Questo lavoro è stato sostenuto in parte da KAKENHI (25708020, 15K13812, 15H00860, 15H00986, 16H02081) dal JSPS / MEXT Japan, dalla Fondazione Asahi Glass e dall&#39;iniziativa pre-strategica dell&#39;Università di Tsukuba, &quot;Ensemble della luce con le questioni e la vita&quot;.

1. Protocolli di fabbricazione di microsfere di polimeri <ol><li> Metodo di diffusione del vapore <ol><li> Sciogliere 2 mg di polimeri coniugati come P1 (poli [(9,9-dioctilfluorene-2,7-diil) - alt- (5-ottiltieno [3,4- c ] pirrolo-4,6-dione- 3-diil)) 28 e P2 (poli [(N- (2-eptilundecil) carbazolo-2,7-diil) - alt- (4,8-bis [(dodecil) carbonil] benzo [1,2- : 4,5- b &#39;] ditiofene-2,6-diil)] 28 , in 2 ml di cloroformio (un buon solvente) in una fiala da 5 ml. </li><li> Mettere 5 mL di metanolo (un povero solvente) in una fiala di 50 mL. </li><li> Inserire il flaconcino da 5 ml contenente la soluzione cloroformica del polimero nel flaconcino da 50 ml contenente metanolo. </li><li> Fissare il flaconcino da 50 ml e tenerlo per 3 giorni a 25 ° C per consentire la precipitazione delle microsfere del polimero. </li></ol></li><li> Metodo di mini-emulsione <ol><li> Sciogliere 5 mg di polimeri coniugati, come polY [9,9-di-n-ottilfluorenil-2,7-diil] (PFO) e poli [2-metossi-5- (3 &#39;, 7&#39;-dimetilattilossi) -1,4-fenilenvinilen] (MDMOPPV) In 1 mL di cloroformio. </li><li> Sciogliere 30 mg (~ 50 mM) di dodecil solfato di sodio (SDS) in 2 ml di acqua deionizzata. </li><li> Aggiungere 100 μL della soluzione cloroformica del polimero a 2 ml di acqua contenente SDS. </li><li> Mescolare vigorosamente la miscela di cloroformio / acqua usando un omogenizzatore ultra veloce a 30.000 giri / min per 2 minuti per emulsionare la soluzione. </li><li> Conservare per 1 giorno senza soffiare il flaconcino per evaporare il cloroformio. </li><li> Centrifugare la dispersione in un tubo di microcentrifuga da 1,5 ml per 5 min a 2.200 x g. Rimuovere la soluzione acquosa di supernatante contenente SDS. </li><li> Aggiungere 2 ml di acqua deionizzata e agitare energicamente. </li><li> Ripetere la fase 1.2.6 e 1.2.7 tre volte per lavare la SDS residua. </li></ol></li><li> Metodo di precipitazione dell&#39;interfaccia </li><li> Sciogliere 200 μg di polistirene (PS) e 10 μG di colorante fluorescente (dipirreno di boro, BODIPY) a 0,2 mL di tetraidrofurano (THF). </li><li> Versare delicatamente la soluzione di THF su 1 ml dello strato d&#39;acqua. </li><li> Conservare il THF / acqua separato a due strati per 6 ore senza coperchio della fiala per consentire la precipitazione delle microsfere del polimero. </li></ol> 2. Misurazione micro-fotoluminescenza (μ-PL) <ol><li> Preparazione del campione <ol><li> Diluire una sospensione delle microsfere preparate nella sezione 1 in una soluzione non solvente ( ossia metanolo o acqua deionizzata). </li><li> Spin-cast una goccia (20-30 μL) della sospensione diluita delle microsfere su un substrato di quarzo usando uno spin-coater (tipicamente 2.000 giri / min per 50 s). </li><li> Asciugare in aria la pellicola di colata risultante finché i solventi non sono completamente evaporati (~ 5 min). </li></ol></li><li> Setup sperimentale <ol><li> Mettere il substrato di quarzo (15 x 15 x 0,5 mm 3 ) sulla fase di campionamento di un micr. Otticooscope. </li><li> Trova microsfere ben definite che sono isolate da altre sfere e adatte alla misura μ-PL. </li><li> Selezionare un laser ( cioè lunghezza d&#39;onda, onda continua o impulso, tempo di irradiazione, integrazione, ecc. ). </li><li> Selezionare l&#39;ingrandimento dell&#39;obiettivo. </li></ol></li><li> misure <ol><li> Utilizzare un fascio laser concentrato per irradiare la microsfera. Utilizzare la seguente condizione laser: cw o laser pulsato con lunghezze d&#39;onda di eccitazione ( λ ex ) di 405 nm (cw), 450 nm (cw), 355 nm (laser a impulsi, frequenza 1 kHz, durata dell&#39;impulso, 7 ns) e 470 Nm (laser a impulsi, frequenza, 2,5 MHz, durata dell&#39;impulso, 70 ps). </li><li> Registrare lo spettro PL sul punto eccitato usando uno spettrometro con una griglia di 300 o 1.200 scanalature mm -1 . </li><li> Prendi un&#39;immagine fluorescente. </li><li> Cambiare il punto di eccitazione spostando lo stadio di campionamento. </li><li> Cambiare il punto di rilevamento inclinando il collimatore(se necessario). </li></ol></li></ol> 3. Tecnica di micromanipolazione <ol><li> Manipolazione di microsfere <ol><li> Impostare un substrato di quarzo su cui le microsfere sono immobilizzate sulla fase di campionamento di un microscopio ottico. </li><li> Trovare una microsfera ben definita appropriata per la misura μ-PL. </li><li> Impostare un micro-ago in plastica su un dispositivo di micro-manipolazione. </li><li> Spostare il microsago utilizzando un joystick controllato dal computer per raccogliere una microsfera. </li><li> Spostare la microsfera e collegarlo ad un&#39;altra microsfera. </li><li> Misurare μ-PL dalla microsfera collegata. </li></ol></li></ol>

