Synthesis and characterization of amphiphilic triblock copolymers and their self-assembly in aqueous solution

Polystyrene homopolymers synthesized via Reversible Addition-Fragmentation Chain Transfer polymerization were used as macro-chain-transfer agents to synthesize amphiphilic triblock copolymers with two hydrophobic blocks of PS and one hydrophilic block of PDMAE-MA. All Macro-CTA were characterized by GPC and NMR, the molecular weight of the Macro-CTA were 2100 g/mol, 3500 g/mol, 5000 g/mol, respectively, and all the Polydistribution Index were about 1.03. The structure of triblocks copolymers were confirmed by NMR. The shape of the micelles were studied by TEM. It is found that the shape of the micelles assembled in aqueous solution is sphere, and a layer PDMAEMA is confirmed by EDS in the surface of dried micelles, the size of the micelles is increased with the length of macromolecular, especially with length of the hydrophobic blocks. The thermo-and pH-sensitivity of the micelles were also investigated.