Alcohol Substrates Research Articles

Physically Transient Resistive Switching Memory With Material Implication Operation

In this letter, physically transient resistive switching devices with structure of Mg/SiO2/W for logic operation were proposed for the first time. Despite the desirable nonvolatile memory characteristics, the dissolvable memory devices could be used to achieve material implication function. Meanwhile, the transient memory arrays were transferred onto a dissolvable poly (vinyl alcohol) substrate by water-assisted transfer printing technique, and the transient system was capable of dissociating in deionized water after 20 min. This transient Mg/SiO2/W device demonstrates the great potential in future in-memory logic computing systems and secure electronic applications.

An Efficient Approach to Phosphorylated Isoindoline Fused with Triazoles via Zn-Catalyzed Cascade Cyclization of 2-Propynol Benzyl Azides and Diarylphosphine Oxides.

An efficient approach for the synthesis of phosphorylated isoindoline fused with triazoles via Zn(OTf)2-catalyzed cascade cyclization of easily prepared ortho–propynol benzyl azides and diarylphosphine oxides is developed. The transformation occurred smoothly in moderate to excellent yields and tolerated various propargylic alcohol substrates.

Three- and two-site heteropolyoxotungstate anions as catalysts for the epoxidation of allylic alcohols by H2O2 under biphasic conditions: Reactivity and kinetic studies of the [Ni3(OH2)3(B-PW9O34){WO5(H2O)}]7−, [Co3(OH2)6(A-PW9O34)2]12−, and [M4(OH2)2(B-PW9O34)2]10− anions, where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)

The trimetallic phosphopolyoxotungstate anions [Ni3(OH2)3(B-PW9O34){WO5(H2O)}]7− and [Co3(OH2)6(A-PW9O34)2]12− have been studied as epoxidation catalysts for oxygen transfer from 30% H2O2 to a range of allylic alcohols under biphasic conditions (1,2-dichloroethane/H2O) at 15 °C. The reaction mechanism involves coordination of an allylic alcohol at an M(II) site in each case, prior to transfer of a peroxy oxygen from an adjacent W(O2) site. The latter is formed from a terminal W = O unit by reaction with H2O2. Evidence of W(O2) formation was obtained through IR studies. The W(O2) group forms the epoxide by transfer of an oxygen atom to the CC bond of the coordinated allylic alcohol. Kinetic studies using 3-methyl-2-buten-1-ol as the allylic alcohol substrate have been modelled with all three metal sites catalytically active. The reaction involves an autocatalysis mechanism involving an induction period, which can be rationalised by proposing not only coordination of the allylic alcohol to M(II), but also the product hydroxy epoxide, both through their –OH groups. The autocatalysis is generated by formation of the W(O2) group adjacent to a coordinated hydroxy epoxide, which competes with coordination of allylic alcohol. The mechanism requires some twenty-one steps involving just the generic steps listed above, with all three metal sites catalytically active. Temperature-dependent kinetic studies and subsequent Eyring analyses have shown that the Co(II)-containing catalyst is the most active of the two. Analogous studies of the epoxidation of 3-methyl-2-buten-1-ol by the two-site [M4(OH2)2(B-PW9O34)2]10− ions as catalysts, where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II), at 15 °C gave an order of reactivity of Cu(II) > Ni(II) > Zn(II), Co(II), Mn(II), which mostly mimics the natural order of stability constants (the Irving-Williams series), suggesting that the formation of the allylic alcohol complexes play a dominant role in this series of related complex anions, with greater replacement of water by allylic alcohol leading to greater reactivity.

