Synthesis and Characterization of Poly(ethylene glycol)-block-Poly(Nα-Boc-L-tryptophan) copolymers

Amphiphilic diblock and triblock copolymers were synthesized from poly(ethylene glycol) (PEG) and N-alpha-Boc-L-tryptophan. A number of reaction conditions were investigated in order to achieve optimum yield and maximum chain extension for the newly formed block copolymers. Characterization of the novel copolymers was evaluated by means of ID and 2D solution state nuclear magnetic resonance (NMR), infrared (IR) spectroscopy and size exclusion chromatography (SEC). The 2D NMR investigation of the block copolymers provided evidence to suggest that protonation of the nitrogen atoms present along the newly formed peptide back bone was occurring when the solvent environment was under acidic conditions.