Os autores gostariam de agradecer James A. Forrest ajuda para a idéia inicial para esta técnica. 26 Este trabalho foi apoiado pelo financiamento da Universidade da Pensilvânia e foi parcialmente financiado pelo programa MRSEC da National Science Foundation sob concessão não. DMR-11- 20901, da Universidade da Pensilvânia.

1. Preparação de Cinema <ol><li> Pesar 0,04 g de poliestireno, e colocar num frasco de 30 ml. </li><li> Pesar 2 g de tolueno para dentro do frasco. Uma solução a 2% em peso de poliestireno em tolueno produz um filme de cerca de 100 nm. </li><li> Deixe a solução sit O / N para dissolver totalmente o poliestireno e deixar que as soluções resolver. </li><li> Coloque uma pastilha de 1 cm x 1 cm de silício (Si) para um Revestidor rotação. </li><li> Girar a bolacha a 8.000 rpm durante 45 seg. Enquanto está girando, gota cerca de 1 ml de tolueno na bolacha de fiação. Nota: Todas as etapas que envolvem o revestimento de spin são realizadas em uma coifa. </li><li> Por agora estacionária bolacha de Si, adicionar a solução do passo 1.3, gota a gota sobre a bolacha de Si até que toda a superfície da bolacha de Si é coberto. </li><li> Antes de a solução seque sobre a bolacha, girar a bolacha de Si a 4.000 rpm durante 20 segundos. </li><li> Determinar a espessura do filme utilizando elipsometria (ver Passo 2). </li><li> Se o filme é a espessura desejada, Anneal a película numa estufa de vácuo a 393 K durante 15 horas. </li></ol> 2. Determinar espessura de filme <ol><li> Coloque o filme fundido girou para o palco elipsómetro e medir os ângulos ellipsometric Ψ (λ) e Δ (λ) em um ângulo de luz incidente de 70 ° com um tempo de aquisição de 1 seg e a definição de fuso média ligado. </li><li> Utilizando o software de elipsometria, encaixar o Ψ resultante (λ) e dados Δ (λ) a um modelo de três camadas de acordo com o protocolo do fabricante. Não há entradas adicionais do usuário. A primeira camada é uma camada de substrato de Si, a segunda camada é uma camada de óxido nativo com uma espessura de 1,5 nm, e a terceira camada é um modelo de Cauchy (N = A + B / λ 2, k = 0), o que corresponde para as propriedades ópticas da película de poliestireno. Neste modelo, A e B são parâmetros de ajuste, e n e k são as componentes reais e imaginários do índice de refracção de o, respectivamente. </li><li> Para a camada de Cauchy, caber a thickness e os parâmetros A e B se o filme for superior a 10 nm. Se o filme for inferior a 10 nm, só cabem A. Nota: Isso será discutido mais adiante na seção Resultados Representante. </li></ol> 3. Taxa de resfriamento T Dependente g Medidas <ol><li> Revestir a superfície do elemento de aquecimento da etapa de temperatura variável elipsómetro com pasta térmica. </li><li> Coloque a película de poliestireno recozido sobre o elemento de aquecimento. </li><li> Apertar a película firmemente sobre o elemento de aquecimento. </li><li> Fluxo de 100% de gás de azoto seco através da fase de temperatura a uma pressão de &lt;69 kPa. </li><li> Utilizando o software de fase temperatura, criação de um perfil de temperatura. Este perfil de temperaturas inicia-se com uma rampa de aquecimento de 393 K a 150 K / min. Segurar a película no 393K durante 20 min. <ol><li> Em seguida, as rampas de arrefecimento alternativos para 293 K em taxas de 150, 120, 90, 60, 30, 10, 7, 3, 1 e K / min, com rampas de aquecimento a 393 K a 150 K / min. Coloque a 5 min temperature espera depois de cada rampa. </li></ol></li><li> No software elipsometria, fazer um modelo elipsometria dependente da temperatura semelhante à da secção 2. Todas as três camadas são os mesmos, excepto que o substrato é alterado para um modelo de Si dependente da temperatura. </li><li> Na camada para o modelo Si dependente da temperatura, ative a opção &quot;Usar Ext Temp de Parm Log&quot; Parameter. </li><li> Usando equipamentos de laboratório software controlador, tem o software elipsómetro ler os valores de temperatura do estágio de temperatura. </li><li> Alinhar a elipsometria de tal modo que o sinal atinge a máxima intensidade. </li><li> Em &quot;Configurações Editar hardware&quot;, defina o tempo de aquisição rápida de 1 segundo com zona de alta precisão média. Defina o tempo normal de aquisição de 3 segundos com zona de alta precisão média. </li><li> Sob o &quot;in situ&quot; guia no software elipsómetro verificar o &quot;modo de aquisição rápido tempo de&quot; caixa e pressione &quot;Start Acquisition&quot;. Em seguida, inicieo perfil de temperatura. Antes da rampa de 3 K / min de arrefecimento, desmarque a caixa rápido tempo de aquisição. </li></ol> 4. Determinação de valores de T g <ol><li> Exportar a temperatura e perfis de espessura para a gráfica e software de análise preferido, e separar os dados de temperatura e espessura para todas as taxas de resfriamento 9. </li><li> A fim de explicar o efeito da zona média durante a aquisição da temperatura, tomar todos os valores de temperatura, e média, com o valor de temperatura que o precede, tais que T = (T i + t i-1) / 2, em que T I é um valor de temperatura num determinado momento, e T I-1 é a temperatura do ponto de tempo anterior. </li><li> Plot Espessura vs. temperatura para cada taxa de resfriamento. </li><li> Executar um ajuste linear sobre uma parte do regime de líquido super arrefecida (o regime de temperatura elevada com o coeficiente de dilatação maior). Este regime será de cerca de 393 K e 380 K. </li><li> PerfoRM um ajuste linear sobre uma parte do regime de vítreo que mesmo conjunto de dados. Este regime tem um coeficiente de dilatação inferior, e será a partir de cerca de 293 K e 340 K. </li><li> Encontre o ponto de intersecção dessas duas linhas. A temperatura onde estas linhas se cruzam representa a temperatura de transição vítrea. </li><li> Faça isso para todas as nove rampas. </li></ol> 5. Analisando Média Thin Film Dynamics <ol><li> Para um determinado lote de espessura de filme Log (resfriamento Rate (K / min)) vs. 1 / T g (K-1). </li><li> Compare isso indiretamente à medição da massa e de superfície dinâmica dirigir pela relação empírica: Arrefecimento Rate * τ α = 1000. 23,24 </li></ol>

