Synthesis of pyrene end-capped A6 dendrimer and star polymer with phosphazene core via "click chemistry"

Abstract

Novel hexa-armed and pyrene (Pyr) end-capped phosphazene dendrimer [N 3P3-(Pyr)6] and star polymer with poly(ε-caprolactone) (PCL) arms [N3P3-(PCL-Pyr) 6] were prepared via two series of reactions. In these series, core-first approach was used starting from a hexa-hydroxy functional phosphazene derivative (N3P3-(OH)6). It was used as an initiator in the ring-opening polymerization of ε-caprolactone to prepare a hexa-armed PCL star polymer (N3P3-(PCL-OH)6). Hydroxyl functionalities of N3P3-(OH)6 and N3P3-(PCL-OH)6 were then successfully converted into bromide and azide, in turn. Further end-group modifications of azide functional dendrimer precursor (N3P3-(N3) 6) and star polymer (N3P3-(PCL-N 3)6) were achieved quantitatively via the Cu(I) catalyzed click reaction between azide functional groups and 1-ethynyl pyrene in the final step. Moreover, the pyrene end-capped phosphazene dendrimer and star polymer were used in noncovalent functionalization of multiwalled carbon nanotubes. © 2011 Wiley Periodicals, Inc.