Triblock And Three-arm Poly(Ethylene Glycol)-Poly(ε-caprolactone) Copolymers: Aggregation Behavior In Water And As The Drug Carrier

Amphiphilic block copolymers can self-assemble into nano-sized aggregates in the presence of a selective solvent for one of the blocks and aggregates have the structures of hydrophobic core and hydrophilic shell. So it has a wide application in the drug delivery field. In this article, we aimed at triblock and three-arm poly (ethylene glycol)-poly (ε-caprolactone) copolymers, investigated the aggregation behavior of copolymers and morphologies of copolymer aggregates. Moreover, the three-arm copolymer used as the drug carrier was also studied.Dye solubilization method was used to determine the critical micelle concentration (CMC) values of triblock and three-arm copolymers. The experimental results showed that the CMC value decreased with increasing the PCL block length and the CMC values of three-arm copolymers were lower than those of the triblock copolymers. The distribution curves of the micelle diameters were unimodal by using direct dissolving method and precipitation/solvent evaporation method. In addition, the hydrodynamic diameters of these two kinds of copolymer micelles were 15-85 nm and had good thermal stability by using dynamic light scattering (DLS) method. PEG-PCL copolymer aqueous systems with high concentrations had temperature-responsive reversible phase transitions and the phase transition temperatures were influenced by the architecture and composition of the copolymers.Lyophilization was used to made copolymer samples and the atomic force microscopy (AFM) results showed that triblock copolymer self-assembled into spherical micelles in water; while the copolymer gel displayed a pattern of some...