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The selection of a good solvent and non-solvent is very important for the self-assembly of well-defined microspheres. If the solubility of a polymer is too high, precipitation will not occur. Also, in general, &#960;-conjugated polymers are hydrophobic, so polar non-solvents, such as MeOH, acetonitrile, and acetone, are often used in the vapor diffusion method to minimize the surface energy required to form a spherical shape. The interface precipitation method is often adopted for the preparation of dye-doped polymer microspheres. Non-conjugated polymers, such as polystyrene, poly(methylmethacrylate), and poly(dimethylsiloxane), are often used as the sphere medium. These polymers are less hydrophobic than typical &#960;-conjugated polymers, so heavy agglomeration does not occur after precipitation in water. If microspheres are not obtained using these methods, other methods, such as post-polymerization dispersion and emulsion polymerization, can be adopted33.
The crystallinity of polymers is the important factor. Generally, &#960;-conjugated polymers have a flat, &#960;-electronic plane. Thus, &#960;-stacking results in the crystallization of the polymers, which prevents the isotropic growth of spheres. Hence, polymers with highly twisted &#960;-electronic planes are favorable for the formation of well-defined microspheres, which prevents interchain &#960;-stacking and amorphous aggregation. To prepare microspheres from polymers with high crystallinity, the mini-emulsion method is appropriate. However, for this method, the surface morphology of the resultant spheres is not very smooth because of the coverage of the surfactant. 
The preferred method of observing WGM PL is to use a focused laser beam to irradiate the rim of a microsphere. The contact point with the substrate causes a defect in the microsphere where the confined light leaks. Therefore, when a focused laser is used to irradiate a microsphere, all the confined light passes through the contact point with the substrate. On the other hand, when the rim of the microsphere is excited, most routes of the confined light do not pass through the contact point with the substrate, leading to better confinement. Thus, well-defined, high-Q WGM PL lines appear.
To conduct WGM lasing from conjugated polymer microspheres, several conditions are required: [1] For the population inversion, high-density optical pumping is needed by using, for example, a femto-second laser pulse. [2] Polymers must hardly be photodamaged upon strong photoexcitation. [3] Highly dispersed microspheres with smooth surfaces are preferred. If these conditions are satisfied, WGM lasing properties can be observed from conjugated polymer microsphere resonators. Fluorescent dye-doped polymer microspheres are also applicable to chemical and biological sensing tools and can be used for laser and optical circuit applications34,35.

