Synthesis and characterization of some water soluble polymers

Homopolymers and copolymers of acrylamide (AA) and acrylic acid (AAc) were synthesized by the free radical solution polymerization technique. Feed ratios of the monomers were 85 : 15 (w/w), 65 : 35 (w/w), and 50 : 50 (w/w) of acrylamide and acrylic acid, respectively, for synthesis of copolymers. All reactions were carried out in aqueous media, except for the synthesis of polyacrylic acid, where the medium was n-butanol. Hydrogen peroxide, potassium persulfate, and benzoyl peroxide were used as initiators. The copolymers were purified by removing homopolymers. The homopolymers and copolymers were characterized by infrared (IR), C-13-nuclear magnetic resonance (NMR), H-1-NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and viscosity measurements. The fusion temperature and the energy change for various phase transitions were obtained from DSC measurements. The activation energy values for various stages of decomposition were calculated from TGA. The activation parameters for the viscous flow (i.e., free energy, enthalpy, and entropy of activation) were evaluated from the viscosity measurements. Voluminosity and Simha shape factor were also calculated for different systems. Effects of various concentrations of electrolytes, NaNO3, and Al(NO3)(3) on viscosity behavior were studied. (C) 1997 John Wiley & Sons, Inc.