Poly(lactic acid) (PLA) were grafted to both ends of Pluronic F127 (PEO-PPO-PEO) to
produce novel amphiphilic PLA-F127-PLA block copolymers. The aggregation behaviors of three different
modified polymers were examined by laser light scattering and transmission electron microscopic
techniques. The structure of aggregates produced from moderate to long PLA segments (PLAF127-29
(230 units of PLA) and PLAF127-48 (500 units of PLA) systems, respectively) was found to be normal
bi-layer vesicles. Polymer with the shortest PLA segment (PLAF127-23 (142 units of PLA)) produces
aggregates with complicated onion-like vesicles containing three layers. These vesicles possess microstructure
similar to many biological systems, and they exhibit desirable properties for potential
applications as drug delivery vehicles.