Three-Component Bolaform Giant Surfactants Forming Lamellar Nanopatterns with Sub-5 nm Feature Sizes

Abstract

Nanopatterns with a sub-5 nm line width are of great interest due to their potential applications in nanotechnology. Herein, we report the design and synthesis of three-component bolaform giant surfactants that can assemble into three-phase-four-layer lamellar (LAM 3 ) structures with sub-5 nm feature sizes. These samples consist of central linear polystyrene (PS) chains with oligodimethylsiloxane-functionalized polyhedral oligomeric silsesquioxane (SiPOSS) at one end and perfluoroalkyl-functionalized POSS (FPOSS) at the other end. Phase separation occurs among three mutually incompatible components, leading to LAM 3 structures with relatively sharp interfaces and d -spacings of 12–19 nm. While the lamellar periodicity can be facilely tuned by changing the chain length of PS, the pitch widths of the POSS domains remain largely constant. Energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) were used to analyze the elemental distribution of the LAM 3 structures. After oxygen plasma treatment, the morphology converts into a hierarchical lamellar structure with extremely small Si-rich layers (∼2 nm in thickness). This work suggests that these bolaform giant surfactants are versatile counterparts of traditional triblock copolymers capable of undergoing rapid and strong phase separation at relatively low molecular weights toward unconventional nanostructures with small feature sizes.