The fractionation of crude-oil mixtures through distillation is a large-scale, energy-intensive process. Membrane materials can avoid phase changes in such mixtures and thereby reduce the energy intensity of these thermal separations. With this application in mind, we created spirocyclic polymers with N-aryl bonds that demonstrated noninterconnected microporosity in the absence of ladder linkages. The resulting glassy polymer membranes demonstrated nonthermal membrane fractionation of light crude oil through a combination of class- and size-based “sorting” of molecules. We observed an enrichment of molecules lighter than 170 daltons corresponding to a carbon number of 12 or a boiling point less than 200°C in the permeate. Such scalable, selective membranes offer potential for the hybridization of energy-efficient technology with conventional processes such as distillation.
We report herein the design of a light-responsive gatekeeper for smart nitric oxide (NO) delivery. The gatekeeper is composed of a pH-jump reagent as an intermediary of stimulus and a calcium phosphate (CaP) coating as a shielding layer for NO release. The light irradiation and subsequent acid generation are used as triggers for uncapping the gatekeeper and releasing NO. The acids generated from a light-activated pH-jump agent loaded in the mesoporous nanoparticles accelerated the degradation of the CaP-coating layers on the nanoparticles, facilitating the light-responsive NO release from diazeniumdiolate by exposing a NO donor to physiological conditions. Using the combination of the pH-jump reagent and CaP coating, we successfully developed a light-responsive gatekeeper system for spatiotemporal-controlled NO delivery.
We have investigated the inkjet-printing of TiO 2 films for the fabrication of dye-sensitized solar cells (DSSCs). In order to realize the uniform printing of TiO 2 films, the co-solvent ink was designed by introducing a drying agent to the ink. This co-solvent ink induces a circulating flow within ink droplets and leads to the uniform lines and films by inkjet. A theoretical model was used to predict the optimal ink-droplet pitches for the inkjet-printing of uniform lines. This model also contributes to the formation of uniform films since they are filled with the inkjet-printed lines. The inkjet-printed TiO 2 films were used as photoelectrodes for dye-sensitized solar cells. The thickness of the inkjet-printed TiO 2 films was varied to optimize the photovoltaic performance of DSSCs. Since no organic additives were introduced into the TiO 2 inks, the feasibility of reducing the annealing temperature for TiO 2 photoelectrodes was investigated. This study may suggest an opportunity to fabricate DSSCs at low temperature.
A new process for directed block co-polymer self-assembly (DSA), AZ ® SMART™, for high resolution line and space patterning was introduced. The SMART process started with photoresist trench patterns generated through common photolithographic processes on top of a thin crosslinked neutral layer. A reactive ion etching (RIE) process removed the neutral layer at bottom of the resist trenches and followed by a resist stripping step which completely removed the resist material and uncovered the neutral surface protected by the resist film during etching step. DSA performances of the resultant SMART chemical pre-patterns without or with extra pinning material brushing step were compared. Results indicated that pinning material enhanced chemical pre-pattern directing power for DSA performance. The chemical prepattern without pinning material provided well aligned DSA performance for some specific pre-pattern structure and DSA multiplication factor, but it lacked general performance stability. On the other hand, process with added pinning material was demonstrated with stable performance for variable pre-pattern pitches with different DSA multiplication factors. SMART DSA pattern profile and its pattern etching transfer into hard masks were investigated.
Transition metal dichalcogenides (TMDs) are of great interest owing to their unique properties. However, TMD materials face two major challenges that limit their practical applications: contact resistance and surface contamination. Herein, a strategy to overcome these problems by inserting a monolayer of hexagonal boron nitride (h‐BN) at the chromium (Cr) and tungsten disulfide (WS2) interface is introduced. Electrical behaviors of direct metal–semiconductor (MS) and metal–insulator–semiconductor (MIS) contacts with mono‐ and bilayer h‐BN in a four‐layer WS2 field‐effect transistor (FET) are evaluated under vacuum from 77 to 300 K. The performance of the MIS contacts differs based on the metal work function when using Cr and indium (In). The contact resistance is significantly reduced by approximately ten times with MIS contacts compared with that for MS contacts. An electron mobility up to ≈115 cm2 V‐1 s‐1 at 300 K is achieved with the insertion of monolayer h‐BN, which is approximately ten times higher than that with MS contacts. The mobility and contact resistance enhancement are attributed to Schottky barrier reduction when h‐BN is introduced between Cr and WS2. The dependence of the tunneling mechanisms on the h‐BN thickness is investigated by extracting the tunneling barrier parameters.
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