TEM and STS studies of resorcinarene-passivated nanostructured interfaces
Abstract
Resorcin[4]arene derivatives have been investigated as insulating, self-assembled monolayers (SAMs) on atomically smooth Au substrates, and as surfactants for mediating the self-organization of colloidal Au and Co nanoparticles (NPs). Three projects will be discussed: (1) SAMs of dodecanethiol, octadecanethiol, and resorcinarene C10 tetrasulfide 1 on Au(111) have been characterized by scanning tunneling spectroscopy (STS) and evaluated for their potential as ultrathin resists. STS reveals that SAMs of 1 demonstrate a high electrical resistivity relative to the alkanethiol SAMs of similar thicknesses, comparable to that of silicon oxide. (2) Large gold NPs (16–170 nm) encapsulated by resorcinarene tetrathiol 2 can self-organize into 2D hexagonally close-packed arrays at air-water interfaces, and can be transferred onto carbon-coated substrates. Transmission electron microscopy (TEM) studies reveal that the particle spacing decreases with increasing particle size, an indication of increased van der Waals attraction. (3) Weakly ferromagnetic cobalt nanoparticles stabilized with resorcinarene 3 can self-assemble into bracelet-like rings with discrete particle count (typically 5–12 particles and 50–100 nm in diameter). Self-assembly of these nanoparticle “bracelets” is dependent on the magnetization of the nanoparticles; they can be assembled into chains by a sufficiently large applied field, but revert to bracelets upon thermodynamic equilibrium. The bracelets are shown to be distinct from the micrometer-sized rings created by rapidly evaporating films of dispersed nanoparticles, both with regard to ring size and to their mechanism of assembly.
Degree
Ph.D.
Advisors
Wei, Purdue University.
Subject Area
Organic chemistry|Materials science|Analytical chemistry
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