Highly distensible nanostructured elastic hydrogels from AB diblock and ABA triblock copolymer melt blends

Abstract

A new structural motif for the generation of highly distensible, highly elastic, nanostructured hydrogels is presented. Based on the swelling of vitrified melt-phase blends of sphere-forming polystyrene–poly(ethylene oxide) diblock and polystyrene–poly(ethylene oxide)–polystyrene triblock copolymers, the equilibrium swelling ratio (3.8–36.9 g H₂O per g polymer) and dynamic elastic modulus (G′ = 1700–160 000 Pa) of these novel hydrogel systems were found to be remarkably tunable through simple manipulation of temperature (10–50 °C) and triblock copolymer content (3.3–72.0 mol%). Mechanical properties were found to be almost exclusively a function of triblock copolymer content, independent of temperature induced changes in swelling ratio. The resulting hydrogels were highly elastic at all swelling ratios with G′/G″ ≈ 10² for the range of triblock copolymer concentrations examined. Hydrogel samples exhibited excellent preservation of dry polymer shape upon swelling, with complete recovery of both shape and mechanical performance following repeated compression–decompression cycles.