Yazarlar bu teknik için ilk fikir yardım için James A. Forrest kabul etmek istiyorum. 26 Bu çalışma Pennsylvania Üniversitesi fon tarafından desteklenen ve kısmen hiçbir ödül altında Ulusal Bilim Vakfı MRSEC programı tarafından desteklenmiştir. DMR-11- Pennsylvania Üniversitesi&#39;nde 20.901.

1. Film hazırlanması <ol><li> Polistiren 0.04 g tartılır ve bir 30 ml şişe içine yerleştirin. </li><li> Şişe içine tolüen 2 g tartılır. Toluen içinde polistirenin ağırlık çözeltisi bir% 2, yaklaşık 100 nm&#39;lik bir filmi elde edilir. </li><li> Çözelti oturmak O / N tamamen polistiren çözülür ve çözümleri yerleşmek izin edelim. </li><li> Bir Spin Coater üzerine 1 cm x 1 cm Silikon (Si) gofret yerleştirin. </li><li> 45 saniye boyunca 8000 rpm&#39;de gofret dönerler. Bu eğirme olsa da, iplik gofret tolüen yaklaşık 1 ml bırakın. Not: sıkma kaplama içeren tüm basamaklar, bir çeker ocak içinde gerçekleştirilir. </li><li> Si gofret tüm yüzeyi kaplıdır kadar artık sabit Si gofret, Si gofret üzerine 1.3 damla damla adımından çözüm ekleyin. </li><li> Çözüm gofret üzerinde kurumadan önce, 20 saniye boyunca 4000 rpm&#39;de Si gofret dönerler. </li><li> Elipsometri kullanarak filminin kalınlığını belirleyin (bkz: adım 2). </li><li> Film kalınlığı, istenen, Ann ise15 saat süre ile 393 K bir vakumlu fırın içinde filmi eal. </li></ol> 2. Film Kalınlığı Belirlenmesi <ol><li> Elipsometre sahneye döndü dökme filmi yerleştirin ve 1 sn edinimi zaman ve bölge ortalama ayarı ile 70 ° lik bir olay ışık açıyla Elipsometrik açıları Ψ (λ) ve Δ (λ) açık ölçün. </li><li> Elipsometre yazılımı kullanılarak, imalatçının protokolüne göre bir üç tabakalı model için elde edilen Ψ (λ) ve Δ (λ) veri uygun. Hiçbir ek kullanıcı girişi vardır. Birinci tabaka bir Si alt-tabaka bir tabakadır (n = A B / λ 2, k = 0 +), burada karşılık gelen ikinci tabaka 1,5 nm kalınlığında bir nativ oksit tabakası ve üçüncü tabaka, bir Cauchy modelidir polistiren filmin optik özellikleri. Bu modelde, A ve B, uygun parametrelerdir ve n ve k, sırasıyla kırılma indeksinin gerçek ve hayali bileşenleridir. </li><li> Cauchy katmanı için t sığacakhickness ve A ve B parametreleri filmin 10 nm üzerinde ise. Film 10 nm altında ise, sadece A uyacak. Not: Bu Temsilcisi sonuçları bölümünde daha ayrıntılı olarak ele alınacaktır. </li></ol> 3. Soğutma Hızı Bağımlı T g Ölçümleri <ol><li> Coat termal macun ile değişken sıcaklık elipsometre aşamasında ısıtma elemanının yüzeyi. </li><li> Isıtma elemanının üzerine tavlanmış polistiren filmi yerleştirin. </li><li> Isıtma elemanı sıkıca filmi kelepçe. </li><li> &lt;69 KPa civarında bir basınç altında ısı aşamasında% 100 kuru azot gazı akış. </li><li> Sıcaklık sahne yazılımı kullanarak, bir sıcaklık profili oluşturmak. Bu sıcaklık profili 150 K / dakika ile 393 K bir ısıtma rampası ile başlar. 