Effect of Tail Architecture on Self-Assembly of Amphiphiles for Polymeric Micelles
LS Cheng and DP Cao, LANGMUIR, 25, 2749-2756 (2009).
Brownian dynamics simulations were carried out to explore the self- assembly of amphiphilic copolymers composed of a linear hydrophilic head and a hydrophobic tail with different architectures. In order to investigate the effect of architecture of hydrophobic tail on self- assembling behavior, these architectures of linear, branched, starlike, and dendritic tails were selected for comparison, and the branching parameter of the tail was employed to characterize the tail architectures, The critical micelle concentration (cmc), dynamics of aggregation, aggregate distribution, gyration radius distribution, density profiles of micelle, shape anisotropy, and thermal stability were examined for the four typical types of copolymers. The calculated results reveal that the self-assembly of linear tail copolymer has the lowest cmc, and the consequently formed polymeric micelles have narrow dispersion and greater aggregate size, and the micelle is closer to spherical shape. It was found that the cmc is inversely proportional to the branching parameter. Linear tail aggregates in solution to form polymeric micelles with higher physical stability, compared to other architectures of tail. The size of polymeric micelle increases with the increase of the branching parameter of die tail, and it exhibits an exponential relationship with the branching parameter. In addition, the micelles formed from copolymers with a high branching parameter of the tail were found to have higher thermal stability. This work provides useful information on designing self-assembling systems for preparing polymeric micelles applied to drug delivery.
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