Surface structure of ultrathin copolymer films of ferroelectric vinylidene fluoride (70%) with trifluoroethylene (30%) on graphite

The structure and local structural distortions, through the polarization manipulation, of crystalline films of ferroelectric vinylidene fluoride (70%) with trifluoroethylene (30%) [P(VDF-TrFE)] copolymer on graphite were studied by scanning tunneling microscopy (STM). A quasispiral twist in C[Single Bond]C bonds with rotations about the polymer chain axis was observed by high-resolution STM, indicating a surface relaxation of the strained copolymer films. Such a relaxation behavior appears to be linked to the observed local dipole rotations accompanied by the reversal of the local polarization with biasing the STM tip. A structure model is proposed based upon the observations