20 dakika boyunca 393K Filmi tutun. <ol><li> Daha sonra, oranlarında 293 K alternatif soğutma rampaları 150, 120, 90, 60, 30, 10, 7, 150 K / dakika ile 393 K kadar ısıtma rampaları ile 3 ve 1 K / min. 5 dk tempe yerleştirinHer rampadan sonra rature tutun. </li></ol></li><li> Elipsometre yazılımında, alt-tabaka bir sıcaklığa bağlı Si modeline değiştirilir dışında Her üç tabaka da aynı olan bölüm 2&#39;de edilene sıcaklığa bağlı elipsometri modeli içindeki olun. </li><li> Sıcaklığa bağlı Si modeli için katmanında, Parametre &quot;Parm Giriş kullan Ext Temp&quot; açın. </li><li> Laboratuar ekipmanları kontrol yazılımı kullanarak, elipsometre yazılım sıcaklık aşamasından sıcaklık değerlerini okudum. </li><li> Sinyal maksimum yoğunluğa ulaşır şekilde elipsometre hizalayın. </li><li> &quot;Edit Donanım Yapılandırmaları&quot; altında, yüksek doğruluk bölge ortalama ile 1 sn hızlı toplama zamanı ayarlayın. Yüksek doğruluk bölge ortalama ile 3 saniye normal alım saatini ayarlayın. </li><li> Elipsometre yazılımında &quot;in situ&quot; sekmesi altında &quot;hızlı kazanım süresi modu&quot; kutusu ve basın &quot;Başlat Toplama&quot; kontrol edin. Ardından, başlangıçsıcaklık profili. 3 K / dak soğutma rampa önce hızlı kazanım süresi kutusunun işaretini kaldırın. </li></ol> 4. T g Değerlerini Belirleme <ol><li> Tercih grafik ve analiz yazılımı içine sıcaklık ve kalınlık profilleri İhracat ve 9 soğutma oranları için sıcaklık ve kalınlık verileri ayırın. </li><li> , Sıcaklığa satın alma sırasında bölge ortalamanın etkisi hesaba her sıcaklık değerini alır ve T = / 2, burada T i (T i-1 T +), öyle ki, ondan önceki sıcaklık değerine ile ortalama amacıyla bir sıcaklık belirli bir zamanda bir değer, ve T, i-1, önceki zaman noktasında sıcaklığıdır. </li><li> Her soğutma hızı için Sıcaklık karşı Plot Kalınlığı. </li><li> Süper Soğutmalı Sıvı rejimin bir kısmı üzerinde bir doğrusallaştırma (büyük genleşme katsayısı, yüksek sıcaklık rejimi) uygulayın. Bu rejim 393 K 380 K yaklaşık olacaktır </li><li> Perfoveri aynı setin, camsı rejiminin bir kısmı üzerinde doğrusal bir uyum rm. Bu rejim daha düşük bir genleşme katsayısına sahiptir ve 293 K 340 yaklaşık K. olacak </li><li> Bu iki satır kesişim noktasını bulun. Bu çizgilerin kesiştiği sıcaklığı, cam geçiş sıcaklığıdır. </li><li> Tüm dokuz rampalar için bunu yapın. </li></ol> 5. Ortalama İnce Film Dynamics Analizi <ol><li> Belirli bir film kalınlığı arsa Log (soğutma oranı (K / dakika)) karşı 1 / T g (K-1) için. </li><li> Ampirik ilişki ile toplu ve yüzey dinamiklerinin ölçümleri doğrudan dolaylı olarak bu karşılaştırın: Soğutma Hızı * τ α = 1000. 23,24 </li></ol>

