self-assembled states

The role of impurities in the self-assembly of polymer-grafted nanoparticles.

Traditionally, self-assembled structures are formed using chemical differences within a species.  Examples of this are the formation of micelles by detergents, and the formation of the phospholipid bilayer of the cell membrane.  In these systems, it is the tendency to the hydrophobic and hydrophilic part to avoid each other that result in the  self-assembled state.  However, a recent study (http://pubs.rsc.org/en/content/articlehtml/2017/sm/c7sm00230k) has pointed out that it is possible to form self-assembled state

Polymer scission in turbulent flows

The addition of even a small amount of polymer to a turbulent flow dramatically reduces drag in turbulent flows. Known as the Toms effect, this phenomena is exploited to reduce the pumping costs associated with transporting oil in pipelines. The source of this effect is the elastic feedback from polymers which are stretched-out by the flow. So it would seem that more stretchable polymers should produce a stronger effect, except for the fact that highly stretched polymers can undergo scission, breaking up into smaller and more rigid fragments.