Le particelle di nano polimero / micro-dimensioni sono ampiamente utilizzate per una varietà di applicazioni, tra cui supporto per catalizzatore, riempitivi di cromatografia a colonna, agenti di somministrazione di farmaci, sonde fluorescenti per il monitoraggio delle celle, supporti ottici e così via 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 . In particolare, i polimeri π-coniugati presentano proprietà intrinseche luminescenti e di carica che beneficiano di applicazioni ottiche, elettroniche e optoelettroniche usando sfere polimeriche 10 , 11 , 12 , 13 , 14 , in particolare applicazioni laser usando organi softMateriali anici 15 , 16 , 17 . Ad esempio, l&#39;integrazione tridimensionale di sfere con centinaia di diametri di nanometro forma cristalli colloidali, che mostrano lacune di banda fotonica ad una determinata lunghezza d&#39;onda 18 , 19 . Quando la luce è confinata nella struttura periodica dell&#39;interscono, l&#39;azione di lucentezza appare al centro della fascia di arresto. D&#39;altra parte, quando le dimensioni delle sfere aumentano alla scala multi-micrometrica, la luce è confinata all&#39;interno di un&#39;unica microsfera attraverso la riflessione interna totale all&#39;interfaccia polimero / aria 20 . La propagazione dell&#39;onda di luce alla circonferenza massima provoca interferenze, portando alla comparsa di una modalità risonante con linee di emissione nitide e periodiche. Queste modalità ottiche sono le cosiddette &quot;modalità gallerie sussurrate&quot; (WGMs). Il termine &quot;sussurra la galleria&quot; ha origine daCattedrale di St. Paul a Londra, dove le onde sonore si propagano lungo la circonferenza del muro, permettendo di sentire gli sussurri da una persona dall&#39;altra parte della galleria. Poiché la lunghezza d&#39;onda della luce è sulla scala sub-micrometra, che è molto più piccola delle onde sonore, una grande cupola non è necessaria per il WGM della luce: piccole navi micrometriche e ben definite, come microsfere, microdisc , E microcristalli, soddisfano le condizioni WGM. L&#39;equazione 1 è una forma semplice della condizione risonante WGM 21 : Nπd = lλ (1) Dove n è l&#39;indice di rifrazione del risonatore, d è il diametro, l è il numero intero e λ è la lunghezza d&#39;onda della luce. La parte sinistra di (1) è la lunghezza del percorso ottico attraverso una propagazione di cerchio. Quando il percorso ottico coincide con ilIntero multiplo della lunghezza d&#39;onda, si verifica una risonanza, mentre all&#39;altra lunghezza d&#39;onda l&#39;onda di luce si riduce all&#39;arrotondamento. Questo documento introduce diversi metodi sperimentali per preparare microsfere per i risonatori WGM da polimeri coniugati in soluzione: diffusione del vapore 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , mini-emulsione 31 e precipitazione d&#39;interfaccia 32 . Ogni metodo ha caratteristiche uniche; Per esempio, il metodo di diffusione del vapore fornisce microsfere ben definite con sfericità molto elevata e superfici lisce, ma solo polimeri a bassa cristallinità possono formare queste microsfere. D&#39;altra parte, per la mini-emulsioneMetodo, diversi tipi di polimeri coniugati, compresi i polimeri ad alta cristallina, possono formare sfere, ma la morfologia superficiale è inferiore a quella ottenuta dal metodo di diffusione del vapore. Il metodo di precipitazione dell&#39;interfaccia è preferibile per la creazione di microsfere di polimeri non coniugati con coloranti. In tutti i casi, la selezione del solvente e del non solvente svolge un ruolo importante nella formazione della morfologia sferica. Nella seconda metà di questo documento sono state presentate tecniche μ-PL e micro-manipolazione. Per la tecnica μ-PL, le microsfere sono disperse su un substrato e un fascio laser concentrato, tramite un obiettivo microscopico, viene utilizzato per irradiare una singola microsfera isolata 24 . Il PL generato da una sfera viene rilevato da uno spettrometro attraverso l&#39;obiettivo del microscopio. Lo spostamento della fase di campionamento può variare la posizione del punto di eccitazione. Il punto di rilevamento è anche variabile inclinando l&#39;ottica del collimatore dell&#39;exciFascio laser rispetto all&#39;asse ottico del percorso di rilevazione 28 , 32 . Per studiare la propagazione della luce intersferale e la conversione della lunghezza d&#39;onda, è possibile utilizzare la tecnica di micro-manipolazione 32 . Per collegare diverse microsfere con differenti proprietà ottiche, è possibile prelevare una sfera usando un microsago e posizionandolo su un&#39;altra sfera. In combinazione con le tecniche di micromanipolazione e il metodo μ-PL, possono essere eseguite varie misurazioni ottiche usando sfere polimeriche coniugate, che vengono preparate con un semplice metodo di autoassemblaggio. Questa carta video sarà utile ai lettori che desiderano utilizzare materiali polimerici morbidi per applicazioni ottiche.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>polystyrene</td>
			<td>Aldrich</td>
			<td>132427-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>sodium dodecylsulfate</td>
			<td>Kanto Kagaku</td>
			<td>372035-31</td>
			<td></td>
		</tr>
		<tr>
			<td>tetrahydrofuran</td>
			<td>Wako</td>
			<td>206-08744</td>
			<td></td>
		</tr>
		<tr>
			<td>chloroform</td>
			<td>Wako</td>
			<td>038-18495</td>
			<td></td>
		</tr>
		<tr>
			<td>methanol</td>
			<td>Wako</td>
			<td>139-13995</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly(9,9-di-n-octylfluorenyl-2,7-diyl)</td>
			<td>Aldrich</td>
			<td>571652-500MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly[2-methoxy-5-(3&#8242;,7&#8242;-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMOPPV)</td>
			<td>Aldrich</td>
			<td>546461-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>poly[(9,9-dioctylfluorene-2,7-diyl)-alt-(5-octylthieno[3,4-c]pyrrole-4,6-dione-1,3-diyl)] (P1)</td>
			<td>synthesized</td>
			<td>-</td>
			<td>reference 28</td>
		</tr>
		<tr>
			<td>poly[(N-(2-heptylundecyl)carbazole-2,7-diyl)-alt-(4,8-bis[(dodecyl)carbonyl]benzo[1,2-b:4,5-b&#8242;]dithiophene-2,6-diyl)] (P2)</td>
			<td>synthesized</td>
			<td>-</td>
			<td>reference 28</td>
		</tr>
		<tr>
			<td>fluorescent dye (boron dipyrrin; BODIPY)</td>
			<td>synthesized</td>
			<td>-</td>
			<td>reference 32</td>
		</tr>
		<tr>
			<td>Optical Microscope</td>
			<td>Nicon</td>
			<td>Eclipse LV-N</td>
			<td></td>
		</tr>
		<tr>
			<td>laser_405 nm</td>
			<td>Hutech</td>
			<td>DH405-10-5</td>
			<td></td>
		</tr>
		<tr>
			<td>laser_355 nm</td>
			<td>CNI</td>
			<td>MPL-F-355-10&#65357;W</td>
			<td></td>
		</tr>
		<tr>
			<td>Spectrometer</td>
			<td>Lambda Vision</td>
			<td>LV-MC3/T</td>
			<td></td>
		</tr>
		<tr>
			<td>Homogenizer</td>
			<td>Microtech Nichion</td>
			<td>Physcotron NS-360D</td>
			<td></td>
		</tr>
		<tr>
			<td>micromanipulation</td>
			<td>Microsupport</td>
			<td>Quick Pro QP-3RH</td>
			<td></td>
		</tr>
	</tbody>
</table>