A flexible, scalable, and self-powered mid-infrared detector based on transparent PEDOT: PSS/graphene composite

A flexible, self-powered and semi-transparent mid-infrared photodetector is demonstrated with graphene and poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT: PSS) composite on poly vinyl alcohol (PVA) substrate. The effective dispersion of graphene nanoplatelets within polymer chains has yielded a low requisite loading of graphene – only 3 wt% for the implement of a detector with optimized photo-thermoelectric effect, high flexibility and high transparency. Under a broadband infrared radiation with peak wavelength at 7.8 μm, 1.4 × 107 cm Hz1/2 W−1 photo detectivity is achieved in composite detector, which is 22 times higher than pure PEDOT: PSS. The demonstrated detector array exhibits good optical transparency of 63% and is capable of being bent to a radius of 1 mm due to strong interaction between composite film and PVA substrate. These features make this scalable mid-infrared photodetector very promising as next-generation optoelectronics.

Targeted Development of Sustainable Green Catalysts for Oxidation of Alcohols via Tungstate-Decorated Multifunctional Amphiphilic Carbon Quantum Dots.

Achieving green and sustainable chemical processes by replacing organic solvents with water has always been one of the green chemistry goals and a challenging topic for chemists. However, the poor solubility of organic materials is a major limitation to achieving this goal, especially in alcohol oxidation. In this contribution, the development and design of amphiphilic catalysts via abundant, safe, cheaper, and more biocompatible sources have received notable attention. To this purpose, herein, our group successfully synthesized a new multifunctional amphiphilic carbon quantum dot (CQD) composed of 1-aminopropyl-3-methyl-imidazolium chloride ([APMim][Cl]), dodecylamine (DDA), and citric acid (CA) (denoted as CQDs@DDA-IL/Cl) using a one-pot hydrothermal route. The CQDs@DDA-IL/Cl was then utilized as an amphiphilic stabilizer for anchoring tungsten ions using an anion-exchange method (marked as CQDs@DDA-IL/W). The CQDs@DDA-IL/W as a reusable catalyst selectivity mediated the oxidation of alcoholic substrates with stoichiometric H2O2 in water solvent. The extraordinary performance of our catalyst was attributable to the coexistence of ionic liquid (IL) and DDA upon the surface of the CQDs@DDA-IL/W, which plays a main duty in the hydrophobic/hydrophilic balance, and significantly increase the catalyst compatibility in the aqueous medium with the purpose of removing organic solvents. As a result, the great mass transfer occurs in the two-phase medium using this amphiphilic nanocatalyst without any phase transfer catalyst (PTC) or other additives. The 100% selectivity, excellent turnover number (TON) and turnover frequency (TOF), high yield, almost complete and fast conversion of alcohol to the desired aldehydes and ketones without more oxidation, and easy and no-trouble isolation of product and catalyst are outstanding features of this catalytic system.

Effect of light irradiation on esterification of oleic acid with ethanol catalyzed by immobilized Pseudomonas cepacia lipase

The present study demonstrates the effect of light irradiation on the esterification of oleic acid catalyzed by immobilized Pseudomonas cepacia lipase. The reaction rates of all the experiments under light irradiation were found to be higher than dark conditions. The kinetics of reactions supported the Ping‐Pong Bi‐Bi mechanism with dead end inhibition by both the alcohol and acid substrates. Moreover, circular dichroism (CD) spectroscopy was used to analyze the effect of light on lipase enzyme. The CD spectroscopic studies confirmed that the conformational changes in the secondary structure of the lipase enzyme increased the reaction rate of light‐illuminated experiments, which might have opened up the active sites of enzymes and thus, resulted in higher reaction rates compared to dark reactions. These results have successfully demonstrated that the light illumination positively influenced the rate of P. cepacia enzyme‐catalyzed esterification reactions.

Properties enhancement of graphene and chemical reduction silver nanoparticles conductive inks printed on polyvinyl alcohol (PVA) substrate

Inkjet printing of conductive ink on flexible substrates is emerging as an attractive technology for wide variety applications. In this study, graphene and silver nanoparticles (AgNPs) conductive inks were printed on polyvinyl alcohol (PVA) substrates by inkjet printer. Effect of different solvents, printing cycles and annealing time on the performance of conductive ink was investigated. Three different groups of solvents were used to prepare the conductive ink; deionized water (DI): ethylene glycol (EG): glycol (G), isopropyl alcohol (IA): ethylene glycol (EG): glyceol (G) and dimethylformamide (DMF): Ethylene glycol (EG): Glyceol (G). DMF: EG: G solutions produced conductive ink with higher stability, wettability and electrical conductivity compared to other conductive ink formulations. It was observed that increased of printing cycles (from 1 to 5) times and annealing time (from 0 to 30) min had increase the electrical conductivity. During stretching, graphene conductive ink on PVA substrate shows lower electrical conductivity reduction compared to that of AgNPs conductive ink. Flaky shape of graphene able to maintain the conductive paths under loading condition.

