Living cationic polymerization of 2‐vinyloxyethyl phthalimide: Synthesis of poly(vinyl ether) with pendant primary amino functions

Cationic polymerization of 2‐vinyloxyethyl phthalimide (1) in CH2Cl2 at −15°C with hydrogen iodide/iodine (HI/I2) as initiator led to living polymers of a narrow molecular weight distribution (M̄w/M̄n = 1.1–1.25). The number‐average molecular weight of the polymers was in direct proportion to monomer conversion and could be controlled in the range of 1000–6000 by regulating the 1/HI feed ratio. However, when a fresh monomer was supplied to the completely polymerized reaction mixture, the molecular weight of the polymers was not directly proportional to monomer conversion. The polymerization of 1 by boron trifluoride etherate (BF3OEt2) in CH2Cl2 at −78°C gave polymers with relatively high molecular weight (M̄w > 20,000) and broad molecular weight distribution (M̄w/M̄n ∼ 2). The HI/I2‐initiated polymerization of 1 was an order of magnitude slower than that of ethyl vinyl ether, probably because of the electron‐withdrawing phthalimide pendant. Hydrazinolysis of the imide functions in poly(1) gave a water‐soluble poly(vinyl ether) (3) with aliphatic primary amino pendants.