Solution properties of hydrophobically modified polyelectrolytes synthesized via solution and micellar copolymerization

Hydrophobically modified polyelectrolytes (HMPEs) were synthesized using sodium 2-acrylamido-2-methyl-propanesulfonate and N-n-dodecylacrylamide as monomers with the same feeding ratio via micellar and solution copolymerization. The effects of hydrophobic association and electrostatic interaction on the solution properties of the HMPEs were studied. Compared with HMPE obtained via solution copolymerization (s-PAD), the hydrophobic interaction of HMPE obtained via micellar copolymerization (m-PAD) is more obvious due to the micro-blocky distribution of hydrophobic groups. The viscosity properties of m-PAD in deionized water or brine follow well the scaling theory of polyelectrolytes. However, for s-PAD, the concentration where zero-shear viscosity (eta(0)) and solvent viscosity (eta(s)) follow eta(0) approximate to 2 eta(s) is more likely to be critical entanglement concentration (c(e)) rather than critical overlap concentration (c*). It is suggested that modifying of the transition region from c* to c(e) is valid and reasonable for s-PAD. It is believed that the different solution properties of s-PAD and m-PAD should be attributed to the distributions of hydrophobic groups in the chains. (C) 2010 Society of Chemical Industry