Dynamic Self-Assembly of Polyelectrolyte Composite Nanomaterial Film.

The aim of this study is not only to investigate the feasibility of using PAH (polyallylamine hydrochloride) and PSS (poly styrene-4-sulfonic acid sodium salt) to prepare a film via a layer by layer self-assembly process entrained with silver nanoparticles, but also to show that the silver nanoparticles crystalline structure can be defined and deposited on the surface of the substrate in the desired alignment structure and manner, which is of great help to research on the LBL method in the cellulose field. The effect of outermost layer variation, assembly layers, and composition of multilayers on the formation of the LBL structure on a nanofibrillated cellulose (NFC)/polyvinyl alcohol (PVA) substrate was investigated. The deposition of PAH and PSS was monitored by Fourier-transform infrared spectroscopy (FT-IR). The morphology of the LBL film layers was observed by scanning electron microscope (SEM) and atomic force microscope (AFM). Furthermore, thermal degradation properties were investigated by thermogravimetric analysis (TGA), and physical properties of multilayer films were tested by a universal mechanical tester. The results reveal that PAH and PSS can be readily deposited on a NFC/PVA substrate by using LBL methodology to prepare self-assembled polyelectrolyte multilayer films. The surface morphology of the LBL composite changed from negative to positive charged depending on the final LBL treatment. Also, according to SEM and AFM analysis, silver nanoparticles were well dispersed in the (PAH/PSS) film, which significantly improved the thermal stability of the composite films.

3-BocNH-ABNO-catalyzed aerobic oxidation of alcohol at room temperature and atmospheric pressure

A transition-metal-free catalytic system has been developed for selective transformation of alcohol to aldehydes or ketones. The reactions were performed with 3-(tert-butoxycarbonylamino)-9-azabicyclo[3.3.1]nonane N-oxyl (3-BocNH-ABNO) as the catalyst, NaNO2 as the co-catalyst, molecular oxygen as the terminal oxidant, and AcOH as the solvent under room temperature. This catalytic system exhibited broad functional group tolerance. A series of alcohol substrates, including primary and secondary benzylic alcohols, heteroaromatic analogues, primary and secondary aliphatic alcohols, could be converted into their corresponding aldehydes and ketones in good conversions and selectivities.

Sub-kilogram-scale synthesis of highly dispersible zirconia nanoparticles for hybrid optical resins

Abstract We report the synthesis of highly dispersible zirconia (ZrO2) nanoparticles in sub-kilogram-scale by hydrothermal process coupled with alkaline hydrogen peroxide (AHP) treatment, with detailed studies on the effects of experimental parameters. Under optimized experimental condition, which was hydrothermal reaction at 110 °C for 6 h with mole ratio of sodium hydrate to zirconium carbonate basic in reactants as 2.3, pure-phase cubic-ZrO2 nanoparticles are obtained. Followed by AHP treatment of the ZrO2 nanoparticles at 50 °C for 5 h in 0.4 M hydrogen peroxide and 4 M sodium hydrate, the dispersibility of ZrO2 nanoparticles in aqueous suspension was enhanced due to the introduced Zr-OH groups on the surface. ZrO2 nanodispersion with solid content of 37 wt% in aqueous solution exhibited a uniform hydrodynamic size of 14.15 ± 5.834 nm and was stable for over six months without significant aggregates. Transparent hybrid optical resins with tunable refractive index in the range of 1.55–1.71 were prepared by solution blending method using ZrO2 nanoparticles as composite fillers in polyvinyl alcohol substrate. Compared with pure polyvinyl alcohol resin, the hybrid resin exhibits significant enhanced mechanical properties. Sub-kilogram-scale preparation of highly aqueous dispersible ZrO2 nanoparticles offers possibility for practical applications.

