Liquid Acetone Research Articles

Dewetting of Stable Thin Polymer Films Induced by a Poor Solvent: Role of Polar Interactions

We investigate the room temperature instability and dewetting of ultrathin (<100 nm) stable polystyrene (PS) films induced by a poor solvent, such as acetone, on a higher energy silicon substrate without an oxide layer. Instability behavior is contrasted for thermal annealing and acetone-vapor annealing and by immersion under liquid acetone. The PS films that are stable under thermal annealing are rendered unstable to dewetting when contacted by acetone, notwithstanding the stabilizing apolar van der Waals interactions in all the three systems. Relatively high molecular weight films dewet only in the liquid acetone, but low molecular weight films dewet on contact with both vapor and liquid acetone. These findings indicate the role of polar interactions engendered by acetone in the film instability modified possibly by nanophase separation aided by the substrate and nucleative mechanisms. Liquid acetone greatly enhances the instability so that the number density of holes produced in liquid acetone is about 2 orders higher than in acetone vapor. In both of these cases, the scaling (N ∼ Hn) of the number of holes per unit area, N, with the film thickness, H, is found to be clearly different (n ∼ 2.5–2.7) from that seen in most of the previous studies on thermal dewetting (n ∼ 4). From the kinetics of hole growth, the slippage effect of PS chains can be observed in the solvent vapor-induced dewetting process but not in the dewetting under liquid acetone.

Poisoning of acetone to Pt and Au electrodes for electrooxidation of 2-propanol in alkaline medium

Running of direct 2-propanol fuel cell generates liquid acetone as the main product in the anode compartment. Its concentration continuously increases during cell operation. Its effect on the electrooxidation of 2-propanol at the anode catalyst deserves to be addressed. In this study, the influence of acetone concentration and reaction temperature on the electrooxidation of 2-propanol at Pt and Au electrode in alkaline electrolyte is investigated by cyclic voltammetry and chronoamperometry. The results show that the rate of 2-propanol electrooxidation at Pt and Au electrode is remarkably diminished with the increase of acetone concentration. When the concentration of acetone reaches 0.1molL−1, the oxidation current of 2-propanol at Pt and Au electrode decreases by around 50% and 30%, respectively. The effect of acetone can be attributed to its competitive adsorption with 2-propanol on electrodes surface, leading to the poison of electrodes. Increase of reaction temperature decreases the oxidation current of 2-propanol at Au electrode. Au electrode is more tolerant to acetone than Pt electrode at low acetone concentration. Results of this study suggest that new acetone insensitive electrocatalysts are needed for 2-propanol electrooxidation in alkaline electrolytes.

Studies on the resistive response of nickel and cerium doped SnO2 thick films to acetone vapor

Undoped and Ni, Ce-doped nanocrystalline tin oxide were synthesized by co-precipitation route. Doped as well as undoped SnO2 compositions revealed single phase structure without any impurity. The lattice constant of SnO2 increases and the grain size decreases with doping of Ni and Ce. The responses of the sensing elements are evaluated by measuring the resistance change upon exposure to various test gases such as liquid petroleum gas (LPG), acetone, ethanol and ammonia. In comparison to LPG, ethanol, and ammonia the response towards acetone vapor increases markedly on simultaneous doping of Ni and Ce. For acetone vapors with 500ppm at 300°C, the undoped SnO2 shows 31% response, while with individual Ni or Ce doping it increases to 38 and 60%, respectively, however with simultaneous doping of Ni and Ce there is a significant enhancement up to 92%. The results of gas sensing measurements reveal that the thick films deposited on alumina substrates using screen printing technique give selectively a high response of (87%) with fast recovery (∼1min) towards 100ppm acetone at 300°C.

Eddy-current-resistant SmCo5/CaF2 magnets produced via high-energy milling in polar and non-polar liquids

Processes of high-energy ball milling of SmCo5 alloys were compared for three single-liquid environments without using additional surfactants. Both coarsely grained as-cast and nanocrystalline pre-milled SmCo5 precursors showed tendency toward formation of thin flakes if milled in polar liquids (acetone and ethanol) in a marked contrast to milling in non-polar heptane. CaF2 dielectric powder added prior to milling in the polar liquids tends to become attached on the flake surfaces. Milling in heptane in the presence of CaF2 produces flake-like SmCo5 particles which with increasing the milling time are found to incorporate an increasing amount of CaF2. The SmCo5—5wt% CaF2 mixtures milled for the optimum time in both the polar and non-polar liquids were successfully hot-pressed into laminated composite magnets having intrinsic coercivity of 25–30kOe, maximum energy product of approximately 6.5MGOe and electrical resistivity of 500–600μΩcm, which is more than 7 times the resistivity of conventional Sm–Co magnets.

