Observation of Phase-Separated Nanometer Scale Molecular Domains in Mixed Self-Assembled Monolayers.

摘要

We demonstrate the phase separation into nanometer scale domains of two-component monolayers prepared by self-assembly on gold of CH3(CH2)15SH and CH3O2C(CH2)15SH, two similar, non-hydrogen bonding alkane thiols of identical alkyl chain length. By varying the fractions of the two components, we have learned to distinguish between domains of each molecule by scanning tunneling microscopy. These observations have important implications for both the scientific understanding of phase segregation in quasi-two-dimensional molecular mixtures and for applications of self-assembly in which the formation of spatially resolved mixed functional group surfaces is desired (targeted). Further, these observations provide a caveat with regard to the common assumption of complete mixing in multi-component self-assembled monolayers.