Step polymerization in various solvent conditions. A computer simulation approach using "Patchy Brownian Cluster Dynamics"
DIPC Seminars
- Speaker
-
Jean-Christophe Gimel (Micro and Nano-medicine laboratory, University Hospital in Angers)
- When
-
2015/03/25
13:00 - Place
- Donostia International Physics Center (DIPC). Paseo Manuel de Lardizabal, 4, Donostia
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" Step polymerization in various solvent conditions. A computer simulation
approach using "Patchy Brownian Cluster Dynamics" "
I will present a novel simulation technique derived from Brownian cluster
dynamics used so far to study the isotropic colloidal aggregation [1]. It now
implements irreversible patchy interactions between particles [2]. This
technique gives access to static properties, dynamics and kinetics of the
system, even far from the equilibrium. Particle thermal motions are modeled
using billions of independent small random translations and rotations,
constrained by the excluded volume and the connectivity. This algorithm,
applied to a single polymer chain leads to correct static and dynamic
properties, in the framework where hydrodynamic interactions are ignored.
By varying patch angles, various local chain flexibilities can be obtained. We
have used this new algorithm to model step-growth polymerization under various
solvent qualities. The polymerization reaction is modeled by an irreversible
aggregation between patches while an isotropic finite squarewell potential is
superimposed to mimic the solvent quality. In bad solvent conditions, a
competition between a phase separation (due to the isotropic interaction) and
polymerization (due to patches) occurs. Surprisingly, an arrested network with
a very peculiar structure appears. It is made of strands and nodes. Strands
gather few stretched chains that dip into entangled globular nodes. These
nodes act as reticulation points between the strands. The system is
kinetically driven and we observe a trapped arrested structure. That
demonstrates one of the strengths of this new simulation technique. It can
give valuable insights about mechanisms that could be involved in the
formation of stranded gels.
[1] Babu, S., Gimel, J.-C., and Nicolai, T., Phase separation and percolation
of reversibly aggregating spheres with a square-well attraction potential.
Journal of Chemical Physics, 2006. 125(19): p. 184512.
[2] Prabhu, A., Babu, S.B., Dolado, J.S., and Gimel, J.-C., Brownian cluster
dynamics with short range patchy interactions: Its application to polymers and
step-growth polymerization. Journal of Chemical Physics, 2014\. 141(2): p.
024904.
Host: Silvina Cerveny