The initial concentration of aPMA and iPMA for calorimetric measurements was set to cp = 0.012 mol L−1 or cm = 1 g L−1 (at αN = 0), and the ionic strength was I = 0.01 M for all metal chlorides, first for the better comparison of results with previous measurements20,32 and second to avoid precipitation of the polymers from solution at high αN.