Maleimide end-functionalized poly(2-oxazoline)s by the functional initiator route: synthesis and (bio)conjugation.

The synthesis of poly(2-ethyl-2-oxazoline)s with a maleimide group at the α chain end was carried out from new sulfonate ester initiators bearing a furan-protected maleimide group. The conditions of the polymerization were optimized for 50 °C using conventional heating (in contrast to microwave irradiation) to counteract the thermal lability of the cycloadduct introduced to protect the maleimide double bond. At this temperature, a tosylate variant was found to be unable to initiate the polymerization after several days.