fabrication of polymer microspheres for optical resonator and laser applications

Questo articolo descrive tre metodi per la preparazione di microsfere fluorescenti che comprendono polimeri π-coniugati o non coniugati: diffusione del vapore, precipitazione dell&#39;interfaccia e mini-emulsione. In tutti i metodi, le sfere di dimensioni micrometriche ben definite sono ottenute da un processo di auto-assemblaggio in soluzione. Il metodo di diffusione del vapore può provocare sfere con la più alta sfericità e superficie liscia, tuttavia i tipi di polimeri in grado di formare queste sfere sono limitate. D&#39;altra parte, nel metodo di mini-emulsione, le microsfere possono essere fatte da vari tipi di polimeri, anche da polimeri altamente cristallini con coplanari, π-coniugati spine. Le proprietà fotoluminescenti (PL) da singole microsfere isolate sono inusuali: il PL è confinato all&#39;interno delle sfere, si propaga alla circonferenza delle sfere attraverso la riflessione interna totale all&#39;interfaccia polimero / aria e si auto-interferisce per mostrare una resonante forte e periodica Linee PL. Questi resonatiLe modalità g sono le cosiddette &quot;modalità gallerie sussurrate&quot; (WGMs). Questo lavoro illustra come misurare WGM PL da singole sfere isolate utilizzando la tecnica della micro-fotoluminescenza (μ-PL). In questa tecnica, un raggio laser concentrato irradia un&#39;unica microsfera, e la luminescenza viene rilevata da uno spettrometro. Una tecnica di micromanipolazione viene quindi usata per collegare le microsfere una per una e per dimostrare la propagazione PL e la conversione del colore da microsfere accoppiate su eccitazione al perimetro di una sfera e rilevazione di PL dall&#39;altra microsfera. Queste tecniche, μ-PL e micromanipolazione, sono utili per gli esperimenti sull&#39;applicazione micro-ottica utilizzando materiali polimerici.

