Preparation, characterization, and some properties of ionomers from a sulfonated styrene–butadiene–styrene triblock copolymer without gelation

Abstract

ABSTRACT:The conditions for the sulfonation of a highly unsaturated styrene-butadiene-styrene triblock copolymer (SBS) in cyclohexane containing a small amount of acetone with acetyl sulfate made by sulfuric acid and acetic anhydride without gelation were studied. After neutralization with metallic ions, the ionomers were characterized with IR spectrophotometry, dynamic mechanical analysis, and transmission electron microscopy. The melt flow, solution properties, and mechanical properties of the ionomers were studied. The results showed that gelation occurred during the sulfonation of SBS in cyclohexane at a 5-10% concentration without acetone, whereas in the presence of 5-10 vol % acetone, sulfonation proceeded smoothly without gelation. Transmission electron microphotographs of the lead ionomer indicated the presence of ionic domains. A dynamic mechanical spectrum showed the presence of three transition temperatures: Ϫ82.9, 68, and 96.5°C. The melt viscosity of the ionomer increased with the sulfonate content. The melt viscosity of the different ionomers neutralized with different cations seemed to decrease with decreasing ionic potential for both monovalent cations and divalent cations The solution viscosity of the sodium-sulfonated ionomer increased with increasing sulfonate content. The ionomer still behaved as a thermoplastic elastomer and showed better mechanical properties than the original SBS.

Synthesis of highly sulfonated polystyrene-based block copolymers soluble in tetrahydrofuran

“…A slight excess of acetic anhydride relative to sulfuric acid (Ac 2 O/H 2 SO 4 = 1.1-2.0) is usually used to scavenge a small amount of water present in H 2 SO 4 . On the other hand, a higher excess can lead to the side reaction, as reported in the literature [14]. The acetyl sulfate formation is an equilibrium reaction depending on temperature.…”

“…Thus, sulfonation of styrene homopolymer [3][4][5][6][7], styrene-ethene (propene, butene) [8][9][10][11][12][13], styrene-butadiene [14][15][16][17], and styrene-isobutylene [18][19][20] copolymers has been described and the resulting sulfonated (co)polymers have been intensively studied.…”

Novel Sulfonated Ethylene/1-Octene Copolymer Ionomer Nanocomposite: Synthesis and Properties

“…Along with the suitable conditions, the melt flow, solution viscosity and mechanical properties of the polar functionalized SBS were also investigated. Xie et al also reported the enhancement in mechanical properties of polar functionalized SBS compared to pristine polymer and illustrated the decreasing ionic potential of mono valent and divalent cations present in the corresponding salt of ionomer decrease the melt viscosities 12 .…”

“…Moreover several papers related to sulfonation of rubber like polymers have been published. For instance, Xie et al investigated several properties like melt flow, solution viscosity, and mechanical properties of polar functionalized styrene-butadiene-styrene (SBS) triblock copolymer which has significant applications like adhesives for polar substances and compatibilizers for blends of polar and non-polar polymers 10 .…”

“…Xie et al studied about the favorable conditions for carrying out the sulfonation in highly unsaturated macromolecule like SBS triblock copolymer without gelation as the polymers of high degree of unsaturation undergo gelation creating problems during sulfonation 12 . Along with the suitable conditions, the melt flow, solution viscosity and mechanical properties of the polar functionalized SBS were also investigated.…”