Yazarlar minnetle bu proje desteği Ulusal Bilim Vakfı (DMR-1409034) kabul edersiniz. Ayrıca National Institute of Standards ve ticaret, teknoloji, ABD Bakanlığı desteği nerede bu tesisleri kısmen sözleşme kapsamında Ulusal Bilim Vakfı tarafından desteklenen bu çalışmada kullanılan USANS imkanları sağlayan anıyoruz No DMR-0944772. Bu araştırmanın SANS deneyler, ORNL'ın yüksek akı izotop hangi bilimsel kullanıcı imkanları bölüm, temel Enerji Bilimler Office, bize Enerji Bakanlığı tarafından sponsor oldu reaktör, tamamlandı.

Kimyasal maddelerin tüm işleme uygun kişisel koruyucu ekipman ile ve bir emanet başlık içinde yapılmalıdır. Tüm örneklerini İyonlaştırıcı radyasyona maruz İmkanları radyoaktif denetim teknisyenleri gözetimi altında ele alınmalıdır. Bu iletişim kuralı uygun radyasyon güvenliği eğitimleri tamamlanmış olan kişiler tarafından gerçekleştirildi.
1. P3HT d-ODCB çözümlerinde hazırlanması
<ol>
	<li>Örnek alma
	<ol>
		<li>Yüksek regioregularity 1 g satın (&#62; % 90) P3HT moleküler ağırlık aralığı 15-40 K.</li>
		<li>5 g yüksek saflık satın (&#62; deuterated 90 atom %) d-4 1,2-ODCB.</li>
	</ol>
	</li>
	<li>Numune hazırlama
	<ol>
		<li>Tüm d-ODCB çözüm 0,45 µm elek ile cam şişe filtre.</li>
		<li>P3HT 0,34 g d-ODCB 5 g cam şişe içinde 1.66 g folyo kaplı kap ile birleştirin. Not: örnek oluşturma ve transfer süreci boyunca, hangi her zaman örnek gösterilir ortam ışık şiddeti en aza indirmek.</li>
		<li>Manyetik heyecan çubuğu eklemek için şişe kapağı güvenli ve parafilm ile mühür.</li>
		<li>Herhangi bir ışık çözüm amacıyla tamamen alüminyum folyo şişede sarın.</li>
		<li>Örnek 1-3 h için 70 ° c sıcak sac etkin olan manyetik heyecan çubuk yerleştirin.</li>
		<li>Isı ve çözüm (tercihen tam dağılım sağlamak için örnek Isıtma/karıştırma gecede bırakarak) tamamen homojen bir kez karıştırarak çıkarın.</li>
		<li>Çözüm şişe düzgün temizlenmiş için transfer (ile ayrı durular aseton ve su) cam pipet kullanarak 1 veya 2 mm kalınlığında kuvars banjo hücre. Not: cam pipet 70 ° c Isıtma fırında hemen transfer büyük ölçüde bu işlemi kolaylaştırır önce Isıtma.</li>
		<li>Banjo cep kapağı takmak ve parafilm ile mühür.</li>
		<li>Yer banjo karanlık hücreye (yani kapalı bir kutu içinde veya alüminyum folyo sarılı).</li>
		<li>Benzer şekilde sadece d-ODCB (için kapasiteli dolu) ve solvent arka plan ve boş hücre olarak saçılma deneyler için sırasıyla, hareket için bir boş banjo hücre içeren bir örnek bir araya getirin.</li>
	</ol>
	</li>
</ol>
2. nötron saçılma deneyler
<ol>
	<li>SANS "karanlık" ortamında deneyler
	<ol>
		<li>Enstrüman bilim adamı yardımı ile bir örnek sahne--dan 70-20 ° c sıcaklık rampa yönetmenlik yeteneğine sahip gerekli sıcaklık kontrol ile yapıştırılmış sağlamak</li>
		<li>Banjo hücreler uygun ölçekli holding bloklar, güvenli ve etiket yerleştirin.</li>
		<li>Tüm blok hiçbir ortam ışığı için örnek olay olduğundan emin olmak için 0,1 mm kalınlığında alüminyum folyo ile sarın. Deformasyonlar folyo sarılı blok uygun montaj içinde örnek sahne sağlamak için simge durumuna küçültün. Bu kaydırılan blok ve örnek içinde örnek sahne yerleştirin.</li>
		<li>Enstrüman bilim adamı yardımı ile uygun araç hizalama ve Kalibrasyon uygun Standart ölçüler kullanarak tamamlayın. Sonuçta a Q eksiksiz olarak kabaca 0,001-0,1 izin erişim vermek için en düşük Q bölge (Å ~0.001-1), (örneğin 18 m) ayarı ise en yakın dedektörü mesafe belirleyin Å-1. Bu uzunluğu sondalama 500 ~ ölçekler sağlayacaktır nm.</li>
		<li>Enstrüman bilim adamı yardımıyla sayısı oranları P3HT ve çözelti örnekleri için toplamak ve sağlanması toplam dedektörü sayıları yaklaşık 500.000 için 1.000.000, örnek başına elde etmek için gereken saçılma süreyi belirlemek için hesaplamalar istatistiksel kaliteli veri.</li>
		<li>Bu bilgileri kullanarak, 70-20 ° C sıcaklık rampa ve veri toplama işlemi doğrudan bir örnek komut dosyası oluşturun. Ayrı sıcaklık aralığı gizlemek için en iyi zaman kısıtlamaları içinde tüm aralığı işaret örneğin her 2 ° c seçin Her noktası rampa için komut dosyasında 3 ayrı giriş yapabilmeniz: istenilen sıcaklığa, sistemin saçılma toplanmadan önce termal equilibrate izin vermek için bir bekleme süresi (~ 15 dakika) ve saçılma ölçüm kendisi üzerinde yapılan bir değişiklik gerekli Dedektör elde etmek için uygun süre sayar</li>
		<li>Enstrüman ve komut dosyası hazırlanır sonra komut dosyasını yürütün ve deneme başlar. Solvent ve boş hücreyi de (olmadan sıcaklık rampa) veri toplamak emin olun. Buna ek olarak, iletim örnekleri engellenen ışını ölçüm verileri toplamak.</li>
	</ol>
	</li>
	<li>SANS "ışık" ortamında deneyler