Partially premixed reacting acetone spray using LES and FGM tabulated chemistry

Large Eddy Simulations of dilute spray-air reacting two phase flow are performed following an Eulerian–Lagrangian approach. The method includes a full two-way coupling in which phase properties and spray source terms are interchanging between the two phases within each coupling time step. To achieve sub-grid scale closures in the filtered equations used for LES of the carrier phase, the Smagorinsky model with dynamic procedure is applied for the flow field while an eddy diffusivity approach is used for the scalar fluxes. The phase transition of droplets is captured using a non-equilibrium evaporation model. The evaporating droplets are tracked using a Langragian procedure. They are injected in a polydisperse manner and generated in time dependent boundary conditions. The combustion is described by a reaction progress variable and a mixture fraction as well as their variances in the line of the Flamelet Generated Manifold method. The ultimate objective of this work is to appraise the ability of this LES-based spray module developed here to retrieve the spray flow and combustion properties of the configuration under study. The configuration consists of a spray jet issued into a pilot flame and a co-flowing atmospheric air in which droplets traverse a pre-evaporation distance and release part of their mass before reaching the combustion zone. Thereby the spray pre-evaporation turns the combustion regime from diffusion to partially premixed. The fuel used is liquid acetone, which is modeled by a detailed reaction mechanism including 84 species and 409 elementary reactions. A series of spray established at different operating conditions are investigated, analyzed and compared. Analysis allows to gain a deep insight into the process ongoing. Comparisons include exhaust gas temperature, droplet velocities and corresponding fluctuations, droplet mean diameters and spray volume flux at different distances from the exit planes. An overall good agreement is reported.

Modeling Solvent Influence on Growth Mechanism of Nanoparticles (Au, Co) Synthesized by Surfactant Free Laser Processes

Co and Au nanoparticles have been synthesized by femtosecond laser ablation and fragmentation in various liquids (n-hexane, diethyl ether, toluene, 2-propanol, acetone, and methanol) to investigate their influences on the size of the generated particles. Results suggest that nanoparticle growth with the absence of surfactants occurs from light absorption by the colloids through diffusion coalescence and can be controlled by the solvent polarity, the processing time, and the laser power. Furthermore, the growth has been related to the electrostatic repulsion energy and to the change in the nanoparticle temperature due to the laser light absorption by using the DLVO theory. Nanosecond laser annealing of Au particles in methanol also confirms the proposed model.

Terahertz Frequency-Domain Spectroscopy Method for Vector Characterization of Liquid Using an Artificial Dielectric

A device for performing vector transmission spectroscopy on aqueous and polar solvent specimens at terahertz frequencies is presented. The device works on the principle of artificial dielectric birefringence by making a microfluidic grating in silicon. The device enables the direct measurement of the complex dielectric function of a liquid, across a wide terahertz band using a Fourier transform infrared spectrometer. Characterization data from a range of liquid specimens, including alcohol, acetone, hydrogen peroxide and whiskies are presented. Using microfluidic sampling, specimen handling is straightforward and direct measurements on strongly terahertz absorbing solvents are possible. The method is scalable to longer or shorter wavelengths.

Study on Lithium Niobate Wafer Bonding and Thinning

LN is a kind of pyroelectric material. It can be made into a sensitive layer belonging to photoelectric detector’s sensitive element. Usually, the thickness of LN wafer is 0.5mm and that is beyond the requirement for thickness of photoelectric sensitive element. Due to that, LN wafer must be disposed of by bonding, thinning and polishing process. The process mainly contain RZJ-304 photoresist bonding, grinding, polishing, stripping liquid stripping and acetone cleaning. After processed, the dimension of LN wafer is 10mm×10mm×50um. The surface of LN is very smooth, and the surface roughness is 1.63nm.The test shows that the disposed wafer’s peak value of pyroelectric signal is four times as much as that of undisposed one.

