SYNTHESIS AND STRUCTURAL STUDY OF AN ABA BLOCK-COPOLYMER CONSISTING OF POLY(EPSILON-BENZYLOXYCARBONYL-L-LYSINE) AS THE A-BLOCK AND POLY(ETHYLENE OXIDE) AS THE B-BLOCK
Cs. Cho et al., SYNTHESIS AND STRUCTURAL STUDY OF AN ABA BLOCK-COPOLYMER CONSISTING OF POLY(EPSILON-BENZYLOXYCARBONYL-L-LYSINE) AS THE A-BLOCK AND POLY(ETHYLENE OXIDE) AS THE B-BLOCK, Macromolecular chemistry and physics, 195(6), 1994, pp. 2195-2206
ABA-type block copolymers composed of poly(epsilon-benzyloxycarbonyl-L
-lysine) (PCLL) as the A component and poly(ethylene oxide) as the B c
omponent were synthesized by polymerization of epsilon-benzyloxycarbon
yl-L-lysine N-carboxyanhydride initiated by primary amino groups locat
ed at both ends of the PEO chain. From circular dichroism measurements
in solution, as well as from infrared spectra measurements in the sol
id state, it was found that the polypeptide block exists in the alpha-
helical conformation, as in PCLL homopolymer. The intensity of wide-an
gle X-ray diffraction patterns of the block copolymers depends on the
PEO content and shows basically similar reflections as the PCLL homopo
lymer. The morphology examined by transmission electron microscopy and
differential scanning calorimetry revealed microphase-separated struc
ture.