Diblock copolypeptides of poly(-benzyl-L-glutamate)-b-poly(-dodecyl-L-glutamate) (PBLG-b-PDLG) were synthesized by using the ring opening polymerization of N-carbonyl anhydride (NCA) method.N-hexylamine was used as the initiator

and the reaction was successfully operated in chloroform at 0℃ by adding the second NCAs sequentially after purification of the first segment of PBLG with amino terminal.The chemical contents of PBLG-b-PDLG were confirmed by 1H-NMR

which exhibits signals corresponding to the two different segmental side chains.The relative molecular mass and distribution were characterized by GPC

and the molecular weight distribution of the final PBLG-b-PDLG can be achieved to only 1.07~1.09.The secondary structure was examined by IR spectrum

which indicated the material exhibited -helical rod-like structure.The thermal behaviors of two block copolypeptides depend on the chemical composition

and both of them show thermotropic nature around 100℃ observed by polarizing microscope.No elimination of molecular alignment in magnetic orientated film takes place when heating above 100℃

therefore the phase structure of block copolymers differs from the random one of poly(-benzyl-L-glutamate-co--dodecyl-L-glutamate) exhibiting cholesteric twisting structure.The fan-shaped texture was observed in lyotropic solutions of the copolypeptide

indicating the smectic ordering existence.This appearance was believed to be contributed by its narrow molecular weight distribution.