Highly efficient polymer-based nanoreactors for selective oxidation of alcohols in water

In this study, we demonstrate the fabrication of thermo-responsive polymer-based TEMPO nanoreactors and their application in the catalytic selective oxidation of alcohols as a highly efficient and recoverable catalyst in aqueous media. First, a diblock amphiphilic copolymer NHS-P(MMA25-b-OEGMA75) consisting of poly(methyl methacrylate) (PMMA) and poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA300) with a terminal N-hydroxysuccinimide (NHS) activated ester was synthesized utilizing reversible addition–fragmentation chain transfer polymerization (RAFT) techniques. Free radical 2,2,6,6,-tetramethyipiperidinooxy (TEMPO) was then introduced into the end of the copolymer based on activated ester functionalization to afford the temperature responsive polymer-supported catalyst TEMPO-P(MMA25-b-OEGMA75). Next, core-shell TEMPO nanoreactors were formed through self-assembly of the amphiphilic block polymers in deionized water. The morphology of the nanoreactors was well characterized by dynamic light scattering (DLS) and scanning electron microscopy (SEM). The nanoreactors were then successfully applied in the selective oxidative of alcohols in water. A variety of aldehydes and ketones were achieved in excellent yields and selectivities in high reaction rates with low catalyst loading. The high efficiency in catalysis of the nanoreactors may attributed to the ideal environment where enhancing the interactions between the catalyst and the alcohol substrate, mimicking the environment of enzymes. The thermo-responsive polymer-based nanoreactors could be conveniently recovered in the temperature above the LCST of the polymer after extraction of product from the reaction mixture. This strategy provides an effective and cleaner way for the selective oxidative of alcohols in organic synthesis and industrial application.

Catalytic Ring Expansions of Cyclic Alcohols Enabled by Proton-Coupled Electron Transfer.

We report here a catalytic method for the modular ring expansion of cyclic aliphatic alcohols. In this work, proton-coupled electron transfer activation of an allylic alcohol substrate affords an alkoxy radical intermediate that undergoes subsequent C-C bond cleavage to furnish an enone and a tethered alkyl radical. Recombination of this alkyl radical with the revealed olefin acceptor in turn produces a ring-expanded ketone product. The regioselectivity of this C-C bond-forming event can be reliably controlled via substituents on the olefin substrate, providing a means to convert a simple N-membered ring substrate to either n+1 or n+2 ring adducts in a selective fashion.

A highly sensitive biodegradable pressure sensor based on nanofibrous dielectric

High performance biodegradable electronic devices are becoming popular due to their enormous applications as biomedical implants or short term communication devices. They are biocompatible and eco-friendly. For example wearable or implantable biodegradable pressure sensors are very useful for cardiovascular or blood flow monitoring. But unfortunately very few previous researches have focused on developing biodegradable pressure sensors. Here we propose a composite of Polylactic-co-glycolic acid (PLGA) and Polycaprolactone (PCL) for biodegradable piezo-capacitive pressure sensor fabrication for low pressure measurement in tactile ranges of (0 < P < 5 kPa). An electrospun PLGA-PCL composite membrane has been used as elastomeric dielectric sandwiched between two biodegradable iron-zinc (Fe-Zn) bilayer electrodes, deposited on degradable Polyvinyl alcohol (PVA) substrate using electron beam deposition, and encapsulated in PLGA thin films for device fabrication. PLGA-PCL nanofibrous dielectric membrane is highly compressible and porous having tunable mechanical as well as dielectric properties and has been reported first ever for biodegradable pressure sensor application. The sensitivity of the sensor was found to be 0.863 ± 0.025 kPa−1 in the low pressure region (0 < P ≤ 1.86 kPa) which is quite high as compared to previous literature on biodegradable sensors so far while it adapted to a value of 0.062 ± 0.005 kPa−1 for high pressure region (1.86 kPa < P ≤ 4.6 kPa). The lowest detected value was 1.24 Pa (at 10mgf). Sensor showed good average response and recovery times of 251 ms and 170 ms respectively. In vitro degradation studies of the sensor were performed in PBS solution and sensor lost 60% of its initial weight during first two weeks of degradation and continued to degrade even after that. After one week of incubation sensor showed a 19.5% decrease in low pressure measurement range while there was no significant difference in upper detection range. It has been used to measure the arterial pulse wave on wrist and a 4 × 4 pressure sensor array was made to demonstrate its use in mapping different pressure points.