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The Authors have no conflicts of interest to disclose.

Soğutma-Puan bağlı T g ölçümleri T g, cam ve süper soğutulmuş sıvı, ortalama dinamikleri sıcaklık bağımlılığı genleşme katsayısı ve belirli bir camsı malzemenin kırılganlığı belirleyebilir yüksek verimli karakterizasyon deneyleri vardır Tek deney. Onlar fluorophores veya diğer karmaşık deneysel teknikleri kullanmak yok çünkü Ayrıca, floresan, gömme veya nanohole gevşeme deneyleri aksine, CR-T g deneyleri nispeten hızlı ve basittir. Nedeniyle Elips...

Keddie Jones ve Corey 1 açıcı çalışmaları ultra-ince polistiren film cam geçiş sıcaklığı (Tg) 60 nm&#39;den daha düşük bir kalınlıkta kütle değerine göre düşürdüğü gösterilmiştir. O zamandan beri, birçok deneysel çalışmalar 2-11 T g gözlenen düşüşler bu filmlerin ücretsiz yüzeyine yakın gelişmiş hareketlilik tabakası neden olduğu hipotezini desteklemiştir. Ancak, bu deneyler, tek bir gevşeme zamanı dolaylı önlemler ve dolayısıyla ortalama ince film dinamikleri ve hava / polimer arayüzünde dinamikleri arasında doğrudan bir korelasyon merkezli bir tartışma 12- 18 var. Bu tartışmayı cevaplamak için birçok çalışma doğrudan serbest yüzey (τ yüzeyinin) dinamiklerini ölçüldü. Nanoparçacık gömme, 19,20 nanohole gevşeme, 21 ve floresan 22 çalışma gösteriyor ki, hava / polimer arayüzü hDaha hızlı τ a göre daha çok daha zayıf sıcaklık bağımlılığı ile toplu alfa gevşeme zamanı (τ α) &#39;den büyüklük dinamikleri emirleri gibi. Çünkü zayıf sıcaklık bağımlılığının, bu filmlerin τ yüzeyi, ince polistiren filmlerin 19-22 ve gelişmiş dinamikleri, 23,24 yukarıdaki birkaç derece tek bir nokta T *, at (τ α) toplu alfa gevşeme kesişiyor T g ve ≈ 1 sn τ a at. Hızlı * daha gevşeme süreleri prob deneyleri ultra-ince Polistiren filmlerin T g herhangi bir kalınlıkta bağımlılığı göremiyorum neden T * varlığı açıklayabilir. 13-18 Son olarak, ederken sahip olduğu gelişmiş mobil katman gösterisi doğrudan ölçümleri 4-8 nm kalınlığında, 20-22 hava / polimer arayüzünde dinamiklerinin yayılım uzunluğu mobil yüzey laye kalınlığından daha büyük olması kanıtlar vardırr. 5,25,26 Bu rapor tamamen oran bağımlı T g (CR-T g) deneyleri soğutma Elipsometri kullanmak için bir protokol açıklamayı amaçlamaktadır. CR-T g daha önce polistiren ultra-ince filmlerin ortalama dinamiklerini tanımlamak için kullanılmıştır. 23,24,27,28 Dahası, Bu teknik son zamanlarda kullanılan ultra-ince polistiren filmlerde ortalama dinamikleri arasında doğrudan bir ilişki göstermek için serbest yüzeyde ve dinamiği. 23 örneğin floresan, nanopartikül gömme, nanohole gevşeme, nanocalorimetry dielektrik spektroskopisi ve Brillouin ışık saçılması gibi ölçümler diğer tipleri üstüne CR-T g ölçümleri avantajı, araştırmalar, bunların nispeten hızlı olmasıdır ve basit deneyler florofor ya da diğer karmaşık deneysel teknikleri kullanmak kalmamasıdır. Spektroskopik Elipsometri son gelişmeler, teknik, etkili bir şekilde, optik Bu propert belirlemek için kullanılabilir izinpolimerler ve olağanüstü bir doğrulukla hibrid malzemelerin diğer türleri, ultra ince filmlerin ler. Bunun gibi, bu tekniğin cam geçiş (T ≤ T g, τ α ≥ 100 sn) ile ilgili sıcaklık ve zaman rejimlerde teknolojik uygulanabilir ince filmlerin ortalama dinamiklerini araştırıyor. Ayrıca, bu teknik camsı genişleme katsayıları hakkında bilgi verecek ve akşam yemeği sıvı devletlerin yanı sıra daha sonra toplu filmler için verileri ile mukayese edilebilir sistemin kırılganlığını soğutmalı. Son olarak, CR Tg deneyleri bu kadar uzun bir film bütünlüğü deney boyunca kalacak şekilde herhani bir cam sistemleri için de kullanılabilir.