La figura 1 mostra le rappresentazioni schematiche del metodo di diffusione del vapore (a), del metodo di mini-emulsione (b) e del metodo di precipitazione dell&#39;interfaccia (c). Per il metodo di diffusione del vapore ( Figura 1a ), un flaconcino da 5 mL contenente una soluzione CHCl3 di polimeri (0,5 mg mL -1 , 2 mL) è stato posto in un flaconcino da 50 mL contenente 5 mL di un non solvente, come MeOH . Il flaconcino esterno è stato ricoperto e poi lasciato per 3 giorni a 25 ° C. Il vapore del non solvente si diffuse lentamente nella soluzione, con conseguente precipitazione dei polimeri attraverso lo stato supersaturo. Per il metodo di mini-emulsione ( figura 1b ), una soluzione CHCl3 di polimeri (5 mg mL -1 , 200 μL) è stata aggiunta a una soluzione acquosa di sodio n- dodecil solfato (SDS, 1 mM, 2 mL). La soluzione separata a due fasi di acqua / CHCl3 è stata emulsaMescolando con un omogeneizzatore (30.000 giri / min, 5 min). L&#39;emulsione risultante è stata lasciata per 24 ore a 25 ° C e 1 atm per evaporare naturalmente il CHCl3. L&#39;eccesso di SDS è stato rimosso scambiando l&#39;acqua supernatante mediante centrifugazione (3 volte) per ottenere un precipitato di polimeri coniugati. Per il metodo di precipitazione dell&#39;interfaccia ( figura 1c ), una soluzione di THF di una miscela di polistirene (PS, [PS] = 1,0 mg mL -1 ) e colorante fluorescente ([dye] = 0,002-1,0 mg mL -1 = 6,4-3,200 ΜM) è stato accuratamente aggiunto allo strato non solvente di una miscela acqua / EtOH (6/1 v / v, 1 mL). La diffusione lenta dei solventi, insieme all&#39;evaporazione simultanea di THF in aria, ha portato alla precipitazione dopo 6 ore di invecchiamento. Microscopi di scansione microscopica elettronica (SEM) delle microsfere ottenute da ciascun metodo vengono visualizzate in FiguraUre 1. Per le tecniche di diffusione del vapore e di precipitazione dell&#39;interfaccia, sono state ottenute microsfere ben definite con elevata sfericità e superfici lisce. D&#39;altra parte, per il metodo di mini-emulsione, sono state ottenute microsfere ben definite, ma la morfologia superficiale non era così liscia rispetto a quella prodotta dagli altri metodi. Questo perché il tensioattivo copre tutta la superficie delle microsfere. Tuttavia, il merito del metodo di mini-emulsione è che le microsfere possono essere fatte da vari tipi di polimeri coniugati. Questo è abbastanza vantaggioso perché, con il metodo di diffusione del vapore, i polimeri con elevata cristallinità non costituiscono quasi geometria sferica. Nel metodo di precipitazione dell&#39;interfaccia, l&#39;acqua viene spesso utilizzata come non solvente sullo strato inferiore. Tuttavia, i polimeri π-coniugati sono di solito molto idrofobi, pertanto si verificano agglomerati pesanti delle microsfere risultanti. Questo è svantaggioso per isolare ogni singola microsfera su un substrato per μ-PL measurements. La figura 2 mostra una rappresentazione schematica della configurazione sperimentale μ-PL. Un microscopio ottico con un obiettivo 50X o 100X è stato utilizzato per identificare le particelle adatte e per determinare i loro diametri ( d ). Per le misurazioni è stato utilizzato un sistema μ-PL con un microscopio combinato con un monochromatore (griglia: 300 o 1.200 scanalature mm -1 ) e una telecamera CCD. Il perimetro di una singola microsfera è stato fotografato a 25 ° C in condizioni ambientali da un laser cw o pulsato con una lunghezza d&#39;onda di eccitazione ( λ ex ) di 405 nm (cw), 532 nm (cw), 355 nm (laser a impulsi, frequenza, 1 kHz, durata dell&#39;impulso, 7 ns) o 470 nm (laser a impulsi, frequenza, 2,5 MHz, durata dell&#39;impulso, 70 ps). Per le misurazioni μ-PL con diverse posizioni di eccitazione e di rilevamento, le sfere sono state eccitate da un laser da 405 nm,E la luce è stata raccolta in confocal setup da un obiettivo 50X e rilevata da uno spettrometro con una griglia da mm 300 di groove. La dimensione del punto, il potere laser e il tempo di integrazione erano rispettivamente 0,5 μm, 0,5 μW e 1 s. Per separare il punto di rilevamento dall&#39;eccitazione, l&#39;ottica del collimatore del raggio laser di eccitazione è stata inclinata rispetto all&#39;asse ottico del percorso di rilevamento. La figura 3 mostra il PL WGM di una singola microsfera di polimeri π-coniugati: P1 16k , P2 e le loro miscele. 28 Spettri spettrali WGM PL sono stati osservati da tutte le singole microsfere. Il fattore Q, definito da una picco di lunghezza d&#39;onda divisa per la mezza larghezza del picco, ha raggiunto fino a 2.200 per le microsfere di P1 16k , mentre le microsfere di P2 hanno mostrato un fattore Q di soli 300, possibilmenteY per la morfologia della superficie ruvida 28 . Per le microsfere di miscela polimerica si è verificato un efficiente trasferimento di energia dell&#39;intrasfera, con conseguente spostamento significativo del WGM PL da una regione gialla a quella rossa. Un elevato fattore Q (1.500) è stato mantenuto a causa della superficie liscia. Inoltre, la cascata di trasferimento di energia dell&#39;intersconda è stata studiata da una combinazione di tecniche di micro-manipolazione e μ-PL. Pertanto, le microsfere PS di tipo bimbo-polimero polimorfico (BODIPY) con colori PL di verde, giallo, arancio e rosso sono stati collegati uno a uno per formare tetrasfere con configurazioni lineari e a forma di T ( Figura 4 ) 32 . L&#39;analisi dettagliata dell&#39;efficienza del trasferimento energetico ha indicato che il trasferimento di energia dalla luce dal verde al giallo e dal giallo all&#39;arancio è avvenuto in modo efficiente, mentre il trasferimento di energia da arancione a rosso è stato difficile<html> Ecause della piccola sovrapposizione tra la banda PL del donatore di energia e la banda di assorbimento dell&#39;acceptore di energia. Inutile dire che i trasferimenti di energia convertiti, come il rosso all&#39;arancio, il giallo e il verde, non si sono verificati. <img alt="Figura 1" class="xfigimg" src="/files/ftp_upload/55934/55934fig1.jpg" /> Figura 1: Metodo di preparazione di microsfere di polimeri. Schemi rappresentativi del metodo di diffusione del vapore ( a ), metodo di mini-emulsione ( b ) e metodo di precipitazione dell&#39;interfaccia ( c ) e microscopi SEM delle microsfere polimeriche risultanti da ciascun metodo di preparazione. <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55934/55934fig1large.jpg" target="_blank">Clicca qui per visualizzare una versione più grande di questa figura.</a> 55934fig2.jpg &quot;/&gt; Figura 2: Rappresentazione schematica della configurazione sperimentale per le misurazioni μ-PL. <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55934/55934fig2large.jpg" target="_blank">Clicca qui per visualizzare una versione più grande di questa figura.</a> <img alt="Figura 3" class="xfigimg" src="/files/ftp_upload/55934/55934fig3.jpg" /> Figura 3: Spettri PL da un&#39;unica microsfera. ( A ) Strutture molecolari di P1 16k e P2 e rappresentazioni schematiche delle microsfere da P1 16k , P2 e della loro miscela ( P1 16k / P2 = 8/2 w / w), insieme ai loro micrografi SEM. ( B - d ) Spettri PL da un&#39;unica microsfera formata da P1 16k ( b ),<html> Miscela P1 16k / P2 ( c ) e P2 ( d ). <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55934/55934fig3large.jpg" target="_blank">Clicca qui per visualizzare una versione più grande di questa figura.</a> <img alt="Figura 4" class="xfigimg" src="/files/ftp_upload/55934/55934fig4.jpg" /> Figura 4: Tecnica di micromanipolazione per organizzare le microsfere. ( A ) Microscopio ottico di microsfere polimorfiche BODIPY-doped PS, manipolate da un sottile micro-ago. ( B e c ) Microscopi ottici (superiori) e fluorescenti (inferiori) delle microsfere collegate con configurazioni lineari ( b ) e T ( c ). ( D ) Rappresentazione schematica del trasferimento di energia intersferi a lungo termine mediata dalla cavità.Jpg &quot;target =&quot; _ blank &quot;&gt; Fare clic qui per visualizzare una versione più grande di questa figura.