<ol>
	<li>Keddie, J. L., Jones, R. A. L., Cory, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Size-Dependent+depression+of+the+glass+transition+temperature+in+polymer+films.">Size-Dependent depression of the glass transition temperature in polymer films.</a> Europhys. Lett. 27 (1), 59-64 (1994).</li><li>Forrest, J. A., Veress, K. D., Dutcher, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interface+and+chain+confinement+effects+on+the+glass+transition+temperature+of+thin+polymer+films.">Interface and chain confinement effects on the glass transition temperature of thin polymer films.</a> Phys. Rev.E. 56 (5), 5705-5716 (1997).</li><li>Forrest, J. A., Mattsson, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reductions+of+the+glass+transition+temperature+in+thin+polymer+films:+Probing+the+length+scale+of+cooperative+dynamics.">Reductions of the glass transition temperature in thin polymer films: Probing the length scale of cooperative dynamics.</a> Phys. Rev.E. 61 (1), R53-R56 (2000).</li><li>Sharp, J. S., Forrest, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Free+surfaces+cause+reductions+in+the+glass+transition+temperature+of+thin+polystyrene+films.">Free surfaces cause reductions in the glass transition temperature of thin polystyrene films.</a> PRL. 91 (23), 235701 (2003).</li><li>Ellison, C. J., Torkelson, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+distribution+of+glass-transition+temperatures+in+nanoscopically+confined+glass+formers.">The distribution of glass-transition temperatures in nanoscopically confined glass formers.</a> Nat. Mat. 2 (10), 695-700 (2003).</li><li>Priestley, R. D., Ellison, C. J., Broadbelt, L. J., Torkelson, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+relaxation+of+polymer+glasses+at+surfaces,+interfaces,+and+in+between.">Structural relaxation of polymer glasses at surfaces, interfaces, and in between.</a> Science. 309 (5733), 456-459 (2005).</li><li>Ellison, C. J., Kim, S. D., Hall, D. B., Torkelson, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Confinement+and+processing+effects+on+glass+transition+temperature+and+physical+aging+in+ultrathin+polymer+films:+Novel+fluorescence+measurements.">Confinement and processing effects on glass transition temperature and physical aging in ultrathin polymer films: Novel fluorescence measurements.</a> Euro. Phys. J. E. 8 (2), 155-166 (2002).</li><li>Ellison, C. J., Mundra, M. K., Torkelson, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impacts+of+polystyrene+molecular+weight+and+modification+to+the+repeat+unit+structure+on+the+glass+Transition&#8722;Nanoconfinement+effect+and+the+cooperativity+length+scale.">Impacts of polystyrene molecular weight and modification to the repeat unit structure on the glass Transition&#8722;Nanoconfinement effect and the cooperativity length scale.</a> Macromolecules. 38 (5), 1767-1778 (2005).</li><li>Yang, Z., Fujii, Y., Lee, F. K., Lam, C. H., Tsui, O. K. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glass+transition+dynamics+and+surface+layer+mobility+in+unentangled+polystyrene+films.">Glass transition dynamics and surface layer mobility in unentangled polystyrene films.</a> Science. 328 (5986), 1676-1679 (2010).</li><li>Tsui, O. K. C., Zhang, H. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+chain+ends+and+chain+entanglement+on+the+glass+transition+temperature+of+polymer+thin+films.">Effects of chain ends and chain entanglement on the glass transition temperature of polymer thin films.</a> Macromolecules. 34 (26), 9139-9142 (2001).</li><li>Roth, C. B., Dutcher, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glass+Transition+and+Chain+Mobility+in+thin+Polymer+Films.">Glass Transition and Chain Mobility in thin Polymer Films.</a> J. Electroanal. Chem. 584, 13-22 (2005).</li><li>Ediger, M. D., Forrest, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamics+near+Free+Surfaces+and+the+Glass+Transition+in+Thin+Polymer+Films:+A+View+to+the+Future.">Dynamics near Free Surfaces and the Glass Transition in Thin Polymer Films: A View to the Future.</a> Macromolecules. 47 (2), 471-478 (2014).</li><li>Serghei, A., Huth, H., Schick, C., Kremer, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glassy+dynamics+in+thin+polymer+layers+having+a+free+upper+interface.">Glassy dynamics in thin polymer layers having a free upper interface.</a> Macromolecules. 41 (10), 3636-3639 (2008).</li><li>Huth, H., Minakov, A. A., Schick, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+AC-chip+calorimeter+for+glass+transition+measurements+in+ultrathin+films.">Differential AC-chip calorimeter for glass transition measurements in ultrathin films.</a> J. Polym. Sci. B. 44 (20), 2996-3005 (2006).</li><li>Tress, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glassy+dynamics+in+condensed+isolated+polymer+chains.">Glassy dynamics in condensed isolated polymer chains.</a> Science. 341 (6152), 1371-1374 (2013).</li><li>Boucher, V. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=T+g+depression+and+invariant+segmental+dynamics+in+polystyrene+thin+films.">T g depression and invariant segmental dynamics in polystyrene thin films.</a> Soft Matter. 8 (19), 5119-5122 (2012).</li><li>Yu, M., Olson, E. A., Zhang, M., Zhang, Z., Allen, L. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glass+transition+in+ultrathin+polymer+films:+Calorimetric+study.">Glass transition in ultrathin polymer films: Calorimetric study.