The clustering behavior of three well clustered acrylate ionomers, i.e. poly(ethyl acrylate -co-Na acrylate) (PEA), poly(styrene-co-Na acrylate) (PS), and poly(vinylcyclohexane-co-Na acrylate) (PVCH) ionomers, was compared. It was found that the cluster phase became dominant at ca. 5 mol% for die PEA and PS ionomers but at 9 mol% for the PVCH ionomer. In addition, the temperature differences between the: matrix and cluster T(g)s were 54, 55 and 49 degreesC fur the PEA, PS, and PVCH ionomers, respectively. The very similar values for the PEA and PS ionomers, in spite of their difference in matrix T(g)s themselves, led to a postulation that the PEA ionomers have bigger multiplets and longer persistence length than the PS ionomers.