We have no acknowledgements.

Caution: Please wear a lab-coat, gloves, and safety glasses and read material safety data sheets (MSDS) before use. All purchased materials have been used without further purification.
1. Preparation of Emulsions Consisting of Styrene/PFO/Aqueous SDS Solution Mixtures
<ol>
	<li>To prepare 5 mM of aqueous SDS solution, dissolve 14.5 mg of SDS in 10 mL of high-purity H2O. 
	NOTE: High-purity H2O has been used (resistivity (R) = 18 M&#937; cm, surface tension (&#947;) = 72.0 mN m-1 at 25 &#176;C).</li>
	<li>Add 1.5 g of styrene, 0.6 g of PFO, and 0.9 g of 5 mM of aqueous SDS solution to a 10 mL glass vial with a stir bar. 
	NOTE: In scanning confocal fluorescence microscopy observations, add 2.6 mg of coumarin 102 and 0.062 mg of calcein to the mixture.</li>
	<li>Stir the mixture for 60 min at 1,150 rpm under room temperature and then raise the temperature to 80 &#176;C.</li>
	<li>Stir the mixture for 60 min at 1,150 rpm and 80 &#176;C.</li>
</ol>
2. Fabrication of polymer particles using Emulsions Consisting of Styrene/PFO/Aqueous SDS Solution Mixtures
<ol>
	<li>Add 3.9 mg of potassium peroxodisulfate, 2 mg of pyrene, 1.5 g of styrene, 0.6 g of PFO, and 0.9 g of 5 mM of aqueous SDS solution to a 10 mL glass vial with a stir bar and seal it with a rubber septum.</li>
	<li>Deoxygenate the mixture by bubbling nitrogen gas through a syringe needle for 30 min. 
	Caution: Slowly flow the nitrogen gas to not generate a large amount of foam.</li>
	<li>To prepare the emulsion, stir the mixture for 60 min at 1,150 rpm and room temperature and then raise the temperature to 80 &#176;C.</li>
	<li>Stir the mixture for 30 min at 1,150 rpm and 80 &#176;C.</li>
	<li>Transfer the cloudy part (1.8 mL) in the resultant solution (3 mL) to the test tube and then add 30% aqueous ethanol solution to completely terminate the polymerization reaction.</li>
	<li>Sonicate (Power: 130 W, Frequency: 4.2 kHz) for 10 min to wash resultant polymer particles and then centrifuge for 10 min at 2300 x g.</li>
	<li>To obtain the polymer particles, remove the supernatant solution from the test tube.</li>
	<li>Add 3 mL of water to the resultant solids in the test tube. Sonicate (Power: 130 W, Frequency: 4.2 kHz) for 10 min and centrifuge for 10 min at 2300 x g. Remove the supernatant solution from the test tube.</li>
	<li>Repeat the washing procedure (Step 2.8) until foam is not generated from the supernatant solution. Evaporate water to obtain the solid of hollow polymer particles.</li>
</ol>
3. Preparation of microcapsules using the hollow polymer particles
<ol>
	<li>Add 1 mg of hollow polystyrene particles (step 2.9) and 4 mL of water to a 10 mL glass vial with a stir bar.</li>
	<li>Sonicate (Power: 130 W, Frequency: 4.2 kHz) for 10 min to disperse the hollow particles in water.</li>
	<li>Add 0.1 mL of toluene to the water dispersed the particles and then stir it for 1 h at 100 rpm under room temperature. Transfer the liquid to a test tube. 
	Caution: If the rotation per minute increases, the morphology of particles will deform.</li>
	<li>Centrifuge the liquid for 10 min at 2300 x g to isolate the microcapsules form it. Remove the supernatant solution from the test tube.</li>
</ol>