<table><tbody><tr><td>Toluene</td><td>Sigma Aldrich</td><td>179418-1L</td><td>This can be purchased from any chemical company.</td></tr><tr><td>Atactic Polystyrene</td><td>Polymer Source Inc.</td><td>P-4092-S</td><td>This can be purchased from any chemical company.</td></tr><tr><td>THMS 600 temperature stage</td><td>Linkam</td><td>THMS 600</td><td>any temperature stage that can be fit to an ellipsometer could be used.</td></tr><tr><td>M2000V Spectroscopic Ellipsometer</td><td>J.A. Woollam</td><td>M200V</td><td>This procedure should be applicable for any spectroscopic ellipsometer.</td></tr><tr><td>Spin Coater</td><td>Laurell Technologies</td><td>WS-650-23B</td><td>This Procedure is possible with any spin coater</td></tr><tr><td>Sample vials</td><td>Fisher Scientific</td><td>02-912-379</td><td>Any sample vials will do</td></tr><tr><td>Silicon wafers</td><td>Virginia semi conductors</td><td>325S1410694D</td><td></td></tr></tbody></table>

cooling rate dependent ellipsometry measurements to determine the dynamics of thin glassy films

Bu rapor tamamen oran bağımlı T g (CR-T g) deneyleri soğutma Elipsometri kullanarak deneysel tekniğini anlatmak amaçlamaktadır. Bu ölçümler cam geçiş sıcaklığı belirleyebilir basit yüksek verimlilik karakterizasyon deneyleri vardır (T g), orta dinamiği, kırılganlık ve camsı malzemelerin çeşitli süper-soğutulmuş sıvı ve camsı durumlarının genleşme katsayısı. Bu teknik, diğer yöntemler, bu özelliklerin tümünü araştırmak için, farklı çeşitli teknikler kombine gerekir iken, bu parametreler, tek bir deneyde ölçülecek sağlar. Dinamikleri Ölçümler T g yakın özellikle zorlu. Şirketinden toplu ve yüzey gevşeme dinamikleri prob diğer yöntemlere göre oranına bağlı Tg ölçümleri soğutma avantajı, florofor ve daha diğer karmaşık ex kullanmayan için nispeten hızlı ve basit deneyler olmasıdırdeneysel bir teknikleri. Ayrıca, bu teknik cam geçiş (τ α&gt; 100 sn) ile ilgili sıcaklık ve gevşeme zamanında teknolojik ilgili ince filmler (τ α) rejimler ortalama dinamiklerini araştırıyor. Oranı bağımlı T g deneyleri soğutmak için Elipsometri kullanarak sınırlama (τ α &lt;&lt; 1 sn) o viskozite ölçümleri gevşeme süreleri ile ilgili soruşturma edemezler. Diğer soğutma oranı bağlı T g ölçüm teknikleri, ancak, daha hızlı gevşeme sürelerine CR-T g yöntemi uzanabilir. Ayrıca, bu tekniğin bu kadar uzun bir film bütünlüğü deney boyunca kalacak şekilde herhani bir cam sistemleri için de kullanılabilir.

Montaj Ham Elipsometri Veri Polistiren filmler Elipsometre (500-1,600 nm) dalga boyu aralığında saydamdır. Böylece Cauchy modeli polistiren filmler kırılma endeksi tarif etmek için iyi bir modeldir. Şekil 1A polistiren kalın (274 nm) film ve elde edilen oturması için Ψ (λ) ve ö (λ) bir örneğini göstermektedir Cauchy modeli <img alt="Denklem 1" src="/files/ftp_upload/53499/53...

Watch this Scientific Journal Video about Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films at JoVE.com

Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films

Burada, cam malzemelerin çeşitli oranı cam geçiş sıcaklığı (Tg) belirleyebilir bağımlı elipsometri deneyleri, ortalama dinamikleri, kırılganlık ve süper-soğutulmuş sıvı genleşme katsayısına ve cam soğutmak için bir protokol mevcut.