	<ol>
		<li>"Karanlık" deneme tamamlandığında, örneklerini Sahne Alanı'ndan hareket üzerinde güvenli bir benchtop yer ve radyasyon güvenlik protokollerini kesilmediğini gözleyerek tüm alüminyum folyo kaldırın.</li>
		<li>Öyle ki müşteri adaylarını etkin bir şekilde örnek yuvası saçılma koleksiyonu pozisyonla ilişkili aşamasında aydınlatmak örnek sahne yakınındaki bir halojen ışık kaynağı içeren bir optik ışığı getirin.</li>
		<li>Kalibre edilmiş bir ışık ölçer, kayıt örnek nerede oturur pozisyonda en fazla yoğunluk, ışığı tarafından sağlanan ışık şiddeti kullanarak. Yoğunluk değerleri ışığı ve örnek sahne yapılandırma ile değişir, ancak, en az 5000 lux aydınlatma yoğunluğunu isteniyorsa.</li>
		<li>Bir kez bu aydınlatma kurulum düzgün monte, örnekleri Sahne Alanı'na dönün, ışığı düzgün etkin örnek aydınlatma sağlamak, tekrar 70 ° C ısı, uygun denge izin ve karanlık gerçekleştirilen veri toplama yordamı yineleyin örnekleri, bu adımın süresi kesintisiz doğrudan ışık pozlama ayrıntılı sağlayan optik ışığı ile.</li>
	</ol>
	</li>
	<li>USANS deneyleri
	<ol>
		<li>USANS örnekleri kuvars banjo hücreleri kullanarak benzer bir şekilde hazırlamak ve bakır veya titanyum bloklar halinde sıcaklık kontrollü örnek sahne alanı içinde yerleştirin.</li>
		<li>Enstrüman bilim adamı yardımıyla, hizalama ve arabellek kabaca 10-5 - 10-3 Å-1uzunluğu izin, Q değerlerinden analizine izin vermek için belirli nötron dalga boyu, gerekli sayısı istihdam enstrüman kalibre mikron sırasına probed için ölçeklendirir.</li>
		<li>Benzer bir şekilde sunan termal denge ve veri toplama daha önce okudu her sıcaklıkta SANS deneyler için deneysel komut dosyası geliştir.</li>
		<li>Tekrar SANS deneyler çoğaltmak için komut dosyası bir kez "karanlık" koşullar altında ve tekrar "" ışık"koşullarda.</li>
	</ol>
	</li>
</ol>
3.Veri azaltma ve analiz
<ol>
	<li>Azaltma ve analiz SANS
	<ol>
		<li>İlgili azaltma programı kullanarak,32 veri dosyaları saçılma, arka plan (solvent), boş hücre, engellenen kiriş ve uygun arka plan çıkarma ve mutlak saçılma veri dönüştürme gerçekleştirmek için iletim ölçümleri için giriş cm-1yoğunluğu birim.</li>
		<li>Uygun şekilde azaltılmış verilerle doğrusal olarak iki uygun denklemler, biri nanofibril toplamları eliptik silindir modeli,33 üzerinden temsil eden bir model için deneysel saçılma veri yaklaştırarak çözümlemesi'ni başlatmak ve polimer ile çözüme ücretsiz zincire dikkate alarak başka bir birim modeli hariç. 34 , 35 bu kombinasyon modeli yaklaşımı denklem aşağıda açıklanmaktadır: 
		<img alt="Equation 1" src="/files/ftp_upload/56163/56163eq1.jpg"> Bu denklemdeki ϕP3HT açıklar P3HT Toplam hacim kısmını çözümünde, <img alt="Equation 2" src="/files/ftp_upload/56163/56163eq2.jpg"> toplanan P3HT mevcut birim bölümüdür ve bir eliptik silindir PPEV örnek alınarak ücretsiz zinciri hariç birim değil P3HT, PECM için form faktörü eliptik silindir form faktörü için toplamları açıklar ve <img alt="Equation 3" src="/files/ftp_upload/56163/56163eq3.jpg"> ve <img alt="Equation 4" src="/files/ftp_upload/56163/56163eq4.jpg"> saçılma uzunluğu yoğunluğu (SLD) kontrast P3HT toplamları ve çözücü arasında arasında ücretsiz P3HT zincirleri ve Çözücü, anılan sıraya göre. SLD değerler sisteminin tüm bileşenler için onların kimyasal bir bilgi ile hesaplanan kompozisyon ve kütle yoğunluğu ve bir SLD hesap makinesi olarak kullanılabilir kullanımı yarı nötron analiz programları en veya online. 36</li>
		<li>Uygun montaj prosedürleri ışık ve karanlık, bir miktar izin tüm sıcaklıklar genellikle sistemi için anahtar yapısal parametreleri için değerleri elde NCNR Igor makrolar37 veya SASView uygun program uygun kullanma morfolojik evrim bu süreci boyunca meydana gelen sıcaklık ve ışık pozlama bir fonksiyonu olarak. Bu yapısal parametreleri nanofibrils kesitsel alanlar içerir, ücretsiz zinciri RADIUS Eylemsizlik (Rg) ve Porod üs ve malzeme nanofibril aşamasında mevcut toplam miktarın nitel bir değerlendirme.</li>
	</ol>
	</li>
	<li>USANS azaltma ve analiz
	<ol>
		<li>İlgili azaltma programı kullanarak, mutlak yoğunluğu birim cm-1tek azaltılmış eğrideki verileri birleştirmek her arabellek için arka plan veri ve saçılma veri girişi.</li>
		<li>Kantitatif değerlendirmesi toplama saçılma kalıplarının USANS uzunluk ölçek tarafından probed ve toplam Rg değerleri edinimi sağlar sağlayan bir Guinier-Porod güç hukuk modeli kullanarak veri analiz. 38 NCNR makrolar37 veya SASView uygun program uygun Igor bu yöntemle tüm sıcaklıklar ve aydınlatma koşulları arasında karşılaştırma makro-agrega Rg izin kullanmak uygun.</li>
	</ol>
	</li>
</ol>

