Transparent Drop Research Articles

Reversible Electrochromic/Electrofluorochromic Dual Switching in Zn(II)-Based Metallo-Supramolecular Polymer Films.

The introduction of novel materials with multifunctional chromogenic properties, such as electrochromic/electrofluorochromic (EC/EFC) properties, has recently attracted prospective interest in the development of various optoelectronic devices and smart windows. In this study, a novel Zn(II)-based metallo-supramolecular polymer (polyZn) has been developed as an ON/OFF switchable EFC application with prominent EC behavior. In this regard, the polymeric chain of polyZn was first synthesized by 1:1 complexation in a zigzag manner with Zn(II) ions at the metal center and 4,4'-[bis(2,2':6',2″-terpyridinyl)benzene]triphenylamine (LTPY-TPA) as the redox-active ditopic ligand. The polyZn exhibits excellent solubility in organic solvents and can form a very good uniform thin film on an indium tin oxide/glass substrate by spin-coating. In a neutral state, transparent polyZn exhibits a bright yellow color to the naked eye (absorption at ∼325 nm). The electroactive triphenylamine (TPA) core of LTPA-TPY, however, undergoes reversible single-electron oxidation when a positive bias of +1.6 V vs Ag/Ag+ is applied, generating radical cations (TPA ↔ TPA•+) with a significant drop in transparency (77%). A noticeable chromic shift in the hue of the film from brilliant yellow to green was observed with the appearance of a near-infrared absorption band at ∼897 nm with a tail of 1300-1600 nm. Interestingly, in addition to this EC phenomenon, the fabricated solid-state polyZn film exhibits intense, high-contrast reddish-orange photoluminescence with λem = 650 nm, which is significantly desired as a molecular probe for bioimaging. Both the TPA core and the redox-inactive Zn(II)-terpyridine core emit orange-red photoluminescence in polyZn, which is significantly quenched upon the oxidation of the film and is re-emitted at 0.0 V vs Ag/Ag+. This ON/OFF EFC transition was sustained for several cycles. This study should motivate to design and create distinctive new unique materials with combined EC/EFC behavior for the fabrication of optoelectronic devices by combining a metal-fluorescent core with a redox-active spacer.

Ballad

Ballad MICHALIS GANAS (Translated by Avi Sharon) Days come where I forget my name. Rain-soaked nights come cotton fogs the flour becomes grain then cornstalk peak July with countless scythes whispers in the middle of winter. I see the fabric of the world unravel the hand that untwines it invisible and I shudder if the thread were cut. Thread of water warp without memory transparent drop on moss and lichen snow-down on the mountains leaf-lashing hail and suddenly a warm dive suit in the ark of the womb. Archaic night melts and groans the flame that licks it immaculate. Congregations of waters downpours ancestors glaciers still in the hoarfrost of anonymity. arion 29.1 spring/summer 2021 64 ballad Days come where I forget my name. Mineral nights arrive loose-combed memory founders and reappears volcanic and black with grass-blades from the meadow acorns shells a dim and distant light—drizzle of nostalgia. And I leave for other eras. Laden with bodies. Years arrive snows that scald me blood that gallops and a full-moon glance from the opposite shore. A villager tall honest—one of the sorrowful— with a woman halo of thorns on his head and love untold in his breast. And I prophesy the past words never before spoken and I say Michalis Ganas 65 Every time I saw you you were farther away. And more foreign. Wife of my brother already pregnant with Andreas and me just fourteen. You held a cracked jar that night in the cellar shining a candle for me. What a difficult transfusion as if it were blood and not wine and we with our four hands eyes that avoid each other and if they cheat regret it fixed upon the coursing flow the thread of drunkenness that bound us like a birth-cord changing the bread and wine of our bodies in holy communion. 66 ballad Was I listening or speaking? Fertile sorrow inside me ripened to a starry blur bounteous as a summer harvest and deeper still the black grass which requires two for pasture was undulating raw sodden and bitter before it reached our eyes and hurled us into the white dark. Michalis Ganas 67 I gaze into a well. It stares back. We stare at each other for a long time like contrary siblings. One-eyed darkness lures me on and I descend stone by stone a vertiginous painting. Sotiri. It’s your fingers that hold me it’s my own body at risk I slip and you call out to me: “Constantine.” My curly hair is falling out and my yellow moustache like a sick child I whisper my evening prayer 68 ballad A mother I did seek to find at her side daggers nine and her only daughter. I find her among the basil leaves amid five horrific dreams and in the wayside cloveroot. If a downpour now would only break to startle Konstantis awake and send him homeward sopping. Let him have dry clothes to wear and quietly reproach him there . . . Michalis Ganas 69 Mother—it’s not the mountains. It’s their shadow that steps on me. Nor is it the cypresses. It’s the slithering grass. Crashing down upon me. It’s a golden bee from the world above. She finds me in the flowers and turns me into wax—not honey. That I may be her venom. I will burn in a country chapel melting the meager darkness before the oily fingers of the sacristan can blot me out. In this way mother they choke the flame without blowing lest the souls catch fire and set all the underworld ablaze. Profound dawn. He bends down to gather water and enters the tomb again through the cypress tree. Bee-swarm of birds. 70 ballad Night of the Cimmerians. Abrupt descent and I follow blindly the black ram. No branch or root to grab onto my bones creaking. The air carries here and there the scent of dry laurel and a scarf like a bat’s wing startles me. This is no place for children—what am I looking for with my short pants and shaved head calling out for...

