Dried under vacuum at 70 °C overnight, PEG 6000 (20.0 g, 3.3 mmol) was dissolved in 60 mL anhydrous DCM in a round bottom flask, followed by the addition of Et3N (2.4 mL, 16.7 mmol) and DMAP (0.4 g, 3.3 mmol). The solution was then purged with nitrogen for 15 min. Next, succinic anhydride (1.69 g, 16.7 mmol) was added in portions and the reaction was left for 24 h. The mixture was washed with 1M HCl solution and water, and dried over anhydrous MgSO4. The solution was then concentrated and precipitated in diethyl ether twice. The obtained powder was then dried under vacuum overnight to give 15.6 g of the product. The degree of functionalization was determined to be 95% by 1 H NMR spectroscopy.