CO2‐responsive swelling behavior and metal‐ion adsorption properties in novel histamine‐conjugated polyaspartamide hydrogel

Novel polyaspartamide copolymers containing histamine pendants (PHEA‐HIS) were prepared from polysuccinimide, which is the thermal polycondensation product of aspartic acid, via a successive ring‐opening reaction using histamine (HIS) and ethanolamine (EA). The prepared water‐soluble copolymer was then crosslinked by reacting it with hexamethylene diisocyanate in order to provide a hydrogel with both good gel strength and reversible CO₂ absorption characteristics. PHEA‐HIS gel is also pH‐sensitive and eligible to coordinate to metal ions such as Pb²⁺, Cu²⁺, and Ni²⁺ due to the imidazole units in its structure. The CO₂‐responsive swelling behavior, metal‐ion adsorption, and morphology of the crosslinked gels were investigated. The approach described here results is a promising hydrogel with potential for a variety of industrial and biomedical applications including CO₂ capture, CO₂‐responsive and switchable sensors, and smart drug delivery systems. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43305.