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'-methyl-piperazine (PAMP) were prepared in tetrahydrofuran at -78 de grees C by anionic polymerization in the presence of monofunctional in itiators such as (triphenylmethyl)lithium, or -cesium or the difunctio nal initiators (1,1,4,4-tetraphenylbutyl)lithium, -potassium, or -cesi um or cesium naphthalenide. Polymerizations initiated especially in th e presence of cesium as counterion proceeded in a homogeneous manner a nd gave polymers having controlled molecular weights and narrow molecu lar weight distributions in quantitative yields. However, the polymeri zation results in polymers with a lower molecular weight and a broad m olecular weight distribution at higher reaction temperatures. Size exc lusion chromatography, H-1 NMR spectroscopy, and intrinsic viscosity m easurements support the clean anionic polymerization of DMA with few s ide reactions at -78 degrees C. Attempted anionic polymerizations of m ethacrylamide monomers such as N,N-dimethylmethacrylamide and N-methac ryloyl-N'-methylpiperazine are described as well. NMR spectroscopy, di fferential scanning calorimetry, and solubilities of the resulting pol ymers revealed the influence of the initiator counterions on the polym er tacticity.