Aminooxy and Pyridyl Disulfide Telechelic Poly(Polyethylene Glycol Acrylate) by RAFT Polymerization.

An efficient method to synthesize telechelic, bio-reactive polymers is described. Homotelechelic polymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization in one step by employing bifunctional chain transfer agents (CTAs). A bis-carboxylic acid CTA was coupled to N-BOC-aminooxy ethanol or pyridyl disulfide ethanol resulting in a bis-N-BOC-aminooxy CTA and a bis-pyridyl disulfide CTA, respectively. RAFT polymerization of polyethylene glycol (PEG) acrylate in the presence of both CTAs resulted in a series of polymers over a range of molecular weights (~8.4 kDa to 35.2 kDa; polydispersity indices, PDIs of 1.11 to 1.44) with retention of end-groups post-polymerization. The polymers were characterized by 1H NMR spectroscopy and gel permeation chromatography (GPC). Conjugations of small molecules and peptides resulted in homotelechelic polymer conjugates.