Watch this Scientific Journal Video about Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications at JoVE.com

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

Sono presentati i protocolli per la sintesi di microsfere da polimeri, la manipolazione delle microsfere e le misure di micro-fotoluminescenza.

Fabbricazione di microsfere di polimeri per risonatore ottico e applicazioni laser

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, ...

fabrication-polymer-microspheres-for-optical-resonator-laser

Nanyang Technological University

Research

JoVE Journal

Engineering

13.9K Views.  University of Tsukuba.  Sono presentati i protocolli per la sintesi di microsfere da polimeri, la manipolazione delle microsfere e le misure di micro-fotoluminescenza. 

Video: Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

Construction and Testing of Coin Cells of Lithium Ion Batteries

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime. Lithium ion batteries have also been considered to be used in electric and hybrid vehicles1 or even electrical grid stabilization systems2. All these applications simulate a dramatic increase in the research and development of battery materials3-7, including new materials3,8, doping9, nanostructuring10-13, coatings or surface modifications14-17 and novel binders18. Consequently, an increasing number of physicists, chemists and materials scientists have recently ventured into this area. Coin cells are widely used in research laboratories to test new battery materials; even for the research and development that target large-scale and high-power applications, small coin cells are often used to test the capacities and rate capabilities of new materials in the initial stage. 
 In 2010, we started a National Science Foundation (NSF) sponsored research project to investigate the surface adsorption and disordering in battery materials (grant no. DMR-1006515). In the initial stage of this project, we have struggled to learn the techniques of assembling and testing coin cells, which cannot be achieved without numerous help of other researchers in other universities (through frequent calls, email exchanges and two site visits). Thus, we feel that it is beneficial to document, by both text and video, a protocol of assembling and testing a coin cell, which will help other new researchers in this field. This effort represents the "Broader Impact" activities of our NSF project, and it will also help to educate and inspire students.
In this video article, we document a protocol to assemble a CR2032 coin cell with a LiCoO2 working electrode, a Li counter electrode, and (the mostly commonly used) polyvinylidene fluoride (PVDF) binder. To ensure new learners to readily repeat the protocol, we keep the protocol as specific and explicit as we can. However, it is important to note that in specific research and development work, many parameters adopted here can be varied. First, one can make coin cells of different sizes and test the working electrode against a counter electrode other than Li. Second, the amounts of C black and binder added into the working electrodes are often varied to suit the particular purpose of research; for example, large amounts of C black or even inert powder were added to the working electrode to test the "intrinsic" performance of cathode materials14. Third, better binders (other than PVDF) have also developed and used18. Finally, other types of electrolytes (instead of LiPF6) can also be used; in fact, certain high-voltage electrode materials will require the uses of special electrolytes7.

A protocol to construct and test coin cells of lithium ion batteries is described. The specific procedures of making a working electrode, preparing a counter electrode, assembling a cell inside a glovebox and testing the cell are presented.

Costruzione e collaudo di Pile Batterie agli ioni di litio

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime.  Lithium ion ...

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Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas allows the deposition of metal oxides with tunable morphology, structure, density and stoichiometry by a proper control of the plasma plume expansion dynamics. Such versatility can be exploited to produce nanostructured films from compact and dense to nanoporous characterized by a hierarchical assembly of nano-sized clusters. In particular we describe the detailed methodology to fabricate two types of Al-doped ZnO (AZO) films as transparent electrodes in photovoltaic devices: 1) at low O2 pressure, compact films with electrical conductivity and optical transparency close to the state of the art transparent conducting oxides (TCO) can be deposited at room temperature, to be compatible with thermally sensitive materials such as polymers used in organic photovoltaics (OPVs); 2) highly light scattering hierarchical structures resembling a forest of nano-trees are produced at higher pressures. Such structures show high Haze factor (&gt;80%) and may be exploited to enhance the light trapping capability. The method here described for AZO films can be applied to other metal oxides relevant for technological applications such as TiO2, Al2O3, WO3 and Ag4O4.

We describe the experimental method to deposit nanostructured oxide thin films by nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas. By using this method Al-doped ZnO (AZO) films, from compact to hierarchically structured as nano-tree forests, can be deposited.

Fabbricazione di nano-ingegneria trasparenti Ossidi Conducting da Pulsed Laser Deposition

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

Fabrication and Characterization of Disordered Polymer Optical Fibers for Transverse Anderson Localization of Light

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed polymer optical fiber is composed of 80,000 strands of poly (methyl methacrylate) (PMMA) and polystyrene (PS) that are randomly mixed and drawn into a square cross section optical fiber with a side width of 250 &mu;m. Initially, each strand is 200 &mu;m in diameter and 8-inches long. During the mixing process of the original fiber strands, the fibers cross over each other; however, a large draw ratio guarantees that the refractive index profile is invariant along the length of the fiber for several tens of centimeters. The large refractive index difference of 0.1 between the disordered sites results in a small localized beam radius that is comparable to the beam radius of conventional optical fibers. The input light is launched from a standard single mode optical fiber using the butt-coupling method and the near-field output beam from the disordered fiber is imaged using a 40X objective and a CCD camera. The output beam diameter agrees well with the expected results from the numerical simulations. The disordered optical fiber presented in this work is the first device-level implementation of 2D Anderson localization, and can potentially be used for image transport and short-haul optical communication systems.