</a> PRL. 91 (8), 085703 (2003).</li><li>Kremer, F., Tress, M., Mapesa, E. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glassy+dynamics+and+glass+transition+in+nanometric+layers+and+films:+A+silver+lining+on+the+horizon.">Glassy dynamics and glass transition in nanometric layers and films: A silver lining on the horizon.</a> J. Non-Crys. Solids. 407, 277-283 (2015).</li><li>Qi, D., Ilton, M., Forrest, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+surface+and+bulk+relaxation+in+glassy+polymers.">Measuring surface and bulk relaxation in glassy polymers.</a> Euro. Phys. J. E. 34 (6), 1-7 (2011).</li><li>Teichroeb, J. H., Forrest, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+imaging+of+nanoparticle+embedding+to+probe+viscoelasticity+of+polymer+surfaces.">Direct imaging of nanoparticle embedding to probe viscoelasticity of polymer surfaces.</a> PRL. 91 (1), 016104 (2003).</li><li>Fakhraai, Z., Forrest, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+the+surface+dynamics+of+glassy+polymers.">Measuring the surface dynamics of glassy polymers.</a> Science. 319 (5863), 600-604 (2008).</li><li>Paeng, K., Swallen, S. F., Ediger, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+measurement+of+molecular+motion+in+freestanding+polystyrene+thin+films.">Direct measurement of molecular motion in freestanding polystyrene thin films.</a> J. Am. Chem. Soc. 133 (22), 8444-8447 (2011).</li><li>Glor, E. C., Fakhraai, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Facilitation+of+interfacial+dynamics+in+entagled+polymer+films.">Facilitation of interfacial dynamics in entagled polymer films.</a> JCP. 141 (9), 194505 (2014).</li><li>Fakhraai, Z., Forrest, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+slow+dynamics+in+supported+thin+polymer+films.">Probing slow dynamics in supported thin polymer films.</a> PRL. 95 (2), 025701 (2005).</li><li>Roth, C. B., McNerny, K. L., Jager, W. F., Torkelson, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Eliminating+the+enhanced+mobility+at+the+free+surface+of+polystyrene:+fluorescence+studies+of+the+glass+transition+temperature+in+thin+bilayer+films+of+immiscible+polymers.">Eliminating the enhanced mobility at the free surface of polystyrene: fluorescence studies of the glass transition temperature in thin bilayer films of immiscible polymers.</a> Macromolecules. 40 (7), 2568-2574 (2007).</li><li>Priestley, R. D., Ellison, C. J., Broadbelt, L. J., Torkelson, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+relaxation+of+polymer+glasses+at+surfaces,+interfaces,+and+in+between.">Structural relaxation of polymer glasses at surfaces, interfaces, and in between.</a> Science. 309 (5733), 456-459 (2005).</li><li>Gao, S., Koh, Y. P., Simon, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calorimetric+Glass+Transition+of+Single+Polystyrene+Ultrathin+Films.">Calorimetric Glass Transition of Single Polystyrene Ultrathin Films.</a> Macromolecules. 46 (92), 562-570 (2013).</li><li>Tropin, T. V., Schulz, G., Schmelzer, J. W. P., Schick, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heat+capacity+measurements+and+modeling+of+polystyrene+glass+transition+in+a+wide+range+of+cooling+rates.">Heat capacity measurements and modeling of polystyrene glass transition in a wide range of cooling rates.</a> J. Non-Cryst. Solids. 409, 63-75 (2015).</li><li>Kim, S., Hewlett, S. A., Roth, C. B., Torkelson, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Confinement+effects+of+glass+transition+temperature,+transition+breadth,+and+expansivity:+Comparison+of+ellipsometry+and+fluorescence+measurements+on+polystyrene+films.">Confinement effects of glass transition temperature, transition breadth, and expansivity: Comparison of ellipsometry and fluorescence measurements on polystyrene films.</a> Eur. Phys. J.E. 30, 83-92 (2009).</li><li>Schawe, J. E. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vitrification+in+a+wide+cooling+rate+range:+The+relations+between+cooling+rate,+relaxation+time,+transition+width+and+fragility.">Vitrification in a wide cooling rate range: The relations between cooling rate, relaxation time, transition width and fragility.</a> JCP. 141, 184905 (2014).</li><li>Donth, E., Korus, J., Hempel, E., Beiner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+DSC+heating+rate+and+HCS+frequency+at+the+glass+transition.">Comparison of DSC heating rate and HCS frequency at the glass transition.</a> Thermochimica Acta. 304-305, 239-249 (1997).</li><li>Zhang, C., Guo, Y., Priestley, R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Confined+glassy+properties+of+polymer+nanoparticles.">Confined glassy properties of polymer nanoparticles.</a> J. Polym. Sci. B. 51 (7), 574-586 (2013).</li><li>Koh, Y. P., Grassia, L., Simon, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+Recovery+of+a+Single+Polystyrene+Thin+Film+Using+Nanocalorimetry+to+Extend+the+Aging+Time+and+Temperature+Range.">Structural Recovery of a Single Polystyrene Thin Film Using Nanocalorimetry to Extend the Aging Time and Temperature Range.</a> Thermochimica Acta. 603, 135-141 (2015).</li><li>Gao, S., Simon, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+the+limiting+fictive+temperature+over+five+decades+of+cooling+and+heating+rates.">Measurement of the limiting fictive temperature over five decades of cooling and heating rates.</a> Thermochimica Acta. 603, 123-127 (2015).</li></ol>

