Action of N-hydroxyphthalimide on chain stereoregularity in the radical polymerization of methyl methacrylate

N-Hydroxyphthalimide (NHPI) has a dual function in the radical polymerization of methyl methacrylate (MMA): this compound acts as an initiator and also provides for stereochemical control of the polymer chain. Lowering the polymerization temperature leads to increased syndiotactic specificity in the polymethyl methacrylate molecule. The action of NHPI as an initiator and stereoregulator is attributed to the capacity of this compound to form a hydrogen bond with the monomer molecule and growing macroradical.