<ol>
	<li>Okubo, M., Fujibayashi, T., Terada, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+micron-sized,+monodisperse+polymer+particles+of+disc-like+and+polyhedral+shapes+by+seeded+dispersion+polymerization.">Synthesis of micron-sized, monodisperse polymer particles of disc-like and polyhedral shapes by seeded dispersion polymerization.</a> Colloid Polym Sci. 283 (7), 793-798 (2005).</li><li>Fujibayashi, T., Okubo, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+Thermodynamic+Stability+of+Micron-Sized,+Monodisperse+Composite+Polymer+Particles+of+Disc-like+Shapes+by+Seeded+Dispersion+Polymerization.">Preparation and Thermodynamic Stability of Micron-Sized, Monodisperse Composite Polymer Particles of Disc-like Shapes by Seeded Dispersion Polymerization.</a> Langmuir. 23 (15), 7958-7962 (2007).</li><li>Okubo, M., Fujibayashi, T., Yamada, M., Minami, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micron-sized,+monodisperse,+snowman/confetti-shaped+polymer+particles+by+seeded+dispersion+polymerization.">Micron-sized, monodisperse, snowman/confetti-shaped polymer particles by seeded dispersion polymerization.</a> Colloid Polym Sci. 283 (9), 1041-1045 (2005).</li><li>Xu, S., 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=Generation+of+Monodisperse+Particles+by+Using+Microfluidics:+Control+over+Size,+Shape,+and+Composition.">Generation of Monodisperse Particles by Using Microfluidics: Control over Size, Shape, and Composition.</a> Angew Chem Int Ed. 44 (5), 724-728 (2005).</li><li>Serra, C. A., Chang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic-Assisted+Synthesis+of+Polymer+Particles.">Microfluidic-Assisted Synthesis of Polymer Particles.</a> Chem Eng Tech. 31 (8), 1099-1115 (2008).</li><li>Higuchi, T., Yabu, H., Shimomura, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simple+preparation+of+hemispherical+polystyrene+particles.">Simple preparation of hemispherical polystyrene particles.</a> Colloids Surf A. 284, 250-253 (2006).</li><li>Sun, Z. Q., 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=Nonspherical+Colloidal+Crystals+Fabricated+by+the+Thermal+Pressing+of+Colloidal+Crystal+Chips.">Nonspherical Colloidal Crystals Fabricated by the Thermal Pressing of Colloidal Crystal Chips.</a> Langmuir. 21 (20), 8987-8991 (2005).</li><li>Deng, Y., 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=A+novel+approach+to+the+construction+of+3-D+ordered+macrostructures+with+polyhedral+particles.">A novel approach to the construction of 3-D ordered macrostructures with polyhedral particles.</a> J Mater Chem. 18 (4), 408-415 (2008).</li><li>Hyuk Im, S., Jeong, U., Xia, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymer+hollow+particles+with+controllable+holes+in+their+surfaces.">Polymer hollow particles with controllable holes in their surfaces.</a> Nat Mater. 4 (9), 671-675 (2005).</li><li>Saito, N., Kagari, Y., Okubo, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Colloidal+Stabilizer+on+the+Shape+of+Polystyrene/Poly(methyl+methacrylate)+Composite+Particles+Prepared+in+Aqueous+Medium+by+the+Solvent+Evaporation+Method.">Effect of Colloidal Stabilizer on the Shape of Polystyrene/Poly(methyl methacrylate) Composite Particles Prepared in Aqueous Medium by the Solvent Evaporation Method.</a> Langmuir. 22 (22), 9397-9402 (2006).</li><li>Cai, P. -. j., Tang, Y. -. j., Wang, Y. -. t., Cao, Y. -. j. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+polystyrene+hollow+spheres+in+W/O/W+multiple+emulsions.">Fabrication of polystyrene hollow spheres in W/O/W multiple emulsions.</a> Mater Chem Phys. 124 (1), 10-12 (2010).</li><li>Liang, S. -. S., Chen, S. -. L., Chen, S. -. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diverse+macroporous+spheres+synthesized+by+multiple+emulsion+polymerization+for+protein+analyses.">Diverse macroporous spheres synthesized by multiple emulsion polymerization for protein analyses.</a> Chem Commun. 47 (29), 8385-8387 (2011).</li><li>Kondo, Y., Yoshino, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hybrid+fluorocarbon/hydrocarbon+surfactants.">Hybrid fluorocarbon/hydrocarbon surfactants.</a> Curr Opin Colloid Interface Sci. 10 (3-4), 88-93 (2005).</li><li>Takahashi, Y., Kondo, Y., Schmidt, J., Talmon, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Self-Assembly+of+a+Fluorocarbon-Hydrocarbon+Hybrid+Surfactant:+Dependence+of+Morphology+on+Surfactant+Concentration+and+Time.">Self-Assembly of a Fluorocarbon-Hydrocarbon Hybrid Surfactant: Dependence of Morphology on Surfactant Concentration and Time.</a> J Phys Chem B. 114 (42), 13319-13325 (2010).</li><li>Takahashi, Y., Nasu, Y., Aramaki, K., Kondo, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unusual+viscoelastic+behavior+of+aqueous+solutions+of+fluorocarbon-hydrocarbon+hybrid+surfactant+and+its+morphological+transformations.">Unusual viscoelastic behavior of aqueous solutions of fluorocarbon-hydrocarbon hybrid surfactant and its morphological transformations.</a> J Fluor Chem. 145, 141-147 (2013).</li><li>Yoshino, N., 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=Syntheses+of+Hybrid+Anionic+Surfactants+Containing+Fluorocarbon+and+Hydrocarbon+Chains.">Syntheses of Hybrid Anionic Surfactants Containing Fluorocarbon and Hydrocarbon Chains.</a> Langmuir. 11 (2), 466-469 (1995).</li><li>Zarzar, L. D., 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=Dynamically+reconfigurable+complex+emulsions+via+tunable+interfacial+tensions.">Dynamically reconfigurable complex emulsions via tunable interfacial tensions.</a> Nature. 518 (7540), 520-524 (2015).</li></ol>