The Authors have no conflicts of interest to disclose.

Arrefecimento da taxa de medições g T dependentes são experiências de caracterização de alto rendimento que podem determinar a Tg, o coeficiente de dilatação do vidro e o líquido super-resfriado, a dependência da temperatura da dinâmica médios, e a fragilidade de um material vítreo particular numa experiência única. Além disso, ao contrário de fluorescência, a incorporação, ou experiências de relaxação nanohole, g experiências CR-T são relativamente simples e rá...

O trabalho seminal de Keddie Jones e Corey 1 mostrou que a temperatura de transição vítrea (Tg) dos filmes finos de poliestireno ultra-diminui em relação ao valor de grandes quantidades a uma espessura inferior a 60 nm. Desde então, diversos estudos experimentais 2-11 apoiaram a hipótese de que as reduções observadas na Tg são causadas por uma camada de mobilidade aumentada próximo da superfície livre desses filmes. No entanto, estas experiências são medidas indirectas de um único tempo de relaxamento, e, portanto, existe um debate 12- 18 centrado sobre uma correlação directa entre o número de dinâmica de película fina e da dinâmica na interface ar / polímero. Para responder a este debate, muitos estudos têm medido diretamente a dinâmica da superfície livre (superfície τ). Incorporação de nanopartículas, 19,20 nanohole relaxamento, 21 e 22 de fluorescência estudos mostram que o ar / polímero de interface hcomo dinâmica ordens de grandeza mais rápido do que o tempo de relaxamento alfa granel (τ α) com uma dependência da temperatura muito mais fraca do que a de τ α. Devido à sua fraca dependência da temperatura, a superfície τ desses filmes, 19-22 e dinâmica melhoradas de filmes finos de poliestireno, 23,24 intersecta o relaxamento alfa granel (τ ct) a um único ponto T *, o qual é poucos graus acima T g, e a uma α τ ≈ de 1 seg. A presença de T * poderia explicar por que experiências que sondam tempos de relaxação mais rápido do que * não conseguem ver qualquer dependência espessura na T g de filmes ultrafinos de poliestireno. 13-18 Por último, enquanto medições diretas da camada reforçada espetáculo móvel que tem uma espessura de 4-8 nm, 20-22, há evidências de que o comprimento de propagação da dinâmica na interface ar / polímero é muito maior do que a espessura da superfície móvel Layer. 5,25-26 Este relatório tem como objetivo descrever completamente um protocolo para o uso de elipsometria para o arrefecimento da taxa dependente T g (CR-T g) experimentos. CR-Tg foram anteriormente utilizados para descrever a dinâmica médios de filmes ultra-finos de poliestireno. 23,24,27,28 Além disso, esta técnica foi usada recentemente para mostrar uma correlação directa entre a dinâmica médios em filmes ultrafinos de poliestireno , e a dinâmica na superfície livre 23 A vantagem de CR-T medições de g sobre outros tipos de medições, tais como fluorescência, nanopartículas incorporação, nanohole relaxamento, nanocalorimetry, espectroscopia de dieléctrico, e de Brillouin espalhamento de luz., estudos é que eles são relativamente rápidos e experiências simples que não utilizam fluoróforos ou outras técnicas experimentais complicados. Os avanços recentes em elipsometria espectroscópica permitir que esta técnica para ser utilizado para determinar a eficiência óptica properts de filmes ultra-finos de polímeros e outros tipos de materiais híbridos com precisão excepcional. Como tal, esta técnica investiga a dinâmica médios de filmes finos tecnologicamente aplicável em regimes de temperatura e de tempo relevantes para a transição vítrea (Tg ≤, τ α ≥ 100 seg). Além disso, esta técnica fornece informação sobre os coeficientes de expansão do vítreo e ceia arrefecida estados líquidos, assim como a fragilidade do sistema, o qual pode então ser comparado com os dados para os filmes a granel. Finalmente, experiências g CR T pode ser usado para qualquer sistema vítreo, desde que a integridade da película mantém-se durante todo o experimento.

