The molecular weight of each block is shown in the parenthesis following the name of the block. PLA-PEG-PLA is an amphiphilic ABA triblock copolymer consisting of a hydrophilic block polyethylene glycol (PEG) or polyethylene oxide (PEO) and two hydrophobic block polylactide. The hydrophobic blocks terminate with a hydroxyl group. Biocompatible PEGylated copolymers with biodegradable polyester segments can be used to prepare core-shell micelles, nanoparticles and microspheres.
References: 1) Biodegradable long-circulating polymeric nanospheres. Science 1994;363:1600â€“3, Text.