David C. Morse, Principal Investigator

Computational Polymer Physics

These researchers are interested in computational polymer physics, which focuses on elucidating molecular origins of both equilibrium and dynamics behavior of polymer fluids. The group investigated two areas: • Statistical dynamics and vascoelastic behavior of solutions of semi-flexible polymers, studied by Brownian dynamics simulation • Statistical thermodynamics of self-assembling structures of block copolymers, studied by a self consistent field theory In application of this research program, the group studied the linear viscoelasticity of dilute solutions of semiflexible polymers, by means of Brownian dynamics simulation and theoretically. The shear relaxation modulus G(t) for chains that are shorter than their persistence length exhibits three time regimes: at very early times, when longitudinal deformation is affine, G(t) and the tension both decay; over a broad intermediate regime, during which the chain length relaxes, G(t) decays as t-5/4; at long times, G(t) is similar to that of rigid rods. The researchers have completed initial tests of the first working version of a code for interacting polymers. These simulations use a model of semiflexible bead-rod chains with constrained rod lengths (like the single chain simulations), which interact with rod-rod (rather than two-body bead-bead) repulsive interactions in a period unit cell. The initial version uses a linked-cell list to identify near neighbors. The first version of the code simulates a solution of uncrossable but infinitely thin line-like polymers, using an algorithm based on a geometrical criterion that prevents chains from crossing.

Research Group

Kwanho Chang, Graduate Student Researcher
Laura MacManus, Graduate Student Researcher
Matteo Pasquali, Research Associate
Shriran Ramanathan, Graduate Student Researcher
Viswanathan Shankar, Research Associate
Douglas E. Smith, Undergraduate Student Researcher
Christopher Tyler, Graduate Student Researcher