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M., Reiter, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reversibly+Slowing+Dewetting+of+Conjugated+Polymers+by+Light.">Reversibly Slowing Dewetting of Conjugated Polymers by Light.</a> Macromolecules. 46, 2352-2356 (2013).</li><li>Botiz, I., 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=Enhancing+the+Photoluminescence+Emission+of+Conjugated+MEH-PPV+by+Light+Processing.">Enhancing the Photoluminescence Emission of Conjugated MEH-PPV by Light Processing.</a> ACS Appl. Mater. Interfaces. 6 (7), 4974-4979 (2014).</li><li>Morgan, B., Dadmun, 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=Illumination+Alters+the+Structure+of+Gels+Formed+from+the+Optoelectronic+Material+P3HT.">Illumination Alters the Structure of Gels Formed from the Optoelectronic Material P3HT.</a> Polymer. 108, 313-321 (2017).</li><li>Morgan, B., Dadmun, 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=Illumination+of+Conjugated+Polymer+in+Solution+Alters+Its+Conformation+and+Thermodynamics.">Illumination of Conjugated Polymer in Solution Alters Its Conformation and Thermodynamics.</a> Macromolecules. 49 (9), 3490-3496 (2016).</li><li>Ilavsk, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phase+Transition+in+Swollen+Gels.+2.+Effect+of+Charge+Concentration+on+the+Collapse+and+Mechanical+Behavior+of+Polyacrylamide+Networks.">Phase Transition in Swollen Gels. 2. Effect of Charge Concentration on the Collapse and Mechanical Behavior of Polyacrylamide Networks.</a> Macromolecules. 15, 782-788 (1982).</li><li>Tanaka, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collapse+of+Gels+and+the+Critical+Endpoint.">Collapse of Gels and the Critical Endpoint.</a> Phys. Rev. Lett. 40 (12), 820-823 (1978).</li><li>. SANS &amp; USANS Data Reduction and Analysis Available from: <a target="_blank" href="https://www.ncnr.nist.gov/programs/sans/data/red_anal.html">https://www.ncnr.nist.gov/programs/sans/data/red_anal.html</a> (2017)</li><li>Feigin, L., Svergun, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Structure Analysis by Small-Angle X-Ray and Neutron Scattering. , (1987).</li><li>Mittelbach, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zur+Rontgenkleinwinkelstreuung+verdunnter+kolloider+systeme.">Zur Rontgenkleinwinkelstreuung verdunnter kolloider systeme.</a> Acta Phys. Austriaca. 14, 185-211 (1961).</li><li>Schulz, G. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=&#220;ber+die+Kinetik+der+Kettenpolymerisationen.">&#220;ber die Kinetik der Kettenpolymerisationen.</a> Z. Phys. Chem. 43, 25 (1935).</li><li>. Neutron activation and scattering calculator Available from: <a target="_blank" href="https://www.ncnr.nist.gov/resources/activation">https://www.ncnr.nist.gov/resources/activation</a> (2017)</li><li>Kline, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+and+Analysis+of+SANS+and+USANS+Data+Using+IGOR+Pro.">Reduction and Analysis of SANS and USANS Data Using IGOR Pro.</a> J. Appl. Crystallogr. 39 (6), 895-900 (2006).</li><li>Guinier, A., Fournet, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Small-Angle Scattering of X-Rays. , (1955).</li></ol>

