Giant vesicles comprised of mixed amphiphilic poly(methacrylic acid)-block-poly(methyl methacrylate-random-methacrylic acid) diblock copolymers

The morphological changes in giant vesicles were investigated using mixed amphiphilic diblock copolymers consisting of poly(methacrylic acid)-block-poly(methyl methacrylate-random-methacrylic acid), PMAA-b-P(MMA-r-MAA). The mixed copolymers had the identical length of the hydrophobic P(MMA-r-MAA) block and different lengths of the hydrophilic PMAA block; long-length PMAA (PMAA-L) was about three times longer than short-length PMAA (PMAA-S). Large contorted vesicles formed by the copolymer containing PMAA-S were transformed into various elliptical and spherical vesicles, followed by worm-like vesicles as the ratio of the PMAA-L-containing copolymer increased. It was found that the vesicular morphology of the mixed copolymers was determined by the average length of the PMAA blocks contained in the mixed copolymers based on the comparison with the spherical vesicles formed only by the copolymer containing the middle length of the PMAA block.