<table border="0" cellpadding="0" cellspacing="0" width="918">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Toluene</td>
			<td style="width:111px;">Sigma Aldrich</td>
			<td style="width:119px;">179418-1L</td>
			<td style="width:472px;">This can be purchased from any chemical company.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Atactic Polystyrene</td>
			<td style="width:111px;">Polymer Source Inc.</td>
			<td style="width:119px;">P-4092-S</td>
			<td>This can be purchased from any chemical company.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">THMS 600 temperature stage</td>
			<td style="width:111px;">Linkam</td>
			<td style="width:119px;">THMS 600</td>
			<td>any temperature stage that can be fit to an ellipsometer could be used.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">M2000V Spectroscopic Ellipsometer</td>
			<td style="width:111px;">J.A. Woollam</td>
			<td style="width:119px;">M200V</td>
			<td>This procedure should be applicable for any spectroscopic ellipsometer.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Spin Coater</td>
			<td style="width:111px;">Laurell Technologies</td>
			<td style="width:119px;">WS-650-23B</td>
			<td>This Procedure is possible with any spin coater</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sample vials</td>
			<td style="width:111px;">Fisher Scientific</td>
			<td style="width:119px;">02-912-379</td>
			<td>Any sample vials will do</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Silicon wafers</td>
			<td style="width:111px;">Virginia semi conductors</td>
			<td style="width:119px;">325S1410694D</td>
			<td></td>
		</tr>
	</tbody>
</table>

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

Este relatório tem como objetivo descrever totalmente a técnica experimental de usar elipsometria para o arrefecimento da taxa dependente T g (CR-T g) experimentos. Estas medições são experiências de caracterização de alto rendimento simples, que pode determinar a temperatura de transição vítrea (T g), dinâmica médios, fragilidade e o coeficiente de expansão dos estados líquido e super-arrefecida vítreos para uma variedade de materiais vítreos. Esta técnica permite a estes parâmetros a serem medidos numa única experiência, enquanto que outros métodos de combinar uma variedade de técnicas diferentes para investigar todas estas propriedades. As medições da dinâmica fechar a Tg é particularmente difícil. A vantagem da taxa de resfriamento medições dependentes T g ao longo de outros métodos que sondam directamente dinâmica a granel e de relaxação de superfície é que elas são experiências relativamente rápida e simples, que não utilizam fluoróforos ou outro ex complicadotécnicas rimentais. Além disso, esta técnica de sondas médias a dinâmica de películas finas tecnologicamente relevantes de temperatura e tempo de relaxação (τ α) que sejam relevantes para a transição de vidro (τ α&gt; 100 seg). A limitação ao uso de elipsometria de arrefecimento de taxa dependente T g experiências é que ele não pode sondar tempos de relaxação relevantes para medições de viscosidade (τ α &lt;&lt; 1 seg). Outras técnicas de medição dependente T g da taxa de arrefecimento, no entanto, pode estender o método g CR-T para tempos de relaxação mais rápidos. Além disso, esta técnica pode ser usado para qualquer sistema vítreo, desde que a integridade da película mantém-se durante todo o experimento.

