pH-Tunable rheological properties of a telechelic cationic polyelectrolyte reversible hydrogel.

Steady shear properties and linear and nonlinear viscoelastic behaviors of a poly(methyl methacrylate)-poly(dimethyl amino ethyl methacrylate)-poly(methyl methacrylate) polymer, (PMMA-PDMAEMA-PMMA), telechelic polymers in salt-free aqueous solution have been investigated as a function of concentration and pH. Above a critical concentration, a transient physical network is formed through an association mechanism between hydrophobic end groups, leading to a gel-like behavior. The gel-like polymer solutions were shown to exhibit a peculiar flow behavior, associated with time fluctuation of the transient first normal stress difference, attributed to orientation effects of the stiff charged polymer chains.