Co-micellization behavior of triblock copolymers in the presence of hydrophobic drug molecules: A simulation study

Dissipative particle dynamics simulation of bead-spring chains is applied to study co-micellization, micellar and drug loading properties of binary triblock copolymer systems to seek a better understanding on selection and utilization of polymer mixtures to improve the drug encapsulation efficiency and loading capacity. Co-micellization is found to still occur in the presence of drug; pure and mixed micelles coexist with some devoid of any drug due to their significantly lower aggregation numbers. The drug encapsulation enlarges the micelle cores, and may induce a morphology transition from spherical to ellipsoidal or rod-like micelles. For the binary mixture of polymer species with a considerable difference in chain length, the majority of the shorter chains are located near the periphery of the hydrophobic core, because they prefer the loop conformation so as to join the micelles in the co-micellization process. Increasing the drug concentration causes more chains to become looped to facilitate the formation of larger micelles for drug accommodation.