A. Betaine is grafted onto PED via an amide bond, yielding a polycation with a quaternary ammonium functional group. B. 1H NMR spectrum of B-PED; a (ethylene glycol), b (α proton on aspartate), c (trimethyl amine) (solvent peak: δ4.70). C. GPC of PED shows an MW of 38 kDa; B-PED is estimated to have an MW of ~46 kDa. D. FTIR spectrum reveals successful betaine conjugation onto PED; a,b: amide bond absorption; c,d: absorption peaks from betaine.