SYNTHESIS AND STRUCTURAL STUDY OF THE A-B-A-TYPE BLOCK COPOLYMER CONSISTING OF POLY(GAMMA-BENZYL L-GLUTAMATE) AS THE A-COMPONENT AND POLYBUTADIENE AS THE B-COMPONENT

A-B-A type triblock copolymers composed of γ-benzyl L-glutamate as the A component and butadiene as the B component were prepared. The method of synthesis consists of the polymerization of the γ-benzyl N-carboxy-L-glutamate anhydride initiated by the amine groups capped at both ends of the polybutadiene block which was prepared by bifunctional polymerization followed by a chemical modification of its living ends. From experimental results on the circular dichroism in ethylene dichloride solution, as well as from the infrared spectra measurements in the solid state, it has been found that the polypeptide chain block exists in the a-helical conformation in the same manner as poly(γ-benzyl L-glutamate). By using wide-angle X-ray diffraction and electron microscopy it could be shown that the block copolypeptides exhibit mesophases in different solvents. In this case, polybutadiene chains are in random coil conformation and form domains embedded in the matrix phase formed by the poly(γ-benzyl L-glutamate) chains in the a-helical conformation. © 1979, American Chemical Society. All rights reserved.