Yazarlar ifşa gerek yok.

İlk olarak, sıcaklık bir fonksiyonu olarak SANS verilere bakarak, eliptik silindir modeli ölçeklendirme etkeni artış P3HT hangi isconsistent jelleşme ilerleme ile işlemek nanofibril aşamasında mevcut miktarında belirgin bir artış gösterir . Aynı anda, bozulan termodinamik koşullar sıcaklık ile ilişkili azaltmak üs ortaya çıkarır bir zincir çöküş hala mevcut P3HT zincire neden olan Porod bir artış ile ücretsiz zinciri Rg azalma eşleştirilmiş çözüm. Kombine bir işaretli gös...

Konjüge polimerler gibi organik ışık yayan diyotlar, organik yarı iletkenler, kimyasal sensörler ve organik fotovoltaik cihazlar geniş aralığında kullanılan işlevsel malzemeler söz veriyorum. 1 , 2 , 3 , 4 , 5 , 6 sipariş ve etkin katman içinde katı hal konjuge polimer ambalaj bu cihazlar performansında önemli bir yönü var. 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 bu Morfoloji büyük ölçüde çözüm yanı sıra bu çözümler bir substrat döküm ve solvent kaldırılır gibi gelişmeye yapıları polimer zincirinin her iki biçimi tarafından önceden belirlenir. Uygun bir çözücü içinde mevcut bir modeli opto-elektronik polimer bir tipik sol-jel geçiş yapıları inceleyerek, bu sistemlerin etkili modellenebilir ve nicel bir bakış kendinden montajlı malzeme ifade sırasında oluşur elde edilebilir. 15 , 16 , 17 , 18 , 19 , 20
Özellikle, biz solvent deuterated Orto-dichlorobenzene (ODCB), organik elektronik cihaz imalat çeşitli kapsamlı kullanıma uygunluğu nedeniyle görülen bir polimer-çözücü sistemi içinde konjuge polimer kıyaslama P3HT incelemek teknikleri. 23 , 24 , 25 bu verilen çözelti ortamında, P3HT zincirler gibi uygun bir çevresel uyaranlara toplamak başlar sıcaklık azalması veya solvent kalite kaybı. Bu derleme işlemi bir önde gelen önerilen yollar ile soruşturma altında için kesin mekanizması nerede bireysel bir süreç olduğuna inanılan P3HT molekülleri π-yığın nanofibrils, daha sonra kendilerini bilinen lamel nano-toplamları oluşturmak için daha büyük mikron ölçek makro-toplamları oluşturmak üzere aglomera. 24 bu yollar ve oluşan sonuç yapıları anlayış doğru tahmin ve en uygun aygıt etkin katman türleri Morfoloji oluşumunu etkileyen anahtarıdır.
Daha doğrusu bu etkin katman mimarileri oluşumunu yönlendiren, bu nihai hedefi doğru dönüşlü konjuge polimer morfolojisi In-situ değiştirmek için ek deneysel ve endüstriyel yöntemler geliştirmek için bir ihtiyaç vardır. Pozlama ışık kullanımı ucuz bir araç olarak polimer zinciri Morfoloji, onun fizibilite doğru işaret sayısal ve deneysel sonuçlarla değiştirme etrafında bir nispeten yeni metodoloji merkezleri. 25 , 26 , 27 son bizim laboratuvar çalışmalarının bir ışık indüklenen değişiklik polimer zinciri boyutu aydınlatma üzerine önemli bir değişiklik için önde gelen bir seyreltik çözümde konjuge polimer-solvent etkileşimin varlığını belirtilen. 30 , 31 burada, etkili bir termostat kontrollü tarafından yönlendirilir bir jelleşme sürecinde doğrudan güneş ışığı çok daha yoğun bir konjüge polimer çözüm açığa etkilerini izleyerek bu çalışmaya devam etmek için bir iletişim kuralı mevcut Sıcaklık rampa. Uzunluğu ölçekten Angström mikron, bir yetenek daha yaygın diğer rheological veya spektroskopik enstrümantal mümkün değil üzerinde polimer-solvent sol-jel sisteminin yapısal parametreleri sağlam analiz sağlar gibi biz nötron saçılma istihdam yöntemleri. 16 , 17 , 30 , 31 bu nedenle düzgün analiz küçük ve ultra-küçük açı karşılaştırarak nötron veri jelleri Meclisi aydınlatma karanlıkta, toplanan aynı bilgiler yapısal farklılıklar aydınlatma tarafından tahrik getirdiği altında oluşan etkileri kapsamlı bir şekilde tespit ve sayılabilir.