Puan Bağımlı Elipsometri Ölçümleri Soğutma İnce Camsı Filmlerin dinamikleri belirleme

This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements ...

cooling-rate-dependent-ellipsometry-measurements-to-determine

Universidad de Cartagena UDEC

Research

JoVE Journal

Chemistry

8.1K Görüntüleme.  University of Pennsylvania.  Burada, cam malzemelerin çeşitli oranı cam geçiş sıcaklığı (Tg) belirleyebilir bağımlı elipsometri deneyleri, ortalama dinamikleri, kırılganlık ve süper-soğutulmuş sıvı genleşme katsayısına ve cam soğutmak için bir protokol mevcut. 

Video: Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films

High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings

Micro-electronic devices often undergo significant self-heating when biased to their typical operating conditions. This paper describes a convenient optical micro-imaging technique which can be used to map and quantify such behavior. Europium thenoyltrifluoroacetonate (EuTFC) has a 612 nm luminescence line whose activation efficiency drops strongly with increasing temperature, due to T-dependent interactions between the Eu3+ ion and the organic chelating compound. This material may be readily coated on to a sample surface by thermal sublimation in vacuum. When the coating is excited with ultraviolet light (337 nm) an optical micro-image of the 612 nm luminescent response can be converted directly into a map of the sample surface temperature. This technique offers spatial resolution limited only by the microscope optics (about 1 micron) and time resolution limited by the speed of the camera employed. It offers the additional advantages of only requiring comparatively simple and non-specialized equipment, and giving a quantitative probe of sample temperature.

Europium thenoyltrifluoroacetonate (EuTFC) has an optical luminescence line at 612 nm, whose activation efficiency decreases strongly with temperature. If a sample coated with a thin film of this material is micro-imaged, the 612 nm luminescent response intensity may be converted into a direct map of sample surface temperature.

Öropiyum Şelat Lüminesans Kaplamaları Kullanma yüksek çözünürlüklü Termal Mikro görüntüleme

Micro-electronic devices often undergo significant self-heating when biased to their typical operating conditions. This paper describes a convenient ...

Mühendislik

Evanescent Field Based Photoacoustics: Optical Property Evaluation at Surfaces

Here, we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. Optical property evaluation of thin films and the surfaces of bulk materials is an important step in understanding new optical material systems and their applications. The method presented can estimate thickness, refractive index, and use absorptive properties of materials for detection. This metrology system uses evanescent field-based photoacoustics (EFPA), a field of research based upon the interaction of an evanescent field with the photoacoustic effect. This interaction and its resulting family of techniques allow the technique to probe optical properties within a few hundred nanometers of the sample surface. This optical near field allows for the highly accurate estimation of material properties on the same scale as the field itself such as refractive index and film thickness. With the use of EFPA and its sub techniques such as total internal reflection photoacoustic spectroscopy (TIRPAS) and optical tunneling photoacoustic spectroscopy (OTPAS), it is possible to evaluate a material at the nanoscale in a consolidated instrument without the need for many instruments and experiments that may be cost prohibitive.

Here we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. This technique evanescent field-based photoacoustics can be used to create a photoacoustic metrology system to estimate materials&#39; thicknesses, bulk and thin film refractive indices, and explore their optical properties.

Evanescent Alan Bazlı photoacoustics: Optik Mülkiyet Değerlendirme Yüzeylerde

Here, we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. ...

Electrospray Deposition of Uniform Thickness Ge23Sb7S70 and As40S60 Chalcogenide Glass Films

Solution-based electrospray film deposition, which is compatible with continuous, roll-to-roll processing, is applied to chalcogenide glasses. Two chalcogenide compositions are demonstrated: Ge23Sb7S70 and As40S60, which have both been studied extensively for planar mid-infrared (mid-IR) microphotonic devices. In this approach, uniform thickness films are fabricated through the use of computer numerical controlled (CNC) motion. Chalcogenide glass (ChG) is written over the substrate by a single nozzle along a serpentine path. Films were subjected to a series of heat treatments between 100 &#176;C and 200 &#176;C under vacuum to drive off residual solvent and densify the films. Based on transmission Fourier transform infrared (FTIR) spectroscopy and surface roughness measurements, both compositions were found to be suitable for the fabrication of planar devices operating in the mid-IR region. Residual solvent removal was found to be much quicker for the As40S60 film as compared to Ge23Sb7S70. Based on the advantages of electrospray, direct printing of a gradient refractive index (GRIN) mid-IR transparent coating is envisioned, given the difference in refractive index of the two compositions in this study.

