Properties and influence of hydrophobically associating polyacrylamide modified with 2-phenoxylethylacrylate

The properties of hydrophobically associating copolymer P(acrylamide (AM)/2-phenoxylethylacrylate (POEA)), composed of acrylamide and a small amount of POEA (1.0 mol.%) as hydrophobe, were investigated in aqueous solution under various conditions. The results showed that the solution properties were strongly affected by the microstructure of copolymer. The copolymers (BP series) with hydrophobic microblocky structure exhibited large viscosity enhancement due to the intermolecular hydrophobic association, while that did not occur for the random copolymers (RP series). The hydrophobic association thickening behaviors were also remarkably dependent on the number and length of the hydrophobic block in polymer chain. Nonlinear viscosity relationship was found as increasing hydrophobe content and SMR (surfactant/hydrophobic monomer molar ratio), and a maximum appeared at the middle position as a result of the competitive effect between inter- and intra- molecular hydrophobic associations. Solution properties were further studied as a function of the polymer concentration, salinity, temperature and shear rate. The block copolymers show high salt tolerance and shear thinning as well as recovery after shear. © 2008 Higher Education Press.