Fitting Raw Elipsometria Dados Filmes de poliestireno são transparentes na faixa de comprimento de onda da elipsómetro (500-1,600 nm). Assim, um modelo de Cauchy é um bom modelo para descrever o índice de refracção das películas de poliestireno. A Figura 1A mostra um exemplo de Ψ (λ) e Δ (λ) para uma espessura (274 nm) de filme de poliestireno, e o ajuste resultante à modelo Cauchy...

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

Aqui, apresentamos um protocolo para o arrefecimento das taxas de experimentos dependentes elipsometria, que pode determinar a temperatura de transição vítrea (Tg), dinâmica de fragilidade e médios, o coeficiente de expansão do líquido super-resfriado e vidro para uma variedade de materiais vítreos.

Arrefecimento Medidas de freqüência Elipsometria Dependentes para determinar a dinâmica de finas Glassy Films

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

Research

JoVE Journal

Chemistry

8.1K visualizações.  University of Pennsylvania.  Aqui, apresentamos um protocolo para o arrefecimento das taxas de experimentos dependentes elipsometria, que pode determinar a temperatura de transição vítrea (Tg), dinâmica de fragilidade e médios, o coeficiente de expansão do líquido super-resfriado e vidro para uma variedade de materiais vítreos. 

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

Thin-layer Chromatographic (TLC) Separations and Bioassays of Plant Extracts to Identify Antimicrobial Compounds

A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the chromatograms to microbial suspensions (e.g. fungi or bacteria in broth or agar), allowing time for the microbes to grow in a humid environment, and visualizing zones with no microbial growth.&#160;The effectiveness of this screening method, known as bioautography, depends on both the quality of the chromatographic separation and the care taken with microbial culture conditions.&#160;This paper describes standard protocols for TLC and contact bioautography&#160;with a novel application to amino acid-fermenting bacteria. The extract is separated on flexible (aluminum-backed) silica TLC plates, and bands are visualized under ultraviolet (UV) light.&#160;Zones are cut out and incubated face down onto agar inoculated with the test microorganism.&#160;Inhibitory bands are visualized by staining the agar plates with tetrazolium red.&#160;The method is applied to the separation of red clover (Trifolium pratense cv. Kenland) phenolic compounds and their screening for activity against Clostridium sticklandii, a hyper ammonia-producing bacterium (HAB) that is native to the bovine rumen.&#160;The TLC methods apply to many types of plant extracts&#160;and other bacterial species (aerobic or anaerobic), as well as fungi, can be used as test organisms if culture conditions are modified to fit the growth requirements of the species.

Thin-layer Chromatographic TLC Separations and Bioassays of Plant Extracts to Identify Antimicrobial Compounds

Methods are described for thin-layer chromatographic (TLC) separation of plant extracts and contact bioautography to identify antibacterial metabolites. The methods are applied to the screening of red clover phenolic compounds inhibiting hyper&#160;ammonia-producing bacteria (HAB) native to the bovine rumen.

Cromatográfica em camada delgada (TLC) Separações e Bioensaios de extratos de plantas para identificar compostos antimicrobianos

A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the ...

Química

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

Templates atomicamente definidos para crescimento epitaxial do Complexo Óxido Filmes Finos

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

High Precision Zinc Isotopic Measurements Applied to Mouse Organs

We present a procedure to measure with high precision zinc isotope ratios in mouse organs. Zinc is composed of 5 stable isotopes (64Zn, 66Zn, 67Zn, 68Zn and 70Zn) which are naturally fractionated between mouse organs. We first show how to dissolve the different organs in order to free the Zn atoms; this step is realized by a mixture of HNO3 and H2O2. We then purify the zinc atoms from all the other elements, in particular from isobaric interferences (e.g., Ni), by anion-exchange chromatography in a dilute HBr/HNO3 medium. These first two steps are performed in a clean laboratory using high purity chemicals. Finally, the isotope ratios are measured by using a multi-collector inductively-coupled-plasma mass-spectrometer, in low resolution. The samples are injected using a spray chamber and the isotopic fractionation induced by the mass-spectrometer is corrected by comparing the ratio of the samples to the ratio of a standard (standard bracketing technique).&#160;This full typical&#160;procedure produces an isotope ratio with a 50 ppm (2 s.d.) reproducibility.