Electrospray Deposition of Uniform Thickness Ge23Sb7S70 and As40S60 Chalcogenide Glass Films

A method of uniform thickness solution-derived chalcogenide glass film deposition is demonstrated using computer numerical controlled motion of a single-nozzle electrospray.

Düzgün kalınlığı Ge Elektro Biriktirme<sub&gt; 23</sub&gt; Sb<sub&gt; 7</sub&gt; S<sub&gt; 70</sub&gt; Ve de<sub&gt; 40</sub&gt; S<sub&gt; 60</sub&gt; Chalcogenide Cam Filmleri

Solution-based electrospray film deposition, which is compatible with continuous, roll-to-roll processing, is applied to chalcogenide glasses. Two ...

Recombination Dynamics in Thin-film Photovoltaic Materials via Time-resolved Microwave Conductivity

A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials such as organo-lead halide perovskites is presented. The perovskite film thickness and absorption coefficient are initially characterized by profilometry and UV-VIS absorption spectroscopy. Calibration of both laser power and cavity sensitivity is described in detail. A protocol for performing Flash-photolysis Time Resolved Microwave Conductivity (TRMC) experiments, a non-contact method of determining the conductivity of a material, is presented. A process for identifying the real and imaginary components of the complex conductivity by performing TRMC as a function of microwave frequency is given. Charge carrier dynamics are determined under different excitation regimes (including both power and wavelength). Techniques for distinguishing between direct and trap-mediated decay processes are presented and discussed. Results are modelled and interpreted with reference to a general kinetic model of photoinduced charge carriers in a semiconductor. The techniques described are applicable to a wide range of optoelectronic materials, including organic and inorganic photovoltaic materials, nanoparticles, and conducting/semiconducting thin films.

A Time Resolved Microwave Conductivity technique for investigating direct and trap-mediated recombination dynamics and determining carrier mobilities of thin film semiconductors is presented here.

Zaman çözülmesi Mikrodalga İletkenlik aracılığıyla İnce film Fotovoltaik Malzemeler rekombinasyon Dinamikleri

A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials ...

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve desired molecular orientation states in LC displays, the "static" surface property of LCs, so-called surface anchoring, has been intensively studied. As a rule of thumb, once the initial orientation of LCs is "locked" by specific surface treatments, such as rubbing or treatment with a specific alignment layer, it hardly changes with temperature. Here, we present a system exhibiting an orientational transition upon temperature variation, which conflicts with the consensus. Right on the transition, the bulk LC molecules experience the orientational rotation, with 90&#176; between the planar (P) orientation at high temperatures and the vertical (V) orientation at low temperatures in the first-order transitional manner. We have tracked thermodynamic surface anchoring behavior by means of polarizing optical microscopy (POM), dielectric spectroscopy (DS), high-resolution differential scanning calorimetry (HR-DSC), and grazing incidence X-ray diffraction (GI-XRD) and reached a plausible physical explanation: that the transition is triggered by a growth of surface wetting sheets, which impose the V orientation locally against the P orientation in the bulk. This landscape would provide a general link explaining how the equilibrium bulk orientation is affected by surface-localized orientation in many LC systems. In our characterization, POM and DS are advantageous by offering information on the spatial distribution of the orientation of LC molecules. HR-DSC gives information about the precise thermodynamic information on transitions, which cannot be addressed by conventional DSC instruments due to limited resolution. GI-XRD provides information on surface-specific molecular orientation and short-range orderings. The goal of this paper is to present a protocol for preparing a sample that exhibits the transition and to demonstrate how the thermodynamic structural variation, both in the bulk and on surfaces, can be analyzed through the abovementioned methods.

