Macromolecules, Vol.29, No.5, 1746-1752, 1996
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 degrees 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, H-1 NMR spectroscopy, and intrinsic viscosity measurements support the clean anionic polymerization of DMA with few side reactions at -78 degrees 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.
Keywords:BLOCK CO-POLYMERS;POLY(TERT-BUTYL ACRYLATE) DIBLOCK;DIPOLE-STABILIZED CARBANIONS;CAPPED POLY(ETHYLENE OXIDE);TRIBLOCK COPOLYMERS;ACRYLIC-MONOMERS;AQUEOUS-SOLUTION;POLYMERIZATION;MICELLIZATION;ASSOCIATION