We have nothing to disclose.

The emulsions containing Janus droplets of styrene and PFO were obtained above 10 wt% of the weight fraction of aqueous SDS concentration and any weight fraction of styrene and PFO. When the various weight-fractions of the emulsions containing the Janus droplets have been polymerized for 30 min, the hollow polystyrene particles can be obtained for all composition. These results indicate that the protocol demonstrated here is simple. In addition, the diameter, hole size, and hole volume of the hollow polystyrene particles can be controlled by the polymerization time in the method described here.
We suggest the following mechanism for the fabrication of the hollow polystyrene particles. Janus oil droplets consisting of styrene and PFO formed in the O/W emulsions containing mixtures of aqueous SDS solution, styrene, and PFO at 80 &#176;C. PFO droplets are located on the surface of styrene droplets. Since KPS, an initiator of the polymerization, is soluble in the water phase, the polymerization will progress at the interface of the styrene/aqueous SDS solution. Styrene in the ternary emulsions was polymerized to polystyrene at 80 &#176;C, whereas PFO, having no polymerizable groups, remained in the emulsions at that temperature. After the polymerization was terminated, a hole on the polystyrene particle was formed by removal of PFO. Therefore, the hollow cup-type polystyrene particles having a hole on the surface were fabricated atany weight fraction of styrene and PFO and all polymerization times.
Adding a small amount of toluene to the hollow polystyrene particles fabricated by radical polymerization for 90 min brings about sealing the holes on the hollow polystyrene particles. This phenomena is consistent with that reported by Hyuk et al.9. The capsulation method can contain an aqueous material in the particles.
In this article, we have demonstrated a fabrication method of hollow polymer particles using Janus oil droplets consisting of styrene and PFO, which are mutually immiscible. The preparation method of non-spherical polymer particles has already been studied because of their potential use in various applications. This strategy using Janus oil droplets of hydrocarbon oil and fluorocarbon oil will apply to the fabrication of non-spherical polymer particles from various types of monomer and drug delivery system.

