A photo-induced nitroxide trapping method to prepare α,ω-heterotelechelic polymers

Abstract

Two types of photoactive polymers with an alkoxyphenyl ketone moiety at their backbone centers were synthesized through atom transfer radical polymerization. A facile protocol for preparing α,ω-heterotelechelic polymers was developed, employing nitroxide with different functional groups (e.g., hydroxyl, propargyl, glycidyl, and polyethylene glycol) coupled with macromolecular radicals generated via the Norrish-type I photoreaction under mild UV irradiation from the said polymers. Experimental conditions such as solvent effects and irradiaton time were investigated to optimize the efficiency of reaction functionality. The number-average molecular weights of the photoactive polymers and α,ω-heterotelechelic polymers were determined by gel permeation chromatography. Material structures were further confirmed by ¹H NMR and FT-IR spectroscopy. The end group activity of α,ω-heterotelechelic polymers obtained from this reaction was further demonstrated using the Cu-catalyzed azide–alkyne click reactions between PS-N₃ and polystyrene capped with a propargyl group.