Dynamic Mechanical Study of Sodium Sulfonated Random Ionomers Based on Hydrogenated Styrene−Butadiene Copolymer

Abstract

Sodium sulfonated poly(styrene-ethylene-butylene) random ionomers [P(SEB-co-SSNa)] were obtained by hydrogenation, sulfonation, and neutralization of styrene-butadiene copolymers containing 45 wt % styrene. The dynamic mechanical properties were measured as a function of temperature for ionomers of a wide range of ion contents. Most of the ionomers showed two glass transitions, as well as a well-developed ionic plateau region in the storage modulus between the two glass transitions. The loss tangent peak of the upper Tg appeared below the decomposition temperature of the polymer, which permitted its detailed analysis as a function of ion concentration. The results of this study are explained on the basis of a recent model of morphology of ionomers in the solid state (the EHM model) and compared with those of the styrene-sodium methacrylate copolymers [P(S-co-MANa)] and sodium sulfonated polystyrene [P(S-co-SSNa)]. Considerable similarities exist in the properties of the matrix phase in the P(SEB-co-SSNa) and P(S-co-MANa) ionomer systems, in spite of the differences in composition. The P(SEB-co-SSNa) and P(S-co-SSNa) ionomer systems show similarities in the properties of the cluster phases, which, however, differ from those in the P(S-co-MANa). A detailed analysis of the storage modulus and the loss tangent curves showed that the storage modulus in the ionic plateau region is controlled by a filler effect of the dispersed phase (cluster or matrix) when there is only one continuous phase in the system. The storage modulus changes according to the logarithmic mixing rule when both the matrix and cluster phases are cocontinuous. Also, percolation theory can be applied to the modulus values of the P(SEB-co-SSNa) ionomer system.

Morphology of Sulfonated Random Ionomers Based on Hydrogenated Styrene–Butadiene Copolymer Studied by SAXS

“…7 mol%; above 10 mol% of ions, the volume fraction of the cluster regions does not change significantly with ion content. 8 From this, along with morphological data above, it can be concluded that when clustering is well-developed, scattering centers are also fully developed, and thus Bragg distance does not change significantly with ion content. Similar observations have also been made in the poly(styrene-co-methacrylate) ionomer system.…”

“…8 The PSEB copolymer is composed of 73 mol% of ethylene, 8 mol% of butylene, and 19 mol% of styrene. The polymer was sulfonated using a modification of the sulfonation method of Thaler.…”

“…7 The dynamic mechanical properties of sulfonated poly(styrene-co-ethylene-co-butylene) (SPSEB) random ionomers have been investigated. 8 Thus, as a follow-up work, the present study explores the morphology of the SPSEB ionomers. The comparison of the results obtained in this study with those from the sulfonated polystyrene ionomers is also made.…”

Biodegradable Aliphatic Polyester Ionomers

“…[54] Nishida et al investigated the dynamic mechanical properties of randomly sodium sulfonated poly(styrene-ethylene-butylene) ionomers and the filler concept was used to explain the increase in the storage modulus in the ionic plateau region. [55] The tan d curves for PBSis showed two T g , Figure 3(b). The main peak was assigned as the T g of the matrix, while the shoulder at a higher temperature reflected the T g corresponding to the ion cluster region.…”

Dynamic Mechanical Studies of the Sulfonated Butyl Rubber Ionomers and Their Blends

“…Fitzgerald and Weiss [12] studied the effect of glycerol and dioctyl phthalate on the dynamic mechanical properties of sulfonated polystyrene using a dynamic mechanical analyzer and smallangle X-ray scattering. Nishida and Eisenberg [13] studied the dynamic mechanical properties of sulfonated ionomer of hydrogenated (styrene-butadiene) rubber neutralized with sodium ions and indicated that most of the ionomers showed two glass transitions, as well as a well-developed ionic plateau region in the storage modulus between the two glass transitions. Nishida and Eisenberg [13] studied the dynamic mechanical properties of sulfonated ionomer of hydrogenated (styrene-butadiene) rubber neutralized with sodium ions and indicated that most of the ionomers showed two glass transitions, as well as a well-developed ionic plateau region in the storage modulus between the two glass transitions.…”