Synaptic-functional and fully water-soluble transient memristor made from materials compatible with semiconductor technology

A synaptic-functional and fully water-soluble physically transient device based on a Cu/amorphous Si/W memristor on a poly(vinyl alcohol) substrate is reported. The constituent materials of the device are all compatible with semiconductor technology, and Cu with a dissolution rate of 0.417 nm h−1 in deionized water can be used as an alternative metal material for transient electronics. In addition, the physically transient behavior of the memristor with synaptic function shows that the disintegration process of the device can be completed after immersion in water for only about 6 min. The proposed transient device is potentially suitable for secure neuromorphic computing applications.

Physically Transient Memristive Synapse With Short-Term Plasticity Based on Magnesium Oxide

In this letter, fully transient artificial synapses based on magnesium oxide memristors with short-term plasticity (STP) were proposed for the first time. Typical physiological reactions related to STP including pair-pulse facilitation and pair-pulse depression were demonstrated in such a transient synaptic device. Importantly, water-assisted transfer printing method was employed to transfer the dissolvable synaptic arrays onto bioresorbable poly (vinyl alcohol) substrate to form a fully transient system, which finally disintegrated in deionized water within 30 min. This transient synaptic emulator possesses great potential in security neuromorphic computing and environmentally resorbable applications.

HFIP Solvent Enables Alcohols To Act as Alkylating Agents in Stereoselective Heterocyclization.

A new method for the stereoselective synthesis of highly functionalized oxygen heterocycles using allyl or benzyl alcohols as alkylating agents is presented. The process is efficient and atom economic, generating water as the only stoichiometric byproduct. Substoichiometric amounts of Ti(OiPr)4 in HFIP solvent are key to this reactivity, and the method tolerates a broad substitution pattern on both the alcohol initiator and homoallylic alcohol substrate. Preliminary mechanistic studies reveal in situ formation of a titanium complex with HFIP which may initiate the cyclization reaction. Further stereoselective functionalization of the products allows access to a diverse range of interesting heterocyclic structures.

Compartmentalized Nanoreactors for One-Pot Redox-Driven Transformations

This contribution introduces poly(2-oxazoline)-based shell cross-linked micelles (SCMs) as nanoreactors to realize one-pot redox-driven deracemizations of secondary alcohols in aqueous media. TEMPO and Rh-TsDPEN moieties are spatially positioned into the hydrophilic corona and the hydrophobic micelle core, respectively. TEMPO catalyzes the oxidation of racemic secondary alcohols into ketones, while Rh-TsDPEN catalyzes the asymmetric transfer hydrogenation (ATH) of these ketones to afford enantioenriched secondary alcohols. Both catalysts, the Rh-TsDPEN complex and TEMPO, are incompatible with each other and the SCMs are designed to provide indispensable catalyst site isolation. Kinetic studies show that the SCMs enhance the reactivity of the immobilized catalysts, in comparison to those for the unsupported analogues under the same reaction conditions. Our nanoreactors can perform deracemizations on a broad range of secondary alcohol substrates and are reusable in a continuous manner while maintaining high...

