Abstract
An amphiphilic block copolymer of poly(L-leucine-co-ethylene glycol)(PLeu40-PEG114) was prepared and spread at an air-water interface to form a stable monolayer. α-helical conformation of PLeu segment of the block copolymer in the monolayer was confirmed by the circular dichroism (CD) and FT-IR measurements. The surface pressure-area (π-A) isotherm of the monolayer indicated that the α-helix rod of the PLeu segment oriented slightly normal to the air-water interface by increasing the surface pressure of the monolayer. The PLeu40-PEG114 monolayer could be transferred on the Au surface, and the molecular orientation of PLeu helix rods was estimated by FT-IR reflection absorption spectroscopy (FT-IR/RAS) measurements. As a result, it was also confirmed that α-helix rod of the block copolymer oriented slightly normal to the Au surface. Therefore, PEG segment in the block copolymer was essential for the tilting of the PLeu helix rod at the interface, however, which may act in turn as a fault for the further standing of helix rod by the additional compression of the monolayer.
