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A versatile new route to zwitterionic diblock copolymers that avoids protecting group chemistry is reported. Various tertiary amine methacrylates are block copolymerized with 2-hydroxyethyl methacrylate to produce hydroxy-functional diblock precursors via sequential monomer addition. These low-polydispersity precursors are then treated with succinic anhydride under mild conditions to produce a range of new near-monodisperse zwitterionic diblock copolymers in which both blocks are weak polyelectrolytes. Thus, the final copolymers exhibit complex aqueous solution behavior (isoelectric points, schizophrenic micellization behavior, etc.) depending on the solution pH.

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A new convenient route to well-defined, low-polydispersity polyacids is reported that does not require protecting group chemistry. First, near-monodisperse hydroxylated polymers are synthesized via ATRP of either 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, or glycerol monomethacrylate and then esterified using excess acid anhydride under mild conditions. For example, using a succinic anhydride/hydroxy group molar ratio of two in pyridine, essentially complete esterification of the hydroxy groups in poly(2-hydroxyethyl methacrylate) occurred within 48 h at 20 °C. Moreover, varying this molar ratio allows the final degree of esterification to be easily controlled. THF was examined as an alternative solvent, but a tertiary amine catalyst was required to achieve high degrees of esterification under these conditions. According to 1H NMR studies, the succinate ester bonds were susceptible to hydrolysis at or above pH 12 but were relatively stable at pH 2. Finally, a new poly(ethylene oxide)-based diblock copolymer was synthesized that dissolves molecularly at neutral pH but undergoes micellar self-assembly at low pH.