Spin Capturing with "Clickable" Nitrones: Generation of Miktoarmed Star Polymers

Abstract

A novel nitrone (alpha-4-(3-(trimethylsilyl)prop-2-ynyloxy)-N-tert-butyl nitrone) with an alkyne "click" function is synthesized and employed in enhanced spin capturing polymerization (ESCP) as well as in radical coupling reactions between polymers preformed by atom transfer radical polymerization (ATRP) to generate midchain functionalized polymers. Both techniques allow for the facile introduction of chemical functionalities into a polymer midchain position and hence provide an attractive synthetic avenue for the construction of complex macromolecular architectures, Such a strategy is evidenced by the efficient use of polystyrene and poly(isobornyl acrylate) featuring an alkoxyamine midchain function in polymer polymer conjugation reactions with azide-terminated polymers, yielding 3-arm star (co)polymers via the Cu-catalyzed alkyne/azide cycloaddition reactions. The successful formation of star-block co- and homopolymers is confirmed by conventional size exclusion chromatography (SEC) as well as via hyphenated liquid absorption chromatography under critical conditions (LACCC)-SEC techniques. The synthetic approach reported herein demonstrates that click functional nitrones can efficiently be employed as macromolecular construction agents in modular reactions.