Polymeric hydrogels loaded with hydrophobic chelating agents for solid phase extraction and sensing of ions

C.A BARBERO; M.V MARTINEZ; A B. MONCADA; C R. RIVAROLA; M.C MIRAS

Simposio; Fourth International Symposium Frontiers in Polymer Science; 2015

Polymeric hydrogels show large positive partition coefficients for organic molecules and metal complexes. This behaviour is likely to be related with hydrophobic interactions between the polymer chains of the hydrogel and the retained molecules.- Since dry hydrogels swell significantly (up to 200 times) in water, the exchange of molecules present in the aqueous solution could be driven by the swelling process. It has been shown that hydrogels containing chelating groups retain specific metal ions. In the present communication we investigate the loading of different chelating agents (phenanthroline, bathophenantroline, cuproine) into polyacrylamide based hydrogels. The chelating agent is loaded by swelling the hydrogel in solutions of the molecules, either made with water or nonaqueous solvents able to swell the hydrogels. The modified hydrogels show increased retention of specific ions (Fe+2, Cu+). By copolymerization of neutral acrylamides with charged groups (e.g. 2-Acrylamido-2-methylpropane sulfonic acid), the partition coefficient of cations increases due to columbic interactions. The materials are used to extract ions from aqueous solutions for water purification, Additionally, the preconcentration of a redox active complex increases the electrochemical signal inside the hydrogel allowing to build an amperometric sensor of the metal ion. On the same way, those chelators giving coloured complexes are used to build colorimetric sensors of ions. The hydrogels can be made as compact or macroporous solids, thin films or nanoparticles, which can be easily loaded with chelators. Therefore, the shape and composition of the material can be tuned to the specific application.