Polystyrene-block-polyacrylic acid is a diblock copolymer used for making polymeric micelles/ vesicles (polymersomes) and other encapsulation applications, . This PS-block-PAA copolymer is 10 wt. % PAA; and should form micelles in water in the 100~200 nm range. The polystyrene degree of polymerization (DP) is 275 and the polyacrylic acid DP is 30.