While spherical polymer particles have been widely used in various industrial applications, it is well-known that dimple particles, hemispheres, disks, and ellipsoids, have been prepared by seeded polymerizations1,2,3, photo-polymerization of non-spherical monomer droplets using microreactor with specific geometries4,5, self-organization using reprecipitation of polymers6, and deformation of spherical polymer particles by mechanical external forces7,8. In particular, hollow polymer particles with micrometer-size have been fabricated by evaporation of a good solvent from spherical polymer particles swollen by the solvent9,10 and polymerization using multiple emulsions11,12.
In this work, we focus on the usage of mutual immiscibility of hydrocarbon and fluorocarbon oils in the fabrication of polymer particles. Hybrid surfactants have a hydrocarbon chain and a fluorocarbon chain in the molecule. Previously, we have reported the unique properties of hybrid surfactants that are not observed in conventional surfactants13,14,15. We have also studied emulsions using hydrocarbon oil, fluorocarbon oil, and aqueous surfactant solution, which are mutually immiscible16. However, there are very few studies of the emulsions17. These studies have described the morphology of oil droplets consisting of hydrocarbon oil and fluorocarbon oil in aqueous surfactant solutions.
Here, we show a detailed protocol of the fabrication of hollow polymer particles by radical polymerization using oil droplets in emulsions consisting of hydrocarbon oil, fluorocarbon oil, and aqueous sodium dodecylsulfate (SDS) solutions. We suggest a new strategy, which is different from conventional methods, for the preparation of non-spherical polymer particles. This method can simply fabricate the hollow polymer particles in a short time. In addition, the protocol of the preparation of microcapsules through the hollow polymer particles is shown.

<table>
	<tbody>
		<tr>
			<td>Material</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium dodecylsulfate, 95.0%</td>
			<td>Wako Pure Chemical Industries, Ltd.</td>
			<td>192-08672</td>
			<td></td>
		</tr>
		<tr>
			<td>Styrene, 99.0%</td>
			<td>Tokyo Chemical Industry Co. Ltd.</td>
			<td>S0095</td>
			<td></td>
		</tr>
		<tr>
			<td>Perfluorooctane, 99%</td>
			<td>Fluorochem Ltd.</td>
			<td>8706</td>
			<td></td>
		</tr>
		<tr>
			<td>Coumarin 102, 97.0%</td>
			<td>Tokyo Chemical Industry Co. Ltd.</td>
			<td>C2267</td>
			<td></td>
		</tr>
		<tr>
			<td>Calcein</td>
			<td>Dojindo Molecular Technologies, Inc.</td>
			<td>C001</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium peroxodisulfate, 98.0%</td>
			<td>Kanto Chemical Co., Inc.</td>
			<td>32375-30</td>
			<td></td>
		</tr>
		<tr>
			<td>Pyrene, 97.0%</td>
			<td>Wako Pure Chemical Industries, Ltd.</td>
			<td>167-05302</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol, 99.5%</td>
			<td>Kanto Chemical Co., Inc.</td>
			<td>14033-00</td>
			<td></td>
		</tr>
		<tr>
			<td>Toluene, 99.5%</td>
			<td>Kanto Chemical Co., Inc.</td>
			<td>40180-00</td>
			<td></td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Scanning Electron Microscope</td>
			<td>Hitachi High-Technologies Corporation</td>
			<td>S-4800</td>
			<td></td>
		</tr>
		<tr>
			<td>Scanning Transmission Electron Microscope</td>
			<td>Hitachi High-Technologies Corporation</td>
			<td>S-4800</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasonic cleaner</td>
			<td>Branson Ultrasonics, Emerson Japan, Ltd.</td>
			<td>Model 3510</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>AS ONE Corporation</td>
			<td>CN-1050</td>
			<td></td>
		</tr>
	</tbody>
</table>

preparation of hollow polystyrene particles and microcapsules by radical polymerization of janus droplets consisting of hydrocarbon and fluorocarbon oils

