Sulfonated poly(ether-block-ester) ionomers with anions in the polyester hard segments

A series of poly(ether–block–ester) ionomers with different content of sodium sulfonate groups in the hard segments, and the random copolyesters poly(butylene terephtalate)/butylene isophthalate (PBT/BI) and poly(butylene terephalate/butylene 5′-sulfoisophthalate sodium salt (PBT/SBI) have been synthesized and examined. The methods of dynamic mechanical thermal analysis and differential scanning calorimetry were used to determine the effect of ionic units on the physical properties of sulfonated poly(ether–block–ester) (SPEE) ionomers and PBT/BI, PBT/SBI copolymers. It was established that the melting temperature and crystallization temperature of the SPEE ionomers decreases with the increase of content sodium 5-sulfoisophthalate in the hard segments, and that the crystallinity gradually decreases with the increase of ionic units content. The effect of ionic units content in hard segments on glass transition temperature of both soft and hard phase, E′, E″ and tan δ were studied.