AbstractRandom copolymers of styrene and methacrylic acid were prepared in a wide composition range, and their conformational properties were investigated by potentiometric methods in different solvent media. A conformational transition occurs as a function of the degree of ionization (α). The Gibbs free energy change of the transition between uncharged conformers (ΔG0) was determined. The dependence of ΔG0on styrene content as well as on the composition of the solvent mixture and the temperature, shows that theunchargedpolyelectrolyte chains assume a compact conformation (globule) stabilized by hydrophobic interactions of maximum strength.Rough considerations on the electrostatic free energy of the macroion indicate that the dimensions of the compact form increase between α=0 and the transition point, so that the “globule” does not participate in the conformational change. It is suggested that this latter occurs in a one‐dimensional system, depending on the interaction of neighbori