Targeting 2D Nanostructures in Phase-Separated Materials through Molecular Design.

Oligomeric materials that spontaneously order into 2D morphologies are of interest for a broad range of applications. In the absence of molar mass dispersity, these materials are perfectly defined at the molecular level and have been shown to form sub-10 nm nanostructures. Consequently, such nanostructured oligomers exhibit intriguing properties for e.g., photophysical applications depending on their constituents. However, ab initio prediction of the obtained morphologies remains challenging. Therefore, we herein report a systematic approach to investigate the influence of molecular architecture as well as the influence of the pendant chain attached to the core on spontaneously phase-separated nanostructures. We synthesized 20 molecules containing discrete oligodimethylsiloxane (oDMS) and four different crystalline units, varying their molecular architecture and pendant chains. Lamellar morphologies were obtained most reliably using telechelic and head-tail architectures with symmetric peripheral crystalline blocks. Contrarily, these architectures in conjunction with asymmetric cores as well as core-centered architectures resulted primarily in columnar morphologies. This systematic investigation of the design parameters for 2D nanostructures aids the development of next-generation materials, e.g., nanoscale optoelectronics.