Morpholine-functionalized polycarbonate hydrogels for heavy metal ion sequestrationElectronic supplementary information (ESI) available: Additional data regarding ethyl 5-methyl-2-oxo-1,3-dioxane-5-carboxylate synthesis and copolymerization, cross-linker, MALDI-ToF MS and 2-(morpholin-4-yl)ethyl functionalized homopolymer and hydrogel DSC. See DOI: 10.1039/c2py20937c

A new six-membered carbonate functionalized with 2-(morpholin-4-yl)ethyl was synthesized and copolymerized with a poly(ethylene oxide)-based cross-linker in a controlled, organocatalyzed ring-opening polymerization process. Well-defined functionalized aliphatic polycarbonate-based hydrogels were obtained with gel fractions reaching 99%. Moreover, the gels that contained 2-(morpholin-4-yl)ethyl groups revealed stimuli-responsive properties towards pH. In the meantime, swelling properties of the hydrogels were found to be reproducible and good stability was observed in the pH range of 4-7.2, while a relatively rapid degradation occurred in more basic solution (pH = 10). ICP MS measurements of aqueous lead( ii ) nitrate solutions revealed that the functionalized material possessed properties to withdraw and retain lead ions from aqueous solution. Fully biodegradable 2-(morpholin-4-yl)ethyl-functionalized aliphatic polycarbonate-based hydrogels of low ecological impact as a pH-responsive material are developed with the ability to withdraw and retain heavy and toxic metal ions, such as lead cations, from aqueous media.