Kinetics of Chain Exchange between Diblock Copolymer Micelles

A Prhashanna and SA Khan and SB Chen, MACROMOLECULAR THEORY AND SIMULATIONS, 25, 383-391 (2016).

DOI: 10.1002/mats.201600016

Dissipative particle dynamics simulation is employed to study the chain exchange kinetics between micelles of diblock copolymer in aqueous solution via in silico hybridization method. One focus is placed on the effect of chain fl exibility on the dynamic behavior by varying the spring constant in the bead- spring model. The length ratio of hydrophilic to hydrophobic block is also varied. It is found that chain expulsion/insertion is the dominant mechanism in the chain exchange process. The most interesting fi nding is the multimodal relaxation behavior for the chain exchange and expulsion when the spring constant is small or the length ratio of hydrophilic to hydrophobic block is large. This phenomenon is due to an increase in size polydispersity of micelles with rising population of small aggregates/micelles, for which the exchange kinetics is faster. Micelles with larger aggregation numbers (>10) are found to follow single exponential relaxation kinetics.

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