Anionic Synthesis of Narrow Molecular Weight Distribution Water-Soluble Poly(N,N-dimethylacrylamide) and Poly(N-acryloyl-N ‘-methylpiperazine)

Water-soluble poly( N, N -dimethylacrylamide) (PDMA) and poly( N -acryloyl- N ‘-methylpiperazine (PAMP) were prepared in tetrahydrofuran at −78 °C by anionic polymerization in the presence of monofunctional initiators such as (triphenylmethyl)lithium, or -cesium or the difunctional initiators (1,1,4,4-tetraphenylbutyl)lithium, -potassium, or -cesium or cesium naphthalenide. Polymerizations initiated especially in the presence of cesium as counterion proceeded in a homogeneous manner and gave polymers having controlled molecular weights and narrow molecular weight distributions in quantitative yields. However, the polymerization results in polymers with a lower molecular weight and a broad molecular weight distribution at higher reaction temperatures. Size exclusion chromatography, 1 H NMR spectroscopy, and intrinsic viscosity measurements support the clean anionic polymerization of DMA with few side reactions at −78 °C. Attempted anionic polymerizations of methacrylamide monomers such as N, N -dimethylmethacrylamide and N -methacryloyl- N ‘-methylpiperazine are described as well. NMR spectroscopy, differential scanning calorimetry, and solubilities of the resulting polymers revealed the influence of the initiator counterions on the polymer tacticity.