Name: fabrication of polymer microspheres for optical resonator and laser applications
Uploaded: 2017-06-02T15:00:00
Description: Watch this Scientific Journal Video about Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications at JoVE.com

This work was partly supported by KAKENHI (25708020, 15K13812, 15H00860, 15H00986, 16H02081) from JSPS/MEXT Japan, the Asahi Glass Foundation, and the University of Tsukuba Pre-strategic initiative, "Ensemble of light with matters and life."

1. Fabrication Protocols of Polymer Microspheres
<ol>
	<li>Vapor Diffusion Method
	<ol>
		<li>Dissolve 2 mg of conjugated polymers, such as P1 (poly[(9,9-dioctylfluorene-2,7-diyl)-alt-(5-octylthieno[3,4-c]pyrrole-4,6-dione-1,3-diyl)])28 and P2 (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)])28, in 2 mL of chloroform (a good solvent) in...

<ol>
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Actuators B. 136, 275-286 (2009).</li><li>Wu, C., Szymanski, C., Cain, Z., McNeill, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conjugated+Polymer+Dots+for+Multiphoton+Fluorescence+Imaging.">Conjugated Polymer Dots for Multiphoton Fluorescence Imaging.</a> J. Am. Chem. Soc. 129, 12904-12905 (2007).</li><li>Feng, L., Zhu, C., Yuan, H., Liu, L., Lv, F., Wang, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conjugated+Polymer+Nanoparticles:+Preparation,+Properties,+Functionalization+And+Biological+Applications.">Conjugated Polymer Nanoparticles: Preparation, Properties, Functionalization And Biological Applications.</a> Chem. Soc. Rev. 42, 6620-6634 (2013).</li><li>Pecher, J., Mecking, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoparticles+of+Conjugated+Polymers.">Nanoparticles of Conjugated Polymers.</a> Chem. Rev. 110, 6260-6279 (2010).</li><li>McGehee, M. D., Heeger, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Semiconducting+(Conjugated)+Polymers+as+Materials+for+Solid-State+Lasers.">Semiconducting (Conjugated) Polymers as Materials for Solid-State Lasers.</a> Adv. Mater. 12, 1655-1668 (2000).</li><li>Samuel, I. D. W., Turnbull, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organic+Semiconductor+Lasers.">Organic Semiconductor Lasers.</a> Chem. Rev. 107, 1272-1295 (2007).</li><li>Kuehne, A. J. C., Gather, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organic+Lasers:+Recent+Developments+on+Materials,+Device+Geometries,+and+Fabrication+Techniques.">Organic Lasers: Recent Developments on Materials, Device Geometries, and Fabrication Techniques.</a> Chem. Rev. 116, 12823-12864 (2016).</li><li>Furumi, S., Kanai, T., Sawada, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Widely+Tunable+Lasing+in+a+Colloidal+Crystal+Gel+Film+Permanently+Stabilized+by+an+Ionic+Liquid.">Widely Tunable Lasing in a Colloidal Crystal Gel Film Permanently Stabilized by an Ionic Liquid.</a> Adv. Mater. 23, 3815-3820 (2011).</li><li>Mikosch, A., Ciftci, S., Kuehne, A. J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Colloidal+Crystal+Lasers+from+Monodisperse+Conjugated+Polymer+Particles+via+Bottom-Up+Coassembly+in+a+Sol-Gel+Matrix.">Colloidal Crystal Lasers from Monodisperse Conjugated Polymer Particles via Bottom-Up Coassembly in a Sol-Gel Matrix.</a> ACS Nano. 10, 10195-10201 (2016).</li><li>Oraevsky, A. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whispering-Gallery+Waves.">Whispering-Gallery Waves.</a> Quant Electron. 32 (5), 377-400 (2002).</li><li>Yamamoto, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spherical+Resonators+from+&#960;-Conjugated+Polymers.">Spherical Resonators from &#960;-Conjugated Polymers.</a> Polym. J. 48, 1045-1050 (2016).</li><li>Adachi, T., 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=Spherical+Assemblies+from+&#960;+-Conjugated+Alternating+Copolymers:+Toward+Optoelectronic+Colloidal+Crystals.">Spherical Assemblies from &#960; -Conjugated Alternating Copolymers: Toward Optoelectronic Colloidal Crystals.</a> J. Am. Chem. Soc. 135, 870-876 (2013).</li><li>Tong, L., 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=Tetramethylbithiophene+in+&#960;-Conjugated+Alternating+Copolymers+as+an+Effective+Structural+Component+for+the+Formation+of+Spherical+Assemblies.">Tetramethylbithiophene in &#960;-Conjugated Alternating Copolymers as an Effective Structural Component for the Formation of Spherical Assemblies.</a> Polym. 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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 mic...

