My research is focused on microscopic, physical understanding of the origin of the unique material properties of polymers and complex fluids.
The hallmarks of these "soft" systems are:
- Interplay between thermal fluctuations and energetic tendency to order.
Exquisite sensitivity of structure to imposed fields,
particularly deformation and flow.
These features of soft systems afford unique opportunities for design and control of material properties,
but also pose substantial theoretical challenges. Material design in the huge parameter space of complex fluids cannot be achieved by a strictly empirical approach,
but requires a conceptual understanding as well, to successfully exploit the potential of these remarkable materials.
Current Research Areas
- Polymer dynamics (including stress relaxation in unlinked ring melts, simulating polymer motion in shear flow, polymer droplet spreading, and DNA elasticity).
- Glassy systems (including Tg shifts in polymer thin films, mobility in dense fluids, and force chains in jammed colloids).
- Ordering and crystallization (including rotator phases in alkanes, crystal nucleation in polyethylene, and flow-induced crystallization).
(including the topological origin of the tube, noninvasive methods to "see" the tube in simulations, and response of the tube to interfaces and strain).
Members of the Milner group employ a wide range of theoretical tools to solve their problems.
Broadly speaking, we use whatever it takes: equilibrium or nonequilibrium statistical mechanics at the micro- or mesoscale,
sometimes combined with Newtonian and non-Newtonian fluid mechanics at the meso- or macroscale.
Computational methods include:
- Molecular level simulation [for DNA elasticity, alkane rotator phases].
- Mesoscale MD and hybrid Monte Carlo simulations [for dense hard sphere fluids, entangled polymer melts].
- Lattice model simulations [for unlinked ring polymer dynamics, jammed solids, inhomogeneous glassy dynamics].
- Stochastic dynamics [for polymer chains in shear flow].
- Self-consistent mean field theory [for rotator twist solitons, gradient copolymer mesophases].
- Analytical theory [for thin-film polymer glasses].
- Physical scaling arguments [for flow-induced crystallization, gradient copolymer mesophases, tube diameter origins].