Surface-Segregation-Induced Nanopapillae on FDTS-Blended PDMS Film and Implications in Wettability, Adhesion, and Friction Behaviors.

Polymer composites have been extensively used to tune the surface property (e.g., wettability, friction, and adhesion) for its advantages of cost-effectiveness, high efficiency, and ease of fabrication. In this work, different amount of trichloro(1H,1H,2H,2H-perfluorooctyl)silane (FDTS) was added into poly(dimethylsiloxane) elastomer to prepare polymer composite films and were selected as a model to illustrate the effects of surface segregation on surface topology, wettability, friction, and adhesion. The results show that the added FDTS forms aggregations and increasing the content of FDTS leads to the difficulty of air bubble elimination, increase in viscosity, and drop in transparency. Driven by the differences of chemical potential, FDTS aggregations migrate to the air-polymer interface, resulting in surface enrichment and formation of nanopapillae (1-200 nm). This phenomenon becomes more significant with the increment in FDTS. The change in surface composition and structure generates profound effects on wettability, friction, and adhesion. The addition of FDTS makes the surface relatively oleophobic and further increasing the content of FDTS does not helpful in improving the oleophobicity due to the notable aggregation. Friction forces first grow with the increasing content of FDTS and then decline after the maximum point at 1.0 wt % of FDTS, which is attributed to the generated regular larger nanopappillae at high concentration. However, these larger nanopapillae lead to the increase in adhesion because more interactions are formed. The findings demonstrate the behaviors of FDTS in polymer composites and provide important guidance for controlling the formation of nanostructures via aggregation and phase segregation and exploring their implications on surface properties.

A Non‐Exploding Alkali Metal Drop on Water: From Blue Solvated Electrons to Bursting Molten Hydroxide

AbstractAlkali metals in water are always at the brink of explosion. Herein, we show that this vigorous reaction can be kept in a non‐exploding regime, revealing a fascinating richness of hitherto unexplored chemical processes. A combination of high‐speed camera imaging and visible/near‐infrared/infrared spectroscopy allowed us to catch and characterize the system at each stage of the reaction. After gently placing a drop of a sodium/potassium alloy on water under an inert atmosphere, the production of solvated electrons became so strong that their characteristic blue color could be observed with the naked eye. The exoergic reaction leading to the formation of hydrogen and hydroxide eventually heated the alkali metal drop such that it became glowing red, and part of the metal evaporated. As a result of the reaction, a perfectly transparent drop consisting of molten hydroxide was temporarily stabilized on water through the Leidenfrost effect, bursting spectacularly after it had cooled sufficiently.

A Non-Exploding Alkali Metal Drop on Water: From Blue Solvated Electrons to Bursting Molten Hydroxide.

Alkali metals in water are always at the brink of explosion. Herein, we show that this vigorous reaction can be kept in a non-exploding regime, revealing a fascinating richness of hitherto unexplored chemical processes. A combination of high-speed camera imaging and visible/near-infrared/infrared spectroscopy allowed us to catch and characterize the system at each stage of the reaction. After gently placing a drop of a sodium/potassium alloy on water under an inert atmosphere, the production of solvated electrons became so strong that their characteristic blue color could be observed with the naked eye. The exoergic reaction leading to the formation of hydrogen and hydroxide eventually heated the alkali metal drop such that it became glowing red, and part of the metal evaporated. As a result of the reaction, a perfectly transparent drop consisting of molten hydroxide was temporarily stabilized on water through the Leidenfrost effect, bursting spectacularly after it had cooled sufficiently.