A Monte Carlo revisiting of N-methylformamide and acetone

The pure liquids N-methylformamide and acetone have been revisited via Monte Carlo simulations in the NTP ensemble at 1 atm and 25 °C. The molecules are all-atom rigid structures, and the intermolecular potential used is the classical 6-12 Lennard-Jones plus Coulomb. The theoretical g(r)s of both liquids were compared with those obtained from neutron diffraction and empirical potential structure refinement simulations. The results point to the existence of H-bonds driving the N-methylformamide structure, while in acetone the correlations are dipole moment oriented. The structure of the liquid N-methylformamide is mainly guided by a dimer whose molecules are arranged in such a way that the angle between their dipole moments is 73°, while liquid acetone is much less organized and the orientation of the molecules changes from an antiparallel dipolar correlation at short distances to more parallel alignments of the molecular dipole moments for larger distances.

Viscosity sensor using ZnO and AlN thin film bulk acoustic resonators with tilted polar c-axis orientations

We present a theoretical analysis of liquid viscosity sensors using ZnO and AlN thin film bulk acoustic wave resonators (FBARs) with tilted polar c-axis orientations. Besides the thickness longitudinal mode, the tilted c-axis orientation induces thickness shear mode in the resonator, which allows resonators operated in liquid medium without significant damping for sensory application. The equation for predicting electric impedance of shear mode film bulk acoustic wave resonators (FBARs) with a viscous liquid loading was derived from the basic piezoelectric constitutive equations. The viscosity sensitivity of shear mode ZnO and AlN resonators was achieved by calculation of resonant frequency shift due to viscous liquid loading. In the simulation, it is assumed that all the resonators have 2 μm thickness and 300 μm×300 μm electrode area; three different liquids (water, acetone, and olive oil) were chosen as the liquid loadings; and different tilt c-axis angles for both ZnO FBARs and AlN FBARs have been examined. It was found that the sensitivities of shear mode resonators to the three liquid loading are very close, and do not change much with the c-axis tilt angle with a value rang from 0.91e-3 to 0.97e-3 (kg m−3 Pa·S)−0.5 for ZnO FBARs and from 1.12e−3 to 1.13 e−3 (kg m−3 Pa·S)−0.5 for AlN FBARs. When the resonator’s mechanical quality factor (Q) is changed from 50 to 10 000, viscosity sensitivities are almost same. However, Q has a great effect on resonator impedance; and if Q is too low or the viscosity of the liquid is high, the maximum phase angle of the resonator will be less than 0, which makes excitation of the oscillation difficult if an oscillator circuit is used for sensor measurement. The results can be used for design and application of ZnO or AlN FBARs to monitor liquid viscosity.

Intramolecular soft modes and intermolecular interactions in liquid acetone

Resonant inelastic x-ray scattering spectra excited at the O1s(-1)pi* resonance of liquid acetone are presented. Scattering to the electronic ground state shows a resolved vibrational progression w ...

Transitions of morphological patterns of crystallizing polycarbonate in thin films

AbstractThis article reports the transitions of morphological patterns of polycarbonate crystals in thin films by solvent‐induced crystallization (SINC). As a substrate (silica glass) deposited with an amorphous and micron‐thick bisphenol A polycarbonate polymer film is partially dipped into a liquid acetone bath, acetone penetrated rapidly through the polymer film. The rate of acetone penetration is significantly higher than the predicted by Fickian diffusion or anomalous diffusion model, indicating that the capillary force through stress‐induced cracks may have played a major role in the upward transport of acetone through the polymer films. The morphologies of polycarbonate at different vertical positions on a substrate surface were analyzed by scanning electron microscopy and atomic force microscopy. It was observed that depending on the local acetone concentration the polymer morphologies showed quite diverse patterns ranging from stress‐induced cracks to fully developed three‐dimensional spherulites. The diverse morphologies developed during the thin film SINC may serve as a useful platform for further detailed mechanistic analysis of structures and crystallization kinetics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Molecular dynamics of liquid acetone determined by depolarized Rayleigh and low-frequency Raman scattering spectroscopy