<table><tbody><tr><td>M(106) poly(3-hexylthiophene-2,5-diyl) (P3HT)</td><td>Ossila</td><td>104934-50-1</td><td>Conjugated polymer</td></tr><tr><td>deuterated 1,2 ortho-dichlorobenzene (ODCB)</td><td>Sigma Aldrich</td><td>AC321260050</td><td>solvent</td></tr></tbody></table>

monitoring the effects of illumination on the structure of conjugated polymer gels using neutron scattering

Biz etkili bir yüksek konsantrasyon çözüm konjuge polimer hem varlığı ve yokluğu Beyaz ışığa maruz jelleşme işlemi izlemek için bir protokol göstermek. Onlar etkili organik çözüm ifade aşamasında deneyimli koşulları yansıtır bu yapısal evrim devam ederken bir ısı kontrollü rampa tesis tarafından bu malzemelerin jelleşme tam olarak izlenebilir elektronik cihaz fabrikasyon. Küçük açı nötron saçılma (San) ve ultra-küçük açı nötron saçılma (USANS) ile birlikte uygun montaj protokolleri kullanarak bu süreci boyunca select yapısal parametreleri evrimi ölçmek. Ayrıntılı analiz devam ışığa maruz jelleşme sürecinde önemli ölçüde sonuçta kurulan jel yapısını değiştirir gösterir. Özellikle, poly(3-hexylthiophene-2,5-diyl) (P3HT) nano ölçekli toplamları toplama işlemini olumsuz aydınlatma, sonuçta konjuge polimer microstructures büyüme geriliği sonuçlanan varlığı etkilenir ve küçük ölçekli makro-agrega kümeler oluşumu.

Deneyler yoluyla SANS ve USANS, P3HT jelleşme süreç d-ODCB içinde etkili bir şekilde dağınık çözümü devlet 70 ° C'de 20 ° C'de tam olarak genellikle bir duruma izlenirler yapıldı. Bu deneyler her iki karanlık ve beyaz ışık aydınlatma altında yapılmıştır. Şekil 1 Şekil 2' de gösterilen bu deneyler, uygun bir örnek eğrisi ile gelen bazı örnek azaltılmış SANS veri eğrilerini görüntüler. Bu ver...

Watch this Scientific Journal Video about Monitoring the Effects of Illumination on the Structure of Conjugated Polymer Gels Using Neutron Scattering at JoVE.com

Monitoring the Effects of Illumination on the Structure of Conjugated Polymer Gels Using Neutron Scattering

Bir iletişim kuralı Optoelektronik oluşan jelleri analizi için polimer poly(3-hexylthiophene-2,5-diyl) (P3HT) küçük kullanarak Birleşik ve ultra-küçük açı nötron saçılma varlığı ve yokluğu aydınlatma sunulur.

Aydınlatma nötron saçılma kullanarak konjuge polimer jelleri yapısını etkilerinin izlenmesi

We demonstrate a protocol to effectively monitor the gelation process of a high concentration solution of conjugated polymer both in the presence and ...

monitoring-effects-illumination-on-structure-conjugated-polymer-gels

Universidad de Cartagena UDEC

Research

JoVE Journal

Chemistry

5.6K Görüntüleme.  University of Tennessee, Knoxville. Bir iletişim kuralı Optoelektronik oluşan jelleri analizi için polimer poly(3-hexylthiophene-2,5-diyl) (P3HT) küçük kullanarak Birleşik ve ultra-küçük açı nötron saçılma varlığı ve yokluğu aydınlatma sunulur.

Video: Monitoring the Effects of Illumination on the Structure of Conjugated Polymer Gels Using Neutron Scattering

Using Neutron Spin Echo Resolved Grazing Incidence Scattering to Investigate Organic Solar Cell Materials

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped crystallites. Neutrons are passed through two well defined regions of magnetic field; one before and one after the sample. The two magnetic field regions have opposite polarity and are tuned such that neutrons travelling through both regions, without being perturbed, will undergo the same number of precessions in opposing directions. In this case the neutron precession in the second arm is said to &#34;echo&#34; the first, and the original polarization of the beam is preserved. If the neutron interacts with a sample and scatters elastically the path through the second arm is not the same as the first and the original polarization is not recovered. Depolarization of the neutron beam is a highly sensitive probe at very small angles (&#60;50&#160;&#956;rad) but still allows a high intensity, divergent beam to be used. The decrease in polarization of the beam reflected from the sample as compared to that from the reference sample can be directly related to structure within the sample.
In comparison to scattering observed in neutron reflection measurements the SERGIS signals are often weak and are unlikely to be observed if the in-plane structures within the sample under investigation are dilute, disordered, small in size and polydisperse or the neutron scattering contrast is low. Therefore, good results will most likely be obtained using the SERGIS technique if the sample being measured consist of thin films on a flat substrate and contain scattering features that contains a high density of moderately sized features (30 nm to 5 &#181;m) which scatter neutrons strongly or the features are arranged on a lattice. An advantage of the SERGIS technique is that it can probe structures in the plane of the sample.