Here, we present a protocol to trigger an orientational transition of a liquid crystal in response to temperature. Methodologies are described for preparing a sample in order to observe the transition and the detailed transitional evolution.

Yüzey Islatma Levhalarının Termodinamik Büyümesi ile tetiklenen Sıvı Kristalde Oryantasyon Geçişi

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve ...

Preparation of Liquid Crystal Networks for Macroscopic Oscillatory Motion Induced by Light

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous light irradiation. The photo-excitation of dopants that can quickly dissipate light into heat, coupled with anisotropic thermal expansion and self-shadowing of the film, gives rise to the self-sustained deformation. The oscillations observed are influenced by the dimensions and the modulus of the film, and by the directionality and intensity of the light. The system developed offers applications in energy conversion and harvesting for soft-robotics and automated systems.
The general method described here consists of creating free-standing liquid crystalline films and characterizing the mechanical and thermal effects observed. The molecular alignment is achieved using alignment layers (rubbed polyimide), commonly used in the display manufacturing industry. To obtain actuators with large deformation, the mesogens are aligned and polymerized in a splay/bend configuration, i.e., with the director of the liquid crystals (LCs) going gradually from planar to homeotropic through the film thickness. Upon irradiation, the mechanical and thermal oscillations obtained are monitored with a high-speed camera. The results are further quantified by image analysis using an image processing program.

The goal of the protocol is to create liquid crystalline polymer films that can mechanically oscillate under continuous light irradiation. We describe in great detail the conception of free-standing films, from the liquid crystal alignment method to the photo-actuation. The experimental protocol applied to prepare this material is broadly applicable.

Işık tarafından indüklenen makroskopik salınım hareketi için sıvı kristal ağlar hazırlanması

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous ...

Bulk and Thin Film Synthesis of Compositionally Variant Entropy-stabilized Oxides

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (Cu variant) entropy-stabilized oxides. Phase pure and chemically homogeneous (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (x = 0.20, 0.27, 0.33) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (x = 0.11, 0.27) ceramic pellets are synthesized and used in the deposition of ultra-high quality, phase pure, single crystalline thin films of the target stoichiometry. A detailed methodology for the deposition of smooth, chemically homogeneous, entropy-stabilized oxide thin films by pulsed laser deposition on (001)-oriented MgO substrates is described. The phase and crystallinity of bulk and thin film materials are confirmed using X-ray diffraction. Composition and chemical homogeneity are confirmed by X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The surface topography of thin films is measured with scanning probe microscopy. The synthesis of high quality, single crystalline, entropy-stabilized oxide thin films enables the study of interface, size, strain, and disorder effects on the properties in this new class of highly disordered oxide materials.

The synthesis of high quality bulk and thin film (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O entropy-stabilized oxides is presented.

Toplu ve bileşimsel varyant entropi stabilize oksit ince Film sentezi

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and ...

Film Control to Study Contributions of Waves to Droplet Impact Dynamics on Thin Flowing Liquid Films

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous studies on flowing liquid films have neglected the contributions of spatial structures of waves to the impact outcome, while this has recently been shown to have a significant influence on the drop impact dynamics. In this report, we outline a step-by-step procedure to investigate the effect of periodic inlet forcing of a flowing liquid film leading to the production of spatiotemporally regular wave structures on drop impact dynamics. A function generator in connection with a solenoid valve is used to excite these spatiotemporally regular wave structures on the film surface while the impact dynamics of uniform-sized droplets are captured using a high-speed camera. Three distinct regions are then studied; viz. the capillary wave region preceding the large wave peak, the flat film region, and the wave hump region. The effects of important dimensionless quantities such as film Reynolds, drop Weber and Ohnesorge numbers parameterized by the film flow rate, drop speed, and drop size are also examined. Our results show interesting, hitherto undiscovered dynamics brought about by this application of film inlet forcing of the flowing film for both low and high inertia drops.

A protocol to study the contributions of waves to droplet impact dynamics on flowing liquid films is presented.

Katkıları için damlacık darbe dinamikleri ince akan sıvı filmler üzerinde dalgaların çalışmaya film denetimi

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous ...