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. This microstructured fiber can transport a small localized beam with a radius that is comparable to the beam radius of conventional optical fibers.

Fabbricazione e caratterizzazione di polimeri disordinati fibre ottiche per la Trasversale localizzazione di Anderson di Luce

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed ...

Patterning via Optical Saturable Transitions - Fabrication and Characterization

This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical Saturable Transitions (POST). In this technique the chemical properties of organic photochromic molecules that undergo single-photon reactions are exploited, enabling rapid top-down nanopatterning over large areas at low light intensities, thereby, allowing for the circumvention of the far-field diffraction barrier.4 Simple, cost-effective, high throughput and resolution alternatives to nanopatterning are being explored, such as, two-photon polymerization5,6, beam pen lithography (BPL)7, scanning electron beam lithography (SEBL), and focused ion beam (FIB) patterning. However, multi-photon approaches require high light intensities, which limit their potential for high throughput and offer low image contrast. Although, electron and ion beam lithographic processes offer increased resolution, the serial nature of the process is limited to slow writing speeds, which also prevents patterning of features over large areas. Beam-pen lithography is an approach towards parallel near-field optical lithography. However, the gap between the source of the beam and the surface of the photoresist needs to be controlled extremely precisely for good pattern uniformity and this is very challenging to accomplish for large arrays of beams. Patterning via Optical Saturable Transitions (POST) is an alternative optical nanopatterning technique for patterning sub-wavelength features1-3. Since this technique uses single photons instead of electrons, it is extremely fast and does not require high light intensities1-3, opening the door to massive parallelization.

We report that the diffraction limit of conventional optical lithography can be overcome by exploiting the transitions of organic photochromic derivatives induced by their photoisomerization at low light intensities.1-3 This paper outlines our fabrication technique and two locking mechanisms, namely: dissolution of one photoisomer and electrochemical oxidation.

Patterning via ottici saturabili Transitions - fabbricazione e la caratterizzazione

This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical ...

Fabrication and Operation of a Nano-Optical Conveyor Belt

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological and physical sciences over the past few decades. The progress made in this field invites further study of even smaller systems and at a larger scale, with tools that could be distributed more easily and made more widely available. Unfortunately, the fundamental laws of diffraction limit the minimum size of the focal spot of a laser beam, which makes particles smaller than a half-wavelength in diameter hard to trap and generally prevents an operator from discriminating between particles which are closer together than one half-wavelength. This precludes the optical manipulation of many closely-spaced nanoparticles and&#160;limits the&#160;resolution of optical-mechanical systems. Furthermore, manipulation using focused beams requires beam-forming or steering optics, which can be very bulky and expensive. To address these limitations in the system scalability of conventional optical trapping our lab has devised an alternative technique which utilizes near-field optics to move particles across a chip. Instead of focusing laser beams in the far-field, the optical near field of plasmonic resonators produces the necessary local optical intensity enhancement to overcome the restrictions of diffraction and manipulate particles at higher resolution. Closely-spaced resonators produce strong optical traps which can be addressed to mediate the hand-off of particles from one to the next in a conveyor-belt-like fashion. Here, we describe how to design and produce a conveyor belt using a gold surface patterned with plasmonic C-shaped resonators and how to operate it with polarized laser light to achieve super-resolution nanoparticle manipulation and transport. The nano-optical conveyor belt chip can be produced using lithography techniques and easily packaged and distributed.

The scalability and resolution of conventional optical manipulation techniques are limited by diffraction. We circumvent the diffraction limit and describe a method of optically transporting nanoparticles across a chip using a gold surface patterned with a path of closely spaced C-shaped plasmonic resonators.

Fabbricazione e funzionamento di un nano-ottica Nastro trasportatore

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological ...

Compact Lens-less Digital Holographic Microscope for MEMS Inspection and Characterization

A micro-electro-mechanical-system (MEMS) is a widely used component in many industries, including energy, biotechnology, medical, communications, and automotive. However, effective inspection and characterization metrology systems are needed to ensure the functional reliability of MEMS. This study presents a system based on digital holography as a tool for MEMS metrology. Digital holography has gained increasing attention in the past 20 years. With the fast development and decreasing cost of sensor arrays, resolution of such systems has increased broadening potential applications. Thus, it has attracted attention from both research and industry sides as a potential reliable tool for industrial metrology. Indeed, by recording the interference pattern between an object beam (which contains sample height information) and a reference beam on a CCD camera, one can retrieve the quantitative phase information of an object. However, most of digital holographic systems are bulky and thus not easy to implement on industry production lines. The novelty of the system presented is that it is lens-less and thus very compact. In this study, it is shown that the Compact Digital Holographic Microscope (CDHM) can be used to evaluate several characteristics typically consider as criteria in MEMS inspections. The surface profiles of MEMS in both static and dynamic conditions are presented. Comparison with AFM is investigated to validate the accuracy of the CDHM.

We present a compact reflection digital holographic system (CDHM) for inspection and characterization of MEMS devices. A lens-less design using a diverging input wave providing natural geometrical magnification is demonstrated. Both static and dynamic studies are presented.

