The properties of poly(styrene-co-citraconate) ionomers were investigated dynamic mechanically. It was found that the loss tangent peak for the matrix glass transition decreased with increasing content of ionic units, while the loss tangent peak for the cluster glass transition was barely detectable. However, the ionic modulus values of the citraconate ionomers as a function of the amount of ionic units were comparable to those of well-clustered methacrylate ionomers. Thus, it was postulated that the ionic modulus was affected by both clustering due to the overlapping of regions of restricted mobility and strong physical cross-links originated from the ionic association of ca. 4 ion pairs.