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) and fluorocarbon oil (perfluoro-n-octane, PFO) in aqueous surfactant (sodium dodecylsulfate, SDS) solutions. Since fluorocarbon oils are immiscible with hydrocarbon oils, the two oils are separated. Emulsions are prepared by stirring styrene/PFO/aqueous SDS solution mixtures at 80 &#176;C. The type of emulsions and the morphology of droplets in the emulsions are observed by light microscope and scanning confocal fluorescence microscope. It is found that oil droplets with Janus-type morphologies consisting of mutually immiscible styrene and PFO are formed in aqueous SDS solutions. Polystyrene particles are fabricated by radical polymerization of the ternary mixtures of styrene/PFO/aqueous SDS solution at 80 &#176;C. The morphologies of the polystyrene are confirmed by scanning electron microscopy and scanning transmission electron microscopy observations. These observations show the preparation of hollow polystyrene particles with a single hole on the surface. To our knowledge, this method is a novel strategy using the immiscibility of hydrocarbon and fluorocarbon oils. The hollow particles can also be applied to the preparation of microcapsules.

Light and scanning confocal fluorescence microscopy observations were performed to determine the morphology and composition of droplets in the emulsions consisting of styrene, PFO, and 5 mM aqueous SDS solution (Figure 1). Scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) observations showed the formation of hollow particles and microcapsules (Figure 2).
The DIC and confocal fluorescence microscopy images of emulsions consisting of ternary mixtures of styrene/PFO/aqueous SDS solution indicate that the continuous phase is aqueous SDS solution, because green fluorescence corresponding to calcein was observed in the continuous phase, and therefore, oil-in-water type emulsions are formed (Figure 1a and 1b). These images also show that the oil droplets consist of styrene and PFO, which are mutually immiscible. The DIC and confocal fluorescence microscopy images of emulsions containing coumarin 102 reveal that a PFO droplet is located at the interface between water and a styrene droplet. The ternary mixtures of styrene, PFO, and aqueous SDS solution at 5 mM form emulsions containing Janus oil droplets, which consist of styrene and PFO.
The SEM and STEM images of polymer particles fabricated by the radical polymerization of the emulsions of styrene/PFO/5 mM aqueous SDS solution show the preparation of hollow non-spherical polystyrene particles with a hole on the surface (Figure 2a and 2b). The formation rate, diameter, and hole size of the hollow polystyrene particles are evaluated by observing 200 particles through SEM and STEM. The averaged diameter estimated from SEM observations is 1.3 &#181;m. The size is consistent with the diameter of the polymer particles estimated from dynamic light scattering measurements. The formation rate is approximately 100%. The averaged hole-size and volume of the hole in the hollow particles are 0.8 &#177; 0.4 &#181;m and 0.9 &#177; 0.4 &#181;m3, respectively. Therefore, the hollow polystyrene particles having a 0.8 &#181;m hole were fabricated by radical polymerization of Janus droplets containing styrene in the emulsions.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56922/56922fig1.jpg" /> 
Figure 1. Morphologies of droplets in emulsions consisting of styrene, PFO, and 5 mM aqueous SDS solution. (a) Differential interference contrast (DIC) and (b) confocal fluorescence microscopy images of the emulsions containing aqueous fluorescent calcein. (c) DIC and (d) confocal fluorescence microscopy images of the emulsions containing oil-soluble fluorescent coumarin 102. <a href="https://cloudflare.jove.com/files/ftp_upload/56922/56922fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56922/56922fig2.jpg" /> 
Figure 2. Morphologies of hollow polystyrene particles and microcapsules fabricated using emulsions consisting of styrene, PFO, and 5 mM aqueous SDS solution. (a) SEM and (b) STEM images of the hollow polystyrene particles