Light scattering and transmission studies of nanofiller particulate size, matrix cavitation, and high strain interfacial dewetting behavior in silica‐elastomer composites

AbstractThe effect of silica nanofiller surface chemistry on compounded particle size and high strain particle dewetting in a semitransparent nanosilica‐filled elastomer composite was determined using backscattered visible light and transmitted light, respectively. The integrated intensities of backscattered light from the samples were collected at various visible wavelengths for thin‐film composites using ultraviolet–visible spectrometer with an integrating sphere. The data revealed strong Rayleigh‐type scattering from compounded filler particles. Size information was extracted and found to broadly correlate with scanning electron microscopy image analysis of fracture surface. Incorporation of a siloxane surface treatment chemical during compounding resulted in a reduced average filler particle size in the cured composite. On extension of the samples, an optical transition was observed only in the filled composites. At high strains, the semi transparent samples displayed an abrupt drop in transparency becoming opaque. This was quantified using a simple light transmission‐sample extension technique. Strain‐induced crystallization was discounted as the cause for the transition by X‐ray diffraction analysis. The onset yield stress for the optical transition was found to be filler surface‐chemistry‐dependent with the siloxane‐treated filler exhibiting a greatly increased onset stress value. These observations were discussed and rationalized in terms of filler particle–matrix dewetting and cavitation at high strains. Matrix–filler dewetting was distinguished from matrix cavitation by comparison with Beer–Lambert behavior derived from unstrained samples. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011.

Development of the technology of contacting ZnSe infrared optical windows using polyethylene films

We present a novel technology intended for contacting ZnSe IR optical windows. Thin polyethylene films located between plates made of ZnSe are irradiated by strong IR radiation produced by a CO2 laser. The IR radiation caused changes in the structure of the polymer, which result in the high adhesion of polymer to the surfaces of ZnSe elements to be contacted. The technology enables contacting that maintains transparency in the broad IR band (1 to 25 ?m) except for a few narrow absorption bands. Low wavefront distortion is established by a thorough interferometry study of contacted elements. The contacted ZnSe elements allow 100 W of CO2 laser radiation to pass for 1 h with no drop in transparency. Special tests prove the high thermal stability of the bonded elements. The technology is intended for a wide range of IR optics applications.

Variable focal lens controlled by an external voltage: An application of electrowetting

We use electrocapillarity in order to change the contact angle of a transparent drop, thus realizing a lens of variable focal length (B. Berge, J. Peseux, Patent deposited in Grenoble France, October 8th 1997, numero d'enregistrement national 97 12781). The key point is the application of gradients of wettability, which control the shape of the drop edge, in our case a centered circle of variable radius. The quality and reversibility of the lens are surprisingly good. The optical power variation can be 5 to 10 times the one of the human eye, for a comparable diameter, with a typical response time of 0.03 s and a dissipated power of a few mW.

Liquid laser cavities and waveguides. III. Radiation coupling-out and fluorescence under uniform excitation. 'Evapolators'

An investigation was made of laser radiation coupling-out from totally reflecting closed liquid cavities by local frustration of total internal reflection with the aid of internal water spheres and external contact with a substrate or a prism. A rotating drop of ethanol containing rhodamine B in an envelope of liquid C8F18 generated laser radiation with a divergence of several angular degrees and an efficiency up to 5% relative to the excitation energy. A transparent drop of ethanol with rhodamine B, suspended in air, and subjected to uniform pumping was used to determine the depth of the zone in which lasing took place in a liquid cavity. An increase in the integral (during the pump time) fluorescence energy from a selected internal part of this drop, which did not participate in lasing, on increase in the excitation flux was in agreement with the expectations and it began to fall at high pump intensities. Characteristics of oscillations in immiscible liquids which evaporated in an evaporator — oscillator ('evapolator') were discussed.

Stability of small vibrations of a transparent drop in a high-power optical field

The influence of ponderomotive forces on the stability of small vibrations of a transparent drop subjected to a high-power optical field is considered theoretically. The condition for the instability of the vibrations is derived for a low-viscosity liquid. The expression for the threshold incident radiation intensity, above which small vibrations of a drop become unstable, is obtained on the assumption of a Rayleigh distribution of the electromagnetic field inside the drop. Numerical estimates of the instability threshold are obtained for water drops.

Deformation and stability of a transparent drop in an intense light field

Deformation and stability of a transparent drop in an intense light field