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Diffusion of entangled rod-coil block copolymers

Group members working on this project: Mitchell Wang
Collaborators: Alfredo Alexander-Katz

Despite increasing interest in the self-assembly of functional polymer systems, little research has focused on how the rigid, non-Gaussian molecular conformations of many functional polymers affect the dynamic properties that govern their diffusion, processing, and mechanics. Our group is currently studying the dynamics of entangled rod-coil block copolymers, an important category of molecules for self-assembled organic electronics and biomaterials and a starting point for understanding dynamics in non-Gaussian systems generally. Diffusion in the entangled regime is especially interesting both scientifically and technologically because the dynamics of rodlike polymers depart significantly from those of coil polymers, which dramatically affects the processing and self-assembly of materials in the melt. We have predicted theoretically that the different characteristic curvatures of the rod and coil blocks will cause the surrounding entanglements to respond to the blocks differently, resulting in fundamentally different diffusion behavior of rod-coils compared to rod and coil homopolymers. These results are being validated by molecular dynamics simulation and diffusion measurements by forced Rayleigh scattering.

Proteins have specific sequences, are perfectly monodisperse, and fold into complex shapes.

The different curvature of rod and coil blocks cause diffusion to occur by an activated process.


Proteins have specific sequences, are perfectly monodisperse, and fold into complex shapes.

Snapshot of molecular dynamics simulation of rod-coil block copolymers.