Polymer nano/micro-sized particles are widely used for a variety of applications, including as catalyst support, column chromatography fillers, drug delivery agents, fluorescent probes for cell tracking, optical media, and so forth1,2,3,4,5,6,7,8,9. In particular, &#960;-conjugated polymers have inherent luminescent and charge conducting properties that are beneficial to optical, electronic, and optoelectronic applications using polymer spheres10,11,12,13,14, especially laser applications using soft organic materials15,16,17. For example, the three-dimensional integration of spheres with several hundred nanometer diameters forms colloidal crystals, which show photonic band gaps at a certain wavelength18,19. When light is confined in the intersphere periodic structure, lasing action appears at the middle of the stop band. On the other hand, when the size of the spheres increases to the several-micrometer scale, light is confined inside a single microsphere via total internal reflection at the polymer/air interface20. Propagation of the light wave at the maximum circumference results in interference, leading to the appearance of a resonant mode with sharp and periodic emission lines. These optical modes are so-called &#34;whispering gallery modes&#34; (WGMs). The term &#34;whispering gallery&#34; originated from St. Paul&#39;s Cathedral in London, where sound waves propagate along the circumference of the wall, allowing whispers to be heard by a person on the other side of the gallery. Because the wavelength of light is on the sub-micrometer scale, which is far smaller than sound waves, such a large dome is not necessary for the WGM of light: tiny, micrometer-scale, well-defined vessels, such as microspheres, microdiscs, and microcrystals, fulfill the WGM conditions.
Equation 1 is a simple form of the WGM resonating condition21:
n&#960;d = l&#955;&#160;&#160;&#160;&#160;&#160; (1)
where n is the refractive index of the resonator, d is the diameter, l is the integer number, and &#955; is the wavelength of the light. The left part of (1) is the optical path length through one circle propagation. When the optical path coincides with the integer multiple of the wavelength, resonance occurs, while at the other wavelength, the light wave is diminished upon rounding.
This paper introduces several experimental methods to prepare microspheres for WGM resonators from conjugated polymers in solution: vapor diffusion22,23,24,25,26,27,28,29,30, mini-emulsion31, and interface precipitation32. Each method has unique characteristics; for example, the vapor diffusion method affords well-defined microspheres with very high sphericity and smooth surfaces, but only low-crystallinity polymers can form these microspheres. On the other hand, for the mini-emulsion method, various kinds of conjugated polymers, including high-crystalline polymers, can form spheres, but the surface morphology is inferior to that obtained from the vapor diffusion method. The interface precipitation method is preferable for creating microspheres from dye-doped, non-conjugated polymers. In all cases, the selection of the solvent and the non-solvent plays an important role in the formation of spherical morphology.
In the second half of this paper, &#181;-PL and micro-manipulation techniques are presented. For the &#181;-PL technique, microspheres are dispersed on a substrate, and a focused laser beam, through a microscope lens, is used to irradiate a single isolated microsphere24. The generated PL from a sphere is detected by a spectrometer through the microscope lens. Moving the sample stage can vary the position of the excitation spot. The detection point is also variable by tilting the collimator optics of the excitation laser beam with respect to the optical axis of the detection path28,32. To investigate intersphere light propagation and wavelength conversion, the micro-manipulation technique can be used32. To connect several microspheres with different optical properties, it is possible to pick up one sphere using a micro-needle and put it on another sphere. In conjunction with the micromanipulation techniques and the &#181;-PL method, various optical measurements can be carried out using conjugated polymer spheres, which are prepared by a simple self-assembly method. This video paper will be useful to readers who wish to use soft polymer materials for optical applications.

<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

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, &#960;-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (&#181;-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, &#181;-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Figure 1 shows schematic representations of the vapor diffusion method (a), mini-emulsion method (b), and interface precipitation method (c). For the vapor diffusion method (Figure 1a), a 5 mL vial containing a CHCl3 solution of polymers (0.5 mg mL-1, 2 mL) was placed in a 50 mL vial containing 5 mL of a non-solvent, such as MeOH. The outside vial was capped and then allowed to stand for 3 days at 25 &#176;C...

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

Protocols for the synthesis of microspheres from polymers, the manipulation of microspheres, and micro-photoluminescence measurements are presented.

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

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Engineering

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, ...

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 ...

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 ...

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 ...

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 ...

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

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 ...

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 ...

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 ...

Fused Filament Fabrication (FFF) of Metal-Ceramic Components

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 ...

Design and Fabrication of an Optical Fiber Made of Water

In this report, an optical fiber of which the core is made solely of water, while the cladding is air, is designed and manufactured. In contrast with ...