Functionalized water soluble nanomaterials and their applications in wirelessly destructible programmed flexible transient photodetectors

Electronic systems that can respond to the user-defined circumstances from a distant location hold enormous potential in disposable devices, secured memories, restorable environmental monitoring etc. related applications which cannot be achieved by conventional silicon technology. This paper is the first demonstration of wirelessly destructible ultraviolet photodetector based on Itaconic acid functionalized water soluble ZnS on flexible polyvinyl alcohol (PVA) substrate wherein all of the device elements dissolve and/or disintegrate upon immersion in water triggered using smartphone assisted Android application. The user can wirelessly destroy the sensor anytime or the sensor can be programmed to be destroyed after performing its task. Use of graphene as both contacts as well as a transport layer enables superior photodetection while making the fabrication simple, low-cost and cleanroom free which disintegrates from the device upon dissolution in water. The fabricated transient, flexible photodetector exhibited a remarkable responsivity of 1.08 mA/W and rise time and fall times of 6.1 s and 8.23 s respectively which could be ascribed to the large electric field created at the ZnS/graphene schottky barrier. Dissolution and disintegration of the fabricated sensor demonstrate complete transience in 10 mins. The study presented here opens up numerous possibilities for applications of wireless transient photodetectors in environmental monitoring, health care, security and consumer electronics.

Pull-off and friction forces of micropatterned elastomers on soft substrates: the effects of pattern length scale and stiffness.

The adhesiveness of biological micropatterned adhesives primarily relies on their geometry (e.g., feature size, architecture) and material properties (e.g., stiffness). Over the last few decades, researchers have been mimicking the geometry and material properties of biological micropatterned adhesives. The performance of these biomimetic micropatterned adhesives is usually tested on hard substrates. Much less is known about the effect of geometry, feature size, and material properties on the performance of micropatterned adhesives when the substrate is deformable. Here, micropatterned adhesives of two stiffness degrees (Young’s moduli of 280 and 580 kPa) were fabricated from poly(dimethylsiloxane) (PDMS) and tested on soft poly(vinyl alcohol) (PVA) substrates of two stiffness degrees (12 and 18 kPa), and on hard glass substrates as a reference. An out-of-the-cleanroom colloidal lithographic approach was successfully expanded to fabricate adhesives with two geometries, namely dimples with and without a terminal layer. Dimples without a terminal layer were fabricated on two length scales, namely with sub-microscale and microscale dimple diameters. The cross section of samples with a terminal layer showed voids with a spherical shape, separated by hourglass-shaped walls. These voids penetrate the terminal layer, resulting in an array of holes at the surface. We found that on soft substrates, generally, the size of the dimples did not affect pull-off forces. The positive effects of sub-microscale features on pull-off and friction forces, such as defect control and crack trapping, as reported in the literature for hard substrates, seem to disappear on soft substrates. The dimple geometry with a terminal layer generated significantly higher pull-off forces compared to other geometries, presumably due to interlocking of the soft substrate into the holes of the terminal layer. Pull-off from soft substrates increased with the substrate stiffness for all tested geometries. Friction forces on soft substrates were the highest for microscale dimples without a terminal layer, likely due to interlocking of the soft substrate between the dimples.

High-Throughput Production of Heterogeneous RuO2/Graphene Catalyst in a Hydrodynamic Reactor for Selective Alcohol Oxidation

We report on the high-throughput production of heterogeneous catalysts of RuO2-deposited graphene using a hydrodynamic process for selective alcohol oxidation. The fluid mechanics of a hydrodynamic process based on a Taylor–Couette flow provide a high shear stress field and fast mixing process. The unique fluidic behavior efficiently exfoliates graphite into defect-free graphene sheets dispersed in water solution, in which ionic liquid is used as the stabilizing reagent to prevent the restacking of the graphene sheets. The deposition of RuO2 on a graphene surface is performed using a hydrodynamic process, resulting in the uniform coating of RuO2 nanoparticles. The as synthesized RuO2/IL–graphene catalyst has been applied efficiently for the oxidation of a wide variety of alcohol substrates, including biomass-derived 5-hydroxymethylfurfural (HMF) under environmentally benign conditions. The catalyst is mechanically stable and recyclable, confirming its heterogeneous nature.