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Abstract Functional oxides have extensively been investigated as a promising class of materials in a broad range of innovative applications. Harnessing the novel properties of functional oxides in micro‐ to nano‐scale applications hinges on establishing advanced fabrication and manufacturing techniques able to synthesize these materials in an accurate and reliable manner. Oxidative scanning probe lithography (o‐SPL), an atomic force microscopy (AFM) technique based on anodic oxidation at the water meniscus formed at the tip/substrate contact, not only combines the advantages of both “top‐down” and “bottom‐up” fabrication approaches, but also offers the possibility of fabricating oxide nanomaterials with high patterning accuracy. While the use of self‐assembled monolayers (SAMs) broadened the application of o‐SPL, significant challenges have emerged owing to the relatively limited number of SAM/solid surface combinations that can be employed for o‐SPL, which constrains the ability to control the chemistry and structure of oxides formed by o‐SPL. In this work, a new o‐SPL technique that utilizes room‐temperature ionic liquids (RTILs) as the functionalizing material to mediate the electrochemistry at AFM tip/substrate contacts is reported. The results show that the new IL‐mediated o‐SPL (IL‐o‐SPL) approach allows sub‐100 nm oxide features to be patterned on a model solid surface, namely steel, with an initiation voltage as low as −2 V. Moreover, this approach enables high tunability of both the chemical state and morphology of the patterned iron oxide structures. Owing to the high chemical compatibility of ILs, which derives from the possibility of synthesizing ILs able to adsorb on a wide variety of solid surfaces, IL‐o‐SPL can be extended to other material surfaces and provide the opportunity to accurately tailor the chemistry, morphology, and electronic properties within nanoscale domains, thus opening new pathways to the development of novel micro‐ and nano‐architectures for advanced integrated devices. 

While ionic liquids (ILs) have attracted much attention as potential next-generation lubricant additives, their implementation in oil formulations has been hindered by their limited solubility in hydrocarbon fluids and corrosivity. Here, we encapsulate an oil-insoluble IL that has been studied in lubrication science, namely 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([HMIM][TFSI]), within poly(ethylene glycol dimethacrylate-buytl methacrylate copolymer) (poly(EGDM-c-BMA)) microshells using a mini-emulsion polymerization process. The synthesized poly(EGDM-c-BMA)-encapsulated [HMIM][TFSI] microparticles are shown to be dispersible in a non-polar, synthetic oil (i.e., poly-α-olefin). Tribological experiments indicated that the microcapsules act as an additive reservoir that reduces friction by releasing the encapsulated IL at the sliding interface following the mechanical rupture of the polymer shell. X-ray photoelectron spectroscopy (XPS) measurements provided evidence that [HMIM][TFSI] does not tribochemically react on steel surfaces to create a reaction layer, thus suggesting that this IL reduces friction by generating a solid-like, layered structure upon nanoconfinement at sliding asperities, as proposed by previous nanoscale studies. The results of this work do not only provide new insights into the lubrication mechanism of ILs when used as additives in base oils in general, but also establish a new, broadly-applicable framework based on polymer encapsulation for utilizing ILs or other compounds with limited solubility as additives for oil formulations. 

In this work, we perform atomic force microscopy (AFM) experiments to evaluate in situ the dependence of the structural morphology of trihexyltetradecylphosphonium bis(2-ethylhexyl) phosphate ([P 6,6,6,14 ][DEHP]) ionic liquid (IL) on applied pressure. The experimental results obtained upon sliding a diamond-like-carbon-coated silicon AFM tip on mechanically polished steel at an applied pressure up to 5.5 ± 0.3 GPa indicate a structural transition of confined [P 6,6,6,14 ][DEHP] molecules. This pressure-induced morphological change of [P 6,6,6,14 ][DEHP] IL leads to the generation of a lubricious, solid-like interfacial layer, whose growth rate increases with applied pressure and temperature. The structural variation of [P 6,6,6,14 ][DEHP] IL is proposed to derive from the well-ordered layering of the polar groups of ions separated by the apolar tails. These results not only shed new light on the structural organization of phosphonium-based ILs under elevated pressure, but also provide novel insights into the normal pressure-dependent lubrication mechanisms of ILs in general.