ABC triblock copolymer hamburger-like micelles, segmented cylinders, and Janus particles

An ABC linear triblock copolymer with a carboxyl-containing terminal C block and a photocrosslinkable middle B block was synthesized and characterized. In a poor solvent for the B block and in the presence of a diamine, (−)-sparteine, which complexed with the C block and made it insoluble, the triblock copolymer self-assembled into hamburger-like micellar aggregates and segmented cylinders. In a “hamburger”, the “buns” were made of the B block, the filling was made of the complexed C block, and the soluble A chains stretched out from the bun surface into the solvent phase. The main body of the segmented cylinders was made of stacking alternating B and C stubs. The cylinders were dispersed in solvent by the A chains stretching out from the surfaces of the B stubs. After the photocrosslinking of the buns of the hamburgers and the removal of (−)-sparteine by dialysis, we were able to separate the buns of the hamburgers to yield presumably Janus particles.