Development of Tunable Materials From Well‐Defined Alendronic Acid Functionalized Polyacrylamide: An Opportunity for Actinide Decontamination

ABSTRACT Bisphosphonic acid groups are emerging as promising functionalities for actinide decontamination, due to their high density of chelating sites. However, the chemistry of bisphosphonate (in particular alendronate) materials remains complex and underexplored. Herein, the synthesis of novel valuable materials, namely poly( N ‐isopropylacrylamide)‐ b ‐poly(acryloylmorpholine‐ co ‐alendronate acrylamide) (PNIPAAm‐ b ‐P(NAM‐ co ‐AleAAm)) was reported. These copolymers were synthesized in three steps. First, poly( N ‐isopropylacrylamide)‐ b ‐poly(acryloylmorpholine‐ co ‐ N ‐acryloxysuccinimide) (PNIPAAm‐ b ‐P(NAM‐ co ‐NAS)) diblock copolymers were prepared by RAFT polymerization. Then, bisphosphonic acid groups were grafted onto the preformed copolymers by a post‐polymerization modification reaction. Original produced alendronate‐based functional copolymers were either water‐soluble or capable of forming hydrogels under suitable concentration and temperature conditions. Sorption properties of such materials for actinides were investigated. For such purpose, the binding affinities of these functionalized copolymers for actinide surrogates, Nd(III) and Ce(III), were evaluated by isothermal titration calorimetry (ITC). Experimental results demonstrated good complexation efficiency, which logically raised with increasing bisphosphonic acid content. These results highlight the potential of well‐defined, tunable hydrosoluble/hydrogel bisphosphonate‐based polymers as high potential candidates for actinide decorporation applications.