| The ring opening polymerization of aminoacid N-carboxyanhydrides ( NCAs) was applied to the synthesis of cylindrical polypeptide brushes by using the " grafting from" technique. The procedure included the following steps: (1) thermal polymerization of ME,HG,HL gave super-high molar mass mains with pendant protected amine groups; (2) subsequent removal of tert-butoxycarbonyl groups (Boc) of PME, PHG, PHL yielded polyinitiators (PME-BoC, PHL-Boc, PHG-Boc); (3) The ring opening polymerization of γ-benzyl-L-glutamate NCA using PME-Boc, PHL-Boc, PHG-Boc as polyinitiators yield cylindrical polypeptide brushes with poly-glutamate as side chains. (4) ~1HNMR,GPC,AFM investigation of the samples; By using this technique, the cylindrical polypeptide brushes with super-high molar mass as backbones (DP>10000) and poly-glutamate as side chains were successfully synthesized.The cylindrical brushes with Poly-Lysine (DP>5000) as backbones and Poly-glutamate as side chains were also synthesized. Meanwhile the polymerization of Y-benzyl-L-glutamate NCA by polyinitiators were studied respectively. Because of intermolecular hydrogen bond and intramolecular hydrogen bond these cylindrical brushes are poor soluble in common solvents except DMF and DMSO at high temperature. The peaks at 1.5-2.5 assigned to poly-glutamate were confirmed by ~1HNMR. The cylindrical brushes were then further characterized by scanning force microscopy. Single wormlike unimolecular nanocylinders were visualized on a mica surface. |
