Linear aggregation and liquid-crystalline order: comparison of
Monte Carlo simulation and analytic theory
Prof. Matthew Glaser
Physics Department
University of Colorado at Boulder
Date: 03/07/2011
Abstract
Many soft matter and biomolecular systems are composed of monomers that reversibly
assemble into rod-like aggregates. The aggregates can then order into liquid crystal
phases if the density is high enough, and liquid crystal ordering promotes increased
aggregate growth. Systems that display coupled aggregation and liquid crystal ordering
include water-soluble dyes, wormlike micelles, DNA and RNA, peptides and proteins,
and patchy colloids. Such systems display pronounced (essentially exponential)
equilibrium polydispersity of semi-flexible aggregates and strong coupling between
aggregation and liquid crystal ordering, features that make the formulation of a
quantitative theory challenging. I’ll describe the ingredients that go into the relevant
theory, including density functional theory of liquid crystalline ordering and polymer
theory of aggregate conformational entropy. Theoretical predictions are compared with
results from Monte Carlo simulations of simplified models of reversible linear
aggregation. Our analytic theory shows improvement compared to previous theory in
quantitatively describing the isotropic-nematic phase transition for relatively stiff
aggregates, but requires a better treatment of more flexible aggregates.