Thin Film Composite Silicon Elastomers for Cell Culture and Skin Applications: Manufacturing and Characterization

In this protocol, we present methods to fabricate thin elastomer composite films for advanced cell culture applications and for the development of skin adhesives. Two different poly-(dimethyl siloxanes) (PDMS and soft skin adhesive (SSA)), have been used for in depth investigation of biological effects and adhesive characteristics. The composite films consist of a flexible backing layer and an adhesive top coating. Both layers have been manufactured by doctor blade application technique. In the present investigation, the adhesive behavior of the composite films has been investigated as a function of the layer thickness or a variation of the Young&#39;s modulus of the top layer. The Young&#39;s modulus of PDMS has been changed by varying the base to crosslinker mixing ratio. In addition, the thickness of SSA films has been varied from approx. 16 &#181;m to approx. 320 &#181;m. Scanning electron microscopy (SEM) and optical microscopy have been used for thickness measurements. The adhesive properties of elastomer films depend strongly on the film thickness, the Young&#39;s modulus of the polymers and surface characteristics. Therefore, normal adhesion of these films on glass substrates exhibiting smooth and rough surfaces has been investigated. Pull-off stress and work of separation are dependent on the mixing ratio of silicone elastomers.
Additionally, the thickness of the soft skin adhesive placed on top of a supportive backing layer has been varied in order to produce patches for skin applications. Cytotoxicity, proliferation and cellular adhesion of L929 murine fibroblasts on PDMS films (mixing ratio 10:1) and SSA films (mixing ratio 50:50) have been conducted. We have shown here, for the first time, the side by side comparison of thin composite films manufactured of both polymers and present the investigation of their biological- and adhesive properties.

A protocol for the manufacturing process of polymeric thin film composite structures possessing either different Young&#39;s moduli or thicknesses is presented. Films are produced for advanced cell culture studies or as skin adhesives.

İnce Film kompozit silikon elastomer hücre kültürü ve cilt uygulamaları için: üretim ve karakterizasyonu

In this protocol, we present methods to fabricate thin elastomer composite films for advanced cell culture applications and for the development of skin ...

Gelişim Biyolojisi

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal

Smart viscoelastic materials that respond to specific stimuli are one of the most attractive classes of materials important to future technologies, such as on-demand switchable adhesion technologies, actuators, molecular clutches, and nano-/microscopic mass transporters. Recently it was found that through a special solid-liquid transition, rheological properties can exhibit significant changes, thus providing suitable smart viscoelastic materials. However, designing materials with such a property is complex, and forward and backward switching times are usually long. Therefore, it is important to explore new working mechanisms to realize solid-liquid transitions, shorten the switching time, and enhance the contrast of rheological properties during switching. Here, a light-induced crystal-liquid phase transition is observed, which is characterized by means of polarizing light microscopy (POM), photorheometry, photo-differential scanning calorimetry (photo-DSC), and X-ray diffraction (XRD). The light-induced crystal-liquid phase transition presents key features such as (1) fast switching of crystal-liquid phases for both forward and backward reactions and (2) a high contrast ratio of viscoelasticity. In the characterization, POM is advantageous in offering information on the spatial distribution of LC molecule orientations, determining the type of liquid crystalline phases appearing in the material, and studying the orientation of LCs. Photorheometry allows measurement of a material&#8217;s rheological properties under light stimuli and can reveal the photorheological switching properties of materials. Photo-DSC is a technique to investigate thermodynamic information of materials in darkness and under light irradiation. Lastly, XRD allows studying of microscopic structures of materials. The goal of this article is to clearly present how to prepare and measure the discussed properties of a photorheological material.

This protocol demonstrates the preparation of a photorheological material that exhibits a solid phase, various liquid crystalline phases, and an isotropic liquid phase by increasing temperature. Presented here are methods for measuring the structure-viscoelasticity relationship of the material.

Twist-Bend Nematic Sıvı Kristalin Yüksek Kontrastlı ve Hızlı Fotoromatolojik Geçişi

Smart viscoelastic materials that respond to specific stimuli are one of the most attractive classes of materials important to future technologies, such ...