Macromolecular dynamics of sulfonated poly(styrene- b-ethylene- ran-butylene- b-styrene) block copolymers by broadband dielectric spectroscopy

• Published in: European polymer journal Vol. 47; no. 10; pp. 1936 - 1948
• Main Authors: Chen, Hongying, Hassan, Mohammad K., Peddini, Sateesh K., Mauritz, Kenneth A.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2011; Elsevier
• Subjects: Applied sciences; Blocking; Conductivity; Dielectric constant; Dielectric spectroscopy; Electrical, magnetic and optical properties; Exact sciences and technology; Glass transition; Mathematical analysis; Organic polymers; Permittivity; Phases; Physicochemistry of polymers; Polystyrene resins; Properties and characterization; Relaxations; SEBS block copolymers; Spectra; Sulfonation; SEBS block copolymers; Conductivity; Sulfonation; Dielectric spectroscopy; Relaxations; Terpolymer; Electrical properties; Ionic conductivity; Butadiene derivative copolymer; Experimental study; Segmental movement; Molecular relaxation; Dielectric relaxation; Saturated copolymer; Triblock copolymer; Styrenesulfonate copolymer; Styrene copolymer
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2011.07.005

ε″- f- T response surface for 11.7% sulfonated SEBS. [Display omitted] ► Chain dynamics of sulfonated SEBS were investigated by dielectric spectroscopy. ► Kramers–Krönig transformation was used to calculate conductivity-free spectra. ► S block relaxation time correlated with conductivity via fractional DSE equation. Macromolecular dynamics of sulfonated poly(styrene- b-ethylene- ran-butylene- b-styrene) (sSEBS) triblock copolymers were investigated using broadband dielectric spectroscopy (BDS). Two main relaxations corresponding to the glass transitions in the EB and S block phases were identified and their temperature dependences were VFT-like. T g for the S block phase shifted to higher temperature due to restrictions on chain mobility caused by hydrogen bonded SO 3H groups. While the EB block phase T g appeared to remain constant with degree of sulfonation in DMA experiments, it shifted somewhat upward in BDS spectra. A low temperature relaxation beneath the glass transition of the EB block phase was attributed to short range chain motions. The Kramers–Krönig integral transformation was used to calculate conductivity-free loss permittivity spectra from real permittivity spectra to enhance true relaxation peaks. A loss permittivity peak tentatively assigned to relaxation of internal S-EB interfacial polarization was seen at temperatures above the S block phase glass transition, and the temperature dependence of this relaxation was VFT-like. The fragilities of the EB and S block domains in sulfonated SEBS decreased after sulfonation. The temperature dependence of the dc conduction contribution to sSEBS loss spectra also followed VFT-like behavior and S block segmental relaxation time correlated well with conductivity according to the fractional Debye–Stokes–Einstein equation.