Synthesis and micellization behavior of stimuli-responsive polypeptide hybrid triblock copolymer

Polypeptide hybrid triblock copolymer, poly(L-glutamic acid)-b-poly(propylene oxide)-b-poly (L-glutamic acid) (PLGA-b-PPO-b-PLGA), was synthesized by the ring-opening polymerization of benzyl-L-glutamic N-carboxyanhydride (BLG-NCA) using poly(propylene glycol) bis(2-aminopropyl ether) as initiator, followed by the subsequent deprotection step. The obtained double hydrophilic triblock copolymer exhibits schizophrenic micellization behavior in aqueous solution upon dually playing with solution pH and temperature. The multi-responsive micellization behavior of this polypeptide hybrid triblock copolymer has been thoroughly investigated by H-1 NMR, laser light scattering (LLS), temperature-dependent optical transmittance, and circular dichroism spectroscopy (CD).