Slow to ultrafast dynamics of liquid acetone at variable temperature was investigated by depolarized Rayleigh and low-frequency Raman scattering spectroscopy, in the region 0-200 cm(-1). A detailed analysis was performed on the spectra and corresponding time responses, and a consistent view of the molecular dynamics of this dipolar solvent was obtained. The effects of temperature on the spectra were interpreted, and distinct dynamical processes identified. At very low frequencies, or long time scales, acetone dynamics is characterized by a slow diffusive reorientation obeying the Stokes-Einstein-Debye hydrodynamic theory only in the limit of subslip boundary conditions. An alternative model based on the microviscosity concept proved to be able to reproduce this correlation time and its temperature dependence. A comparative analysis of collective and single-molecule reorientational times, these latter estimated from intramolecular Raman spectra, led to an orientational correlation parameter g(2) of unity, which denotes a statistical disorder of molecular polarizability tensors. A fast local restructuring process is putatively responsible for an additional contribution at subpicosecond time scales often referred to as intermediate response in other molecular liquids. The high frequency portion of the dynamical susceptibility showed the signature of librational intermolecular motions, giving rise to an ultrafast decay of the time correlation function of polarizability anisotropy. The overall approach, which provided valuable information on dynamics, structure and molecular interactions of neat acetone, will be applied to acetone electrolytic solutions.

Study of the isotropic to smectic-A phase transition in liquid crystal and acetone binary mixtures

The first-order transition from the isotropic (I) to smectic-A (Sm A) phase in the liquid crystal 4-cyano-4(')-decylbiphenyl (10CB) doped with the polar solvent acetone (ace) has been studied as a function of solvent concentration by high-resolution ac-calorimetry. Heating and cooling scans were performed for miscible 10CB+ace samples having acetone mole fractions from x(ace)=0.05 (1 wt %) to 0.36 (10%) over a wide temperature range from 310 to 327 K. Two distinct first-order phase transition features are observed in the mixture whereas there is only one transition (I-Sm A) in the pure 10CB for that particular temperature range. Both calorimetric features reproduce on repeated heating and cooling scans and evolve with increasing x(ace) with the high-temperature feature relatively stable in temperature but reduced in size while the low-temperature feature shifts dramatically to lower temperature and exhibits increased dispersion. The coexistence region increases for the low-temperature feature but remains fairly constant for the high-temperature feature as a function of x(ace). Polarizing optical microscopy supports the identification of a smectic phase below the high-temperature heat capacity signature indicating that the low-temperature feature represents an injected smectic-smectic phase transition. These effects may be the consequence of screening the intermolecular potential of the liquid crystals by the solvent that stabilizes a weak smectic phase intermediate of the isotropic and pure smectic-A.

Measurements of laminar flame speeds of acetone/methane/air mixtures

The effect of acetone on the laminar flame speed of methane/air mixtures is investigated over a range of stoichiometries at atmospheric pressure and room temperature. The liquid acetone is vaporised and seeded into the methane/air mixture at 5%, 9% and 20% of the total fuel by mole. The experiment is performed using the jet-wall stagnation flame configuration and the particle imaging velocimetry (PIV) technique. Laminar flame speeds are derived by extrapolating the reference flame speed back to zero strain rate. Experimental results are compared to numerically calculated values using a base methane chemical kinetic mechanism (GRI-Mech 3.0) extended with acetone oxidation and pyrolysis reactions from the literature. The experimental results show that acetone addition does not affect the laminar flame speed of methane significantly within the range of concentrations considered, with a stronger effect on the rich range than under fuel-lean conditions, and that the peak laminar flame speed of acetone in air is ∼42.5 cm/s at ϕ = 1.2. Simulation results reveal that the most important reactions determining acetone laminar flame speeds are H + O 2 → O + OH, OH + CO → H + CO 2, HO 2 + CH 3 → OH + CH 3O and H + O 2 + H 2O → HO 2 + H 2O. Comparison of the expected disappearance of acetone relative to methane shows that the former is a good fluorescent marker for the latter.

Development and Application of a Milli-Whistle for Use in Gas Chromatography Detection

A simple milli-whistle was developed for the use in GC (gas chromatography) detection, in which, compared to a thermal conductivity detector (TCD), 1 order of magnitude superior sensitivity can be obtained. The milli-whistle can be connected to the outlet of a GC capillary. The gas and makeup gas passing through the capillary produces a sound as it passes through the milli-whistle (i.e., the gas of the GC eluate). The sound can easily be detected by a microphone, which, after a Fourier transform (FT) by means of a LabVIEW (Laboratory Virtual Instrumentation Engineering Workbench) built-in program, a very sharp frequency peak (full width at half-maximum, approximately 1.6 Hz) can be simultaneously observed. As a result, GC elutes can be qualitatively determined on the basis of their retention times, and a quantitative analysis can be achieved on the basis of the frequency shifts. When the makeup and carrier gases used were nitrogen, in the case of gas samples, including hydrogen, helium, argon, and carbon dioxide, the limits of detection were found to be approximately 3 microL/each injection; in the case of liquid samples, including methanol, cyclohexane, tetrahydrofuran, hexane, and acetone, the limits of detection were determined to be approximately 10 microg/each injection, respectively. When the gases were changed to hydrogen, the limits of detection were dramatically improved. When acetone was selected as the model sample, a linear relationship was found in the range of 0.2-200 microg/injection.