We present the technique to measure with high precision zinc isotope ratios in mouse organs.

Medições de alta precisão de zinco isotópicas Aplicadas à mouse Órgãos

We present a procedure to measure with high precision zinc isotope ratios in mouse organs. Zinc is composed of 5 stable isotopes (64Zn, 66Zn, 67Zn, 68Zn ...

Fabrication of Large-area Free-standing Ultrathin Polymer Films

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films. Typically, ultrathin films are prepared using either sacrificial layers, which may damage the film or affect its mechanical properties, or they are made on freshly cleaved mica, a substrate that is difficult to scale. Further, the size of ultrathin film is typically limited to a few square millimeters. In this method, we modify a surface with a polyelectrolyte that alters the strength of adhesion between polymer and deposition substrate. The polyelectrolyte can be shown to remain on the wafer using spectroscopy, and a treated wafer can be used to produce multiple films, indicating that at best minimal amounts of the polyelectrolyte are added to the film. The process has thus far been shown to be limited in scalability only by the size of the coating equipment, and is expected to be readily scalable to industrial processes. In this study, the protocol for making the solutions, preparing the deposition surface, and producing the films is described.

We describe a method for the fabrication of large-area (up to 13 cm diameter) and ultrathin (as thin as 8 nm) polymer films. Instead of using a sacrificial interlayer to delaminate the film from its substrate, we use a self-limiting surface treatment suitable for arbitrarily large areas.

Fabricação de grande-área royalty-pé ultrafinos Polymer Films

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films.  Typically, ultrathin films are prepared ...

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes

Enzyme catalysis evolved in an aqueous environment. The influence of solvent dynamics on catalysis is, however, currently poorly understood and usually neglected. The study of water dynamics in enzymes and the associated thermodynamical consequences is highly complex and has involved computer simulations, nuclear magnetic resonance (NMR) experiments, and calorimetry. Water tunnels that connect the active site with the surrounding solvent are key to solvent displacement and dynamics. The protocol herein allows for the engineering of these motifs for water transport, which affects specificity, activity and thermodynamics. By providing a biophysical framework founded on theory and experiments, the method presented herein can be used by researchers without previous expertise in computer modeling or biophysical chemistry. The method will advance our understanding of enzyme catalysis on the molecular level by measuring the enthalpic and entropic changes associated with catalysis by enzyme variants with obstructed water tunnels. The protocol can be used for the study of membrane-bound enzymes and other complex systems. This will enhance our understanding of the importance of solvent reorganization in catalysis as well as provide new catalytic strategies in protein design and engineering.

Channels for the transportation of water molecules in enzymes influence active site solvation and catalysis. Herein we present a protocol for the engineering of these additional catalytic motifs based on in silico computer modeling and experiments. This will enhance our understanding of the influence of solvent dynamics on enzyme catalysis.

Desvendando Aceleração Entropic Taxa Induzida por solventes Dynamics na membrana Enzimas

Enzyme catalysis evolved in an aqueous environment. The influence of solvent dynamics on catalysis is, however, currently poorly understood and usually ...

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR

The main limitation of NMR-based investigations is low sensitivity. This prompts for long acquisition times, thus preventing real-time NMR measurements of metabolic transformations. Hyperpolarization via dissolution DNP circumvents part of the sensitivity issues thanks to the large out-of-equilibrium nuclear magnetization stemming from the electron-to-nucleus spin polarization transfer. The high NMR signal obtained can be used to monitor chemical reactions in real time. The downside of hyperpolarized NMR resides in the limited time window available for signal acquisition, which is usually on the order of the nuclear spin longitudinal relaxation time constant, T1, or, in favorable cases, on the order of the relaxation time constant associated with the singlet-state of coupled nuclei, TLLS. Cellular uptake of endogenous molecules and metabolic rates can provide essential information on tumor development and drug response. Numerous previous hyperpolarized NMR studies have demonstrated the relevancy of pyruvate as a metabolic substrate for monitoring enzymatic activity in vivo. This work provides a detailed description of the experimental setup and methods required for the study of enzymatic reactions, in particular the pyruvate-to-lactate conversion rate in presence of lactate dehydrogenase (LDH), by hyperpolarized NMR.

The sensitivity enhancement provided by dissolution dynamic nuclear polarization (DNP) enables following metabolic processes in real time by NMR and MRI. The characteristics and performances of a dedicated dissolution DNP setup designed for study enzymatic reactions are discussed.

Dissolução dinâmico Nuclear Polarização Instrumentação para em tempo real enzimática Reaction Taxa de Medições por RMN

The main limitation of NMR-based investigations is low sensitivity. This prompts for long acquisition times, thus preventing real-time NMR measurements of ...

