Well-defined novel, linear, biodegradable, amphiphilic thermo-responsive ABA-type\ntriblock copolymers, poly[2-(2-methoxyethoxy) ethyl methacrylate-co-oligo(ethylene glycol)\nmethacrylate]-b-poly(�µ-caprolactone)-b-poly[2-(2-methoxyethoxy) ethyl methacrylate-co-oligo\n(ethylene glycol) methacrylate] [P(MEO2MA-co-OEGMA)-b-PCL-b-P(MEO2MA-co-OEGMA)] (tBPs),\nwere synthesized via a combination of ring-opening polymerization (ROP) of �µ-caprolactone\n(�µCL) and reversible addition-fragmentation chain transfer polymerization (RAFT) of MEO2MA\nand OEGMA comonomers. The chemical structures and compositions of these copolymers were\ncharacterized using Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic\nresonance (1H NMR). The molecular weights of the copolymers were obtained using gel permeation\nchromatography (GPC) measurements. Thermo-responsive micelles were obtained by self-assembly\nof copolymers in aqueous medium. The temperature sensitivity and micelllization behavior of\namphiphilic triblock copolymers solutions were studied by transmittance, fluorescence probe, surface\ntension, dynamic light scattering (DLS) and transmission electron microscopy (TEM). A hydrophobic\ndrug, anethole, was encapsulated in micelles by using the dialysis method. The average particle\nsizes of drug-loaded micelles were determined by dynamic light scattering measurement. In vitro,\nthe sustained release of the anethole was performed in pH 7.4 phosphate-buffered saline (PBS) at\ndifferent temperatures. Results showed that the triblock copolymerâ��s micelles were quite effective in\nthe encapsulation and controlled release of anethole. The vial inversion test demonstrated that the\ntriblock copolymers could trigger the sol-gel transition which also depended on the temperature, and\nits sol-gel transition temperature gradually decreased with increasing concentration. The hydrogel\nsystem could also be used as a carrier of hydrophobic drugs in medicine.
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