Lens-meno compatta digitale olografico microscopio per MEMS di ispezione e caratterizzazione

A micro-electro-mechanical-system (MEMS) is a widely used component in many industries, including energy, biotechnology, medical, communications, and ...

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices have used devices prepared by spin coating, a process that is not amenable to large-scale fabrication. This mismatch in device fabrication makes it difficult to translate quantitative results obtained in the laboratory to the commercial level, making optimization difficult. Using a mini-slot die coater, this mismatch can be resolved by translating the commercial process to the laboratory and characterizing the structure formation in the active layer of the device in real time and in situ as films are coated onto a substrate. The evolution of the morphology was characterized under different conditions, allowing us to propose a mechanism by which the structures form and grow. This mini-slot die coater offers a simple, convenient, material efficient route by which the morphology in the active layer can be optimized under industrially relevant conditions. The goal of this protocol is to show experimental details of how a solar cell device is fabricated using a mini-slot die coater and technical details of running in situ structure characterization using the mini-slot die coater.

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Here, we present a protocol to fabricate organic thin film solar cells using a mini-slot die coater and related in-line structure characterizations using synchrotron scattering techniques.

La stampa Fabbricazione di massa eterogiunzione celle solari e<em&gt; In Situ</em&gt; Morfologia Caratterizzazione

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices ...

Fabrication of 1-D Photonic Crystal Cavity on a Nanofiber Using Femtosecond Laser-induced Ablation

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using femtosecond laser-induced ablation. We show that thousands of periodic nano-craters are fabricated on an optical nanofiber by irradiating with just a single femtosecond laser pulse. For a typical sample, periodic nano-craters with a period of 350 nm and with diameter gradually varying from 50 - 250 nm over a length of 1 mm are fabricated on a nanofiber with diameter around 450 - 550 nm. A key aspect of such a nanofabrication is that the nanofiber itself acts as a cylindrical lens and focuses the femtosecond laser beam on its shadow surface. Moreover, the single-shot fabrication makes it immune to mechanical instabilities and other fabrication imperfections. Such periodic nano-craters on nanofiber, act as a 1-D PhC and enable strong and broadband reflection while maintaining the high transmission out of the stopband. We also present a method to control the profile of the nano-crater array to fabricate apodized and defect-induced PhC cavities on the nanofiber. The strong confinement of the field, both transverse and longitudinal, in the nanofiber-based PhC cavities and the efficient integration to the fiber networks, may open new possibilities for nanophotonic applications and quantum information science.

We present a protocol for fabricating 1-D photonic crystal cavities on subwavelength diameter silica fibers (optical nanofibers) using femtosecond laser-induced ablation.

Fabbricazione di 1-D Photonic cristallo cavità su una nanofibre Utilizzando ablazione laser a femtosecondi-indotta

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using ...

Fabrication of Superhydrophobic Metal Surfaces for Anti-Icing Applications

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in industry. The wettability of the produced surface was analyzed by bouncing drop experiments and the topography was analyzed by confocal microscopy. In addition, we show various methodologies to measure its durability and anti-icing properties. Superhydrophobic surfaces hold a special texture that must be preserved to keep their water-repellency. To fabricate durable surfaces, we followed two strategies to incorporate a resistant texture. The first strategy is a direct incorporation of roughness to the metal substrate by acid etching. After this surface texturization, the surface energy was decreased by silanization or fluoropolymer deposition. The second strategy is the growth of a ceria layer (after surface texturization) that should enhance the surface hardness and corrosion resistance. The surface energy was decreased with a stearic acid film.
The durability of the superhydrophobic surfaces was examined by a particle impact test, mechanical wear by lateral abrasion, and UV-ozone resistance. The anti-icing properties were explored by studying the ability to repeal subcooled water, freezing delay, and ice adhesion.

We illustrate several methodologies to produce superhydrophobic metal surfaces and to explore their durability and anti-icing properties.

Fabbricazione di superfici superidrofobiche metalliche per applicazioni Anti-Icing

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in ...

Fused Filament Fabrication (FFF) of Metal-Ceramic Components

Technical ceramics are widely used for industrial and research applications, as well as for consumer goods. Today, the demand for complex geometries with diverse customization options and favorable production methods is increasing continuously. With fused filament fabrication (FFF), it is possible to produce large and complex components quickly with high material efficiency. In FFF, a continuous thermoplastic filament is melted in a heated nozzle and deposited below. The computer-controlled print head is moved in order to build up the desired shape layer by layer. Investigations regarding printing of metals or ceramics are increasing more and more in research and industry. This study focuses on additive manufacturing (AM) with a multi-material approach to combine a metal (stainless steel) with a technical ceramic (zirconia: ZrO2). Combining these materials offers a broad variety of applications due to their different electrical and mechanical properties. The paper shows the main issues in preparation of the material and feedstock, device development, and printing of these composites.

Fused Filament Fabrication FFF of Metal-Ceramic Components

This study shows multi-material additive manufacturing (AM) using fused filament fabrication (FFF) of stainless steel and zirconia.

Filamento fuso fabbricazione (FFF) dei componenti in metallo-ceramica

Technical ceramics are widely used for industrial and research applications, as well as for consumer goods. Today, the demand for complex geometries with ...