Capillary Electrophoresis to Monitor Peptide Grafting onto Chitosan Films in Real Time

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. Compared to other analytical separation techniques, such as chromatography, CE is cheap, robust and effectively requires no sample preparation (for a number of complex natural matrices or polymeric samples). CE is fast and can be used to follow the evolution of mixtures in real time (e.g., chemical reaction kinetics), as the signals observed for the separated compounds are directly proportional to their quantity in solution.
Here, the efficiency of CE is demonstrated for monitoring the covalent grafting of peptides onto chitosan films for subsequent biomedical applications. Chitosan&#39;s antimicrobial and biocompatible properties make it an attractive material for biomedical applications such as cell growth substrates. Covalently grafting the peptide RGDS (arginine - glycine - aspartic acid - serine) onto the surface of chitosan films aims at improving cell attachment. Historically, chromatography and amino acid analysis have been used to provide a direct measurement of the amount of grafted peptide. However, the fast separation and absence of sample preparation provided by CE enables equally accurate yet real-time monitoring of the peptide grafting process. CE is able to separate and quantify the different components of the reaction mixture: the (non-grafted) peptide and the chemical coupling agents. In this way the use of CE results in improved films for downstream applications.
The chitosan films were characterized through solid-state NMR (nuclear magnetic resonance) spectroscopy. This technique is more time-consuming and cannot be applied in real time, but yields a direct measurement of the peptide and thus validates the CE technique.

Free solution capillary electrophoresis is a fast, cheap and robust analytical method that enables the quantitative monitoring of chemical reactions in real time. Its utility for rapid, convenient and precise analysis is demonstrated here through analysis of covalent peptide grafting onto chitosan films for improved cell adhesion.

Eletroforese Capilar para monitorar Peptide Enxertia em quitosana Films em Tempo real

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Espectroscopia de impedância eletroquímica como uma ferramenta para estimativa de constante taxa eletroquímica

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. Conductive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), and a semiconducting polymer, poly(thieno[3,2-b]thiophene) (PTT), were deposited on unconventional highly-disordered and textured substrates with high surface areas, such as paper, towels and fabrics. This reported deposition chamber is an improvement of previous vapor reactors because our system can accommodate both volatile and nonvolatile monomers, such as 3,4-propylenedioxythiophene and thieno[3,2-b]thiophene. Utilization of both solid and liquid oxidants are also demonstrated. One limitation of this method is that it lacks sophisticated in situ thickness monitors. Polymer coatings made by the commonly used solution-based coating methods, such as spin-coating and surface grafting, are often not uniform or susceptible to mechanical degradation. This reported vapor phase deposition method overcomes those drawbacks and is a strong alternative to common solution-based coating methods. Notably, polymer films coated by the reported method are uniform and conformal on rough surfaces, even at a micrometer scale. This feature allows for future application of vapor deposited polymers in electronics devices on flexible and highly textured substrates.

This paper presents a protocol for reactive vapor deposition of poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), and poly(thieno[3,2-b]thiophene) films on glass slides and rough substrates, such as textiles and paper.

Depósito de Vapor reativa dos filmes de polímeros conjugados em substratos arbitrários

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. ...

Solution-Processed "Silver-Bismuth-Iodine" Ternary Thin Films for Lead-Free Photovoltaic Absorbers

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. However, poor surface morphologies and relatively high bandgap energies have limited their potential. Silver-bismuth-iodine (Ag-Bi-I) is a promising semiconductor for optoelectronic devices. Therefore, we demonstrate the fabrication of Ag-Bi-I ternary thin films using material solution processing. The resulting thin films exhibit controlled surface morphologies and optical bandgaps according to their thermal annealing temperatures. In addition, it has been reported that Ag-Bi-I ternary systems crystallize to AgBi2I7, Ag2BiI5, etc. according to the ratio of the precursor chemicals. The solution-processed AgBi2I7 thin films exhibit a cubic-phase crystal structure, dense, pinhole-free surface morphologies with grains ranging in size from 200 to 800 nm, and an indirect bandgap of 1.87 eV. The resultant AgBi2I7 thin films show good air stability and energy band diagrams, as well as surface morphologies and optical bandgaps suitable for lead-free and air-stable single-junction solar cells. Very recently, a solar cell with 4.3% power conversion efficiency was obtained by optimizing the Ag-Bi-I crystal compositions and solar cell device architectures.

Herein, we present detailed protocols for solution-processed silver-bismuth-iodine (Ag-Bi-I) ternary semiconductor thin films fabricated on TiO2-coated transparent electrodes and their potential application as air-stable and lead-free optoelectronic devices.

Solução-processados "Prata-bismuto-iodo" ternário filmes finos para absorventes de chumbo fotovoltaicos

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. ...