Self-assembled networks
Participating group members: Xinjiang Lü

Equilibrium polymers may, through intrinsic attractions or through other molecules, undergo reversible branching or crosslinking to form networks. The cytoskeleton, whose strong and and dynamic framework provides structure, strength, and mobility to eukaryotic cells, is an example of a self-assembled network.  To better understand this and other examples, we are running Monte Carlo simulations of the structures and phase transitions of this class of material.  The images show snapshots generated from simulations in which the crosslink angle was restricted to 90 ± 6 degrees (left) or to 31 ± degrees (right).  Crosslink sites are shown in blue; polymer chains are shown in red. For more information, see here.


Membrane vesicle formation
Participating group members:
David Zhao 

Vesicles, or closed shell-like structures, are commonly formed from lipid membranes.  They are useful for encapsulating drugs and other products, for targeted or time-released delivery.  We are using a simple mechanical representation of the membrane to calculate the free energy landscape of the formation of vesicles from membrane fragments.

  Simulation snapshot of a large irregular vesicle



Equilibrium polymers
Participating group members: LaKedra Pam, Xinjiang Lü

A range of systems, including proteins like f-actin and wormlike micelles, exhibit reversible 1-dimensional association into polymers or polymer-like structures.  We have performed Monte Carlo simulations using a simplified equilibrium polymer model in which the strength of the associations and the rigidity of the chains can be easily varied.  Using this model, we can make predictions about the conditions required for the nematic orientational ordering of the chains and about chain length distributions.

Simulation snapshot of an equilibrium polymer nematic phase, with short chains highlighted in red to emphasize their lower degree of ordering.

For more information, see here.


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