Poly(norbornenyl azlactone) as a versatile platform for sequential double click postpolymerization modification
Résumé
Ring-opening metathesis polymerization (ROMP) of a heterofunctional azlactone-based monomer, namely norbornenyl azlactone (NBAzl), is reported for the first time using third generation ruthenium-based catalyst (G3′). It is demonstrated that ROMP of the mixture of stereoisomers of NBAzl obtained by Diels-Alder reaction between 2-vinyl-4,4-dimethyl-5-oxazolone (vinyl azlactone, VDM) and cyclopentadiene leads to well-defined polymers (Mn , SEC up to 52 500 g mol −1 , Ð < 1.37). The resulting polymers easily undergo click post-polymerization modification by aminolysis of the azlactone groups using amine nucleophiles. By using azido oligoethylene glycol amine, ROMP polymers having azido side-chains capable of alkyne azide click modification are prepared, that are not attainable by direct ROMP of azido-functionalized monomers. The successful clicking to the so-obtained azido-functional ROMP polymer was demonstrated by copper-catalyzed alkyne − azide cy-cloaddition (CuAAC) with alkyne-functionalized fluorescein. The reported versatile methodology produces with complete atom economy a platform for new functional polymer libraries, including polymer materials with potential medical and biological applications.
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