Pressure-Induced Insertion of Liquid Acetone into the Graphite Oxide Structure

An expansion of the graphite oxide structure due to pressure-induced insertion of acetone solvent was observed upon compression at 0.9 GPa. However, conversion into the expanded high-pressure phase is not complete, with the high-pressure and the ambient-pressure phases coexisting even at pressures up to 4.5 GPa. The phase transformation is not correlated with the solidification point of acetone, a behavior similar to that of the graphite oxide/alcohol systems and unlike that of the previously studied graphite oxide/water system. It can be concluded that pressure-induced insertion of solvent into the graphite oxide structure occurs not only for protic solvents (water, methanol, ethanol) but also for aprotic polar solvents (acetone).

Capillary Negative Pressure Measured by Nanochannel Collapse

A new method is presented to measure capillarity-induced negative pressure. Negative pressures of several bars have been measured for five different liquids (ethanol, acetone, cyclohexane, aniline, and water) over a range of surface tension. Capillary negative pressure was measured in 79 +/- 3 nm silica nanochannels on the basis of the determination of the critical channel width for elastocapillary collapse of the flexible plate covering the channels. The results are consistent with the Young-Laplace equation.

Interactions of phase equilibria, jet fluid dynamics and mass transfer during supercritical antisolvent micronization

Supercritical antisolvent (SAS) precipitation has been successfully used in the micronization of several compounds. Nevertheless, the role of high-pressure vapor–liquid equilibria, jet fluid dynamics and mass transfer in determining particle size and morphology is still debated. In this work, CO 2 has been adopted as supercritical antisolvent and elastic light has been used to acquire information on jet fluid dynamics using thin wall injectors for the investigation of the liquid solvents acetone and DMSO at operating conditions of 40 °C in the pressure range between 6 and 16 MPa. The results show that two-phase mixing after jet break-up is the phenomenon that characterizes the jet fluid dynamics at subcritical conditions. When SAS is performed at supercritical conditions a transition between multi-phase and single-phase mixing is observed by increasing the operating pressure. Single-phase mixing is due to the very fast disappearance of the interfacial tension between the liquid solvent and the fluid phase in the precipitator. The transition between these two phenomena depends on the operating pressure, but also on the viscosity and the surface tension of the solvent. Indeed, single-phase mixing has been observed for acetone very near the mixture critical point, whereas DMSO showed a progressive transition for pressures of about 12 MPa. In the second part of the work, a solute was added to DMSO to study the morphology of the microparticles formed during SAS precipitation at the different process conditions, to find a correlation between particle morphology and the observed jet. Expanded microparticles were obtained working at subcritical conditions; whereas spherical microparticles were obtained operating at supercritical conditions up to the pressure where the transition between multi- and single-phase mixing was observed. Nanoparticles were obtained operating far above the mixture critical pressure. The observed particle morphologies have been explained considering the interplay among high-pressure phase equilibria, fluid dynamics and mass transfer during the precipitation process.

Sensing properties of CdS-doped tin oxide thick film gas sensor

The tin oxide (SnO 2) thick film gas sensor is fabricated by employing screen-printing technology. This pure SnO 2 thick film is doped with 1 or 2 wt% of cadmium sulphide (CdS) by its weight and, thereby, the effect of dopant is presented. X-ray diffraction (XRD) analyses are administrated, which suggest that CdS dopant inhibits the crystallite growth leading to nanometric reduction in grain size. The fabricated gas sensor is responsively studied on exposure to liquid petroleum gas (LPG), methanol, and acetone. It is observed that CdS (2 wt%) doped structure exhibited highest response and is more selective to methanol (70 for 5000 ppm) over LPG and acetone at the operating temperature 200 °C. The CdS-doping improved response- and recovery-time from 90 s and 200 s, for undoped-film, to 40 s and 110 s for methanol (5000 ppm at 200 °C).