Investigations of the dissociation behavior and interfacial adsorption characteristics of polyelectrolytes from poly(acrylamido‐2‐methyl‐1‐propane sulfonic acid) with an octadecyl side chain

Water‐soluble polymeric amphiphiles derived from acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) and octadecyl monomers in which the linker groups vary among acryloyl [octadecyl methacrylate (ODMAc)], maleate [octadecyl maleate ester (ODME)], and maleamic acid [octadecyl maleamic acid (ODMA)] have been synthesized. The dissociation behavior in water from potentiometric titration suggests that these polymers show resistance to neutralization. This might arise from coil structures, which effect the destabilization of sulfonate ions because of a proximity effect. The effect of the ? COOH group in modifying the dissociation behavior in the copolymers AMPS–ODME and AMPS–ODMA is indicated. The ratio of the intensities of the third vibronic peak (I₃) to the first vibronic peak (I₁) of the fluoroprobe pyrene in the presence of polymer solutions shows negligible changes as a function of pH, and this suggests the retention of micropolarity. The high I₃/I₁ value observed in the presence of the ODMAc polymer suggests intermolecular association. The reduction in the reduced viscosity with the concentration of the polymers suggests the polyelectrolyte behavior of all the copolymers. The progressive decrease in the reduced viscosity from 120 to 95 mL/g when the degree of ionization increases from 0.5 to 1 for the ODME polymer suggests changes in the solution structure. AMPS–ODMA and AMPS–ODME polymers exhibit significant adsorption at the interface and exhibit equilibrium surface tensions of 58.8 and 56.3 mN/m, respectively. The lower surface activity and higher reduced viscosity of ODMAc polymer solutions further support the formation of intermolecular associated or network structures. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 314–324, 2006