The synthesis of the ABA triblock copolymer, comprising 2-methyl-2-oxazine (MeOzi) as block A and 2-pentyl-2-oxazoline (PentOx) as block B, was performed via living cationic ring opening polymerization (LCROP) and the product was characterised by H NMR spectroscopy and SEC (Figure ). During synthesis, a colour change of the reaction mixture from colourless to orange was observed, suggesting some undesired side reactions. Also, the required reaction time of the hydrophilic block was significantly longer than 2-methyl-2oxazoline (MeOx), due to the lower reactivity of MeOzi. Important to note, we used benzylbromide as an initiator, as the polymerization with the commonly used methyltriflate was not successful (no detailed analysis was conducted at this point). However, the change of the initiator coincided with a higher dispersity (Đ= 1.45) than typically obtained for the LCROP.