Progress has been made in utilizing spin echo resolved grazing incidence scattering (SERGIS) as a neutron scattering technique to probe the length-scales in irregular samples. Crystallites of [6,6]-phenyl-C61-butyric acid methyl ester have been probed using the SERGIS technique and the results confirmed by optical and atomic force microscopy.

Nötron Spin Echo'nun Kullanılması, Organik Güneş Hücresi Malzemelerini Araştırmak İçin Otlatma İnsidansını Dağıtmayı Çözdü

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped ...

Mühendislik

Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus have potential applications in nonlinear optics, which requires extraordinary optical intensity. One of the most studied nonlinearities in plasmonics is nonlinear absorption, including saturation and reverse saturation behaviors. Although scattering and absorption in nanoparticles are closely correlated by the Mie theory, there has been no report of nonlinearities in plasmonic scattering until very recently. 
Last year, not only saturation, but also reverse saturation of scattering in an isolated plasmonic particle was demonstrated for the first time. The results showed that saturable scattering exhibits clear wavelength dependence, which seems to be directly linked to the localized surface plasmon resonance (LSPR). Combined with the intensity-dependent measurements, the results suggest the possibility of a common mechanism underlying the nonlinear behaviors of scattering and absorption. These nonlinearities of scattering from a single gold nanosphere (GNS) are widely applicable, including in super-resolution microscopy and optical switches. 
In this paper, it is described in detail how to measure nonlinearity of scattering in a single GNP and how to employ the super-resolution technique to enhance the optical imaging resolution based on saturable scattering. This discovery features the first super-resolution microscopy based on nonlinear scattering, which is a novel non-bleaching contrast method that can achieve a resolution as low as l/8 and will potentially be useful in biomedicine and material studies.

Saturable and reverse saturable scattering were discovered in isolated plasmonic particles and adopted as a novel non-bleaching contrast method in super-resolution microscopy. Here the experimental procedures of detecting and extracting nonlinear scattering are explained in detail, as well as how to enhance resolution with the aid of saturated excitation microscopy.

Tek plasmonik Nanoparçacığı gelen doğrusal olmayan Saçılma Ölçülmesi

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

Supramoleküler Kolloidlerin Sentezi ve Karakterizasyonu

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Kimya

Controlled Synthesis and Fluorescence Tracking of Highly Uniform Poly(N-isopropylacrylamide) Microgels

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this work, we use single particle tracking of fluorescently labeled PNIPAM microgels as a showcase for tuning microgel size by a rapid non-stirred precipitation polymerization procedure. This approach is well suited for prototyping new reaction compositions and conditions or for applications that do not require large amounts of product. Microgel synthesis, particle size and structure determination by dynamic and static light scattering are detailed in the protocol. It is shown that the addition of functional comonomers can have a large influence on the particle nucleation and structure. Single particle tracking by wide-field fluorescence microscopy allows for an investigation of the diffusion of labeled tracer microgels in a concentrated matrix of non-labeled microgels, a system not easily investigated by other methods such as dynamic light scattering.

Controlled Synthesis and Fluorescence Tracking of Highly Uniform PolyN-isopropylacrylamide Microgels

Non-stirred precipitation polymerization provides a rapid, reproducible prototyping approach to the synthesis of stimuli-sensitive poly(N-isopropylacrylamide) microgels of narrow size distribution. In this protocol synthesis, light scattering characterization and single particle fluorescence tracking of these microgels in a wide-field microscopy setup are demonstrated.

Kontrollü Sentezi ve yüksek Düzgün Poli Floresan Takibi (<em&gt; K</em&gt; -isopropylacrylamide) Mikrojeller

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this ...

Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise composition of these materials is essential, especially in the design of surface catalysts, where the surface concentration of the active component determines the activity of the material. Antimicrobial materials which utilize nanoparticles are a particular focus of this technology. Recently swell encapsulation has emerged as a technique for inserting antimicrobial nanoparticles into a host polymer matrix. Swell encapsulation provides the advantage of localizing the incorporation to the external surfaces of materials, which act as the active sites of these materials. However, quantification of this nanoparticle uptake is challenging. Previous studies explore the link between antimicrobial activity and surface concentration of the active component, but this is not directly visualized. Here we show a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of CdSe/ZnS nanoparticles can be accurately visualized through cross-sectional fluorescence imaging. Using this method, we can quantify the uptake of nanoparticles via swell encapsulation and measure the surface concentration of encapsulated particles, which is key in optimizing the activity of functional materials.

Here we present a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of cadmium selenide quantum dots can be accurately visualized through cross-sectional fluorescence imaging.

Doğrudan Floresan Görüntüleme kullanma Nanoparçacık-polimer kompozitler Gelişmiş Bileşim Analizi

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise ...

Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a technique used to measure the size distribution of polymer solutions or colloidal particles. Although this technique is widely used for the assessment of polymer solutions, it is difficult to measure the particle size in concentrated solutions due to the multiple scattering effect or strong light absorption. Therefore, the concentrated solutions should be diluted before measurement. Implementation of the confocal optical component in a dynamic light scattering microscope1 helps to overcome this barrier. Using such a microscopic system, both transparent and turbid systems can be analyzed under the same experimental setup without a dilution. As a representative example, a size distribution measurement of a temperature-responsive polymer solution was performed. The sizes of the polymer chains in an aqueous solution were several tens of nanometers at a temperature below the lower critical solution temperature (LCST). In contrast, the sizes increased to more than 1.0 &#181;m when above the LCST. This result is consistent with the observation that the solution turned turbid above the LCST.

A protocol for the direct measurement of particle size distribution in concentrated solutions using dynamic light scattering microscopy is presented.

Dinamik ışık saçılımı Mikroskopi Bulanık Çözümleri Tane Büyüklüğü Dağılımının Ölçümü

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a ...

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

We discuss in this article the experimental measurements of the molecules in liquid crystal (LC) phase using the time-resolved infrared (IR) vibrational spectroscopy and time-resolved electron diffraction. Liquid crystal phase is an important state of matter that exists between the solid and liquid phases and it is common in natural systems as well as in organic electronics. Liquid crystals are orientationally ordered but loosely packed, and therefore, the internal conformations and alignments of the molecular components of LCs can be modified by external stimuli. Although advanced time-resolved diffraction techniques have revealed picosecond-scale molecular dynamics of single crystals and polycrystals, direct observations of packing structures and ultrafast dynamics of soft materials have been hampered by blurry diffraction patterns. Here, we report time-resolved IR vibrational spectroscopy and electron diffractometry to acquire ultrafast snapshots of a columnar LC material bearing a photoactive core moiety. Differential-detection analyses of the combination of time-resolved IR vibrational spectroscopy and electron diffraction are powerful tools for characterizing structures and photoinduced dynamics of soft materials.

Here, we present the protocols of differential-detection analyses of time-resolved infrared vibrational spectroscopy and electron diffraction which enable observations of the deformations of local structures around photoexcited molecules in a columnar liquid crystal, giving an atomic perspective on the relationship between the structure and the dynamics of this photoactive material.

Yapısal Photoresponsive sıvı kristaller dinamikleri gözlemlemek için yeni teknikleri

We discuss in this article the experimental measurements of the molecules in liquid crystal (LC) phase using the time-resolved infrared (IR) vibrational ...

Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization

We report a method to generate the N-heterocyclic carbene (NHC) 1,3-dimesitylimidazol-2-ylidene (IMes) under UV-irradiation at 365 nm to characterize IMes and determine the corresponding photochemical mechanism. Then, we describe a protocol to perform ring-opening metathesis polymerization (ROMP) in solution and in miniemulsion using this NHC-photogenerating system. To photogenerate IMes, a system comprising 2-isopropylthioxanthone (ITX) as the sensitizer and 1,3-dimesitylimidazolium tetraphenylborate (IMesH+BPh4-) as the protected form of NHC is employed. IMesH+BPh4- can be obtained in a single step by anion exchange between 1,3-dimesitylimidazolium chloride and sodium tetraphenylborate. A real-time steady-state photolysis setup is described, which hints that the photochemical reaction proceeds in two consecutive steps: 1) ITX triplet is photo-reduced by the borate anion and 2) subsequent proton transfer takes place from the imidazolium cation to produce the expected NHC IMes. Two separate characterization protocols are implemented. Firstly, CS2 is added to the reaction media to evidence the photogeneration of NHC through formation of the IMes-CS2 adduct. Secondly, the amount of NHC released in situ is quantified using acid-base titration. The use of this NHC photo-generating system for the ROMP of norbornene is also discussed. In solution, a photopolymerization experiment is conducted by mixing ITX, IMesH+BPh4-, [RuCl2(p-cymene)]2 and norbornene in CH2Cl2, then irradiating the solution in a UV reactor. In a dispersed medium, a monomer miniemulsion is first formed then irradiated inside an annular reactor to produce a stable poly(norbornene) latex.

We describe a protocol to photogenerate N-heterocyclic carbenes (NHCs) by UV irradiation of a 2-isopropylthioxanthone/imidazolium tetraphenylborate salt system. Methods to characterize the photoreleased NHC and elucidate the photochemical mechanism are proposed. The protocols for ring-opening metathesis photopolymerization in solution and miniemulsion illustrate the potential of this 2-component NHC photogenerating system.

N oluşur Carbenes Photogeneration: Photoinduced yüzük-açılış sentezde polimerizasyon uygulamada

We report a method to generate the N-heterocyclic carbene (NHC) 1,3-dimesitylimidazol-2-ylidene (IMes) under UV-irradiation at 365 nm to characterize IMes ...

Light-mediated Formation and Patterning of Hydrogels for Cell Culture Applications

Click chemistries have been investigated for use in numerous biomaterials applications, including drug delivery, tissue engineering, and cell culture. In particular, light-mediated click reactions, such as photoinitiated thiol&#8722;ene and thiol&#8722;yne reactions, afford spatiotemporal control over material properties and allow the design of systems with a high degree of user-directed property control. Fabrication and modification of hydrogel-based biomaterials using the precision afforded by light and the versatility offered by these thiol&#8722;X photoclick chemistries are of growing interest, particularly for the culture of cells within well-defined, biomimetic microenvironments. Here, we describe methods for the photoencapsulation of cells and subsequent photopatterning of biochemical cues within hydrogel matrices using versatile and modular building blocks polymerized by a thiol&#8722;ene photoclick reaction. Specifically, an approach is presented for constructing hydrogels from allyloxycarbonyl (Alloc)-functionalized peptide crosslinks and pendant peptide moieties and thiol-functionalized poly(ethylene glycol) (PEG) that rapidly polymerize in the presence of lithium acylphosphinate photoinitiator and cytocompatible doses of long wavelength ultraviolet (UV) light. Facile techniques to visualize photopatterning and quantify the concentration of peptides added are described. Additionally, methods are established for encapsulating cells, specifically human mesenchymal stem cells, and determining their viability and activity. While the formation and initial patterning of thiol-alloc hydrogels are shown here, these techniques broadly may be applied to a number of other light and radical-initiated material systems (e.g., thiol-norbornene, thiol-acrylate) to generate patterned substrates.

We describe a sequential process for light-mediated formation and subsequent biochemical patterning of synthetic hydrogel matrices for three-dimensional cell culture applications. The construction and modification of hydrogels with cytocompatible photoclick chemistry is demonstrated. Additionally, facile techniques to quantify and observe patterns and determine cell viability within these hydrogels are presented.

Hücre Kültürü Uygulamaları için Hidrojeller Işık aracılı Oluşumu ve Desenlendirme

Click chemistries have been investigated for use in numerous biomaterials applications, including drug delivery, tissue engineering, and cell culture. In ...

Biyomühendislik

Measuring the Time-Evolution of Nanoscale Materials with Stopped-Flow and Small-Angle Neutron Scattering

This paper presents the use of a stopped-flow small-angle neutron-scattering (SANS) sample environment to quickly mix liquid samples and study nanoscale kinetic processes on time scales of seconds to minutes. The stopped-flow sample environment uses commercially available syringe pumps to mix the desired volumes of liquid samples that are then injected through a dynamic mixer into a quartz glass cell in approximately 1 s. Time-resolved SANS data acquisition is synced with the sample mixing to follow the evolution of the nanostructure in solution after mixing. 
To make the most efficient use of neutron beam time, we use a series of flow selector valves to automatically load, rinse, and dry the cell between measurements, allowing for repeated data collection throughout multiple sample injections. Sample injections are repeated until sufficient neutron scattering statistics are collected. The mixing setup can be programmed to systematically vary conditions to measure the kinetics at different mixing ratios, sample concentrations, additive concentrations, and temperatures. The minimum sample volume required per injection is approximately 150 &#181;L depending on the path length of the quartz cell. 
Representative results using this stopped-flow sample environment are presented for rapid lipid exchange kinetics in the presence of an additive, cyclodextrin. The vesicles exchange outer-leaflet (exterior) lipids on the order of seconds and fully exchange both interior and exterior lipids within hours. Measuring lipid exchange kinetics requires in situ mixing to capture the faster (seconds) and slower (minutes) processes and extract the kinetic rate constants. The same sample environment can also be used to probe molecular exchange in other types of liquid samples such as lipid nanoparticles, proteins, surfactants, polymers, emulsions, or inorganic nanoparticles. Measuring the nanoscale structural transformations and kinetics of exchanging or reacting systems will provide new insights into processes that evolve at the nanoscale.

This protocol presents the use of a stopped-flow sample environment to quickly mix multiple liquid solutions in situ during a small-angle neutron scattering measurement and to study kinetic processes on nanometer length scales and second time scales.

Nano Ölçekli Malzemelerin Zaman-Evrimini Durdurulmuş Akış ve Küçük Açılı Nötron Saçılması ile Ölçme

This paper presents the use of a stopped-flow small-angle neutron-scattering (SANS) sample environment to quickly mix liquid samples and study nanoscale ...