Since the diblock copolymer was pH-sensitive, titration was conducted to find out the effective pKa . Firstly, around 5ml of 1wt% solution was made. The pH meter (Hanna HI98103 pH checker) was calibrated before use. The polymer solution was adjusted to pH 2 by adding hydrochloric acid (1 M). 20 μL of Sodium hydroxide solution (0.25M) was repeatedly added to the polymer solution, with the pH recorded after each addition, continued until the solution reached pH 12. The pKa was then determined by the titration curve (that can be found in Fig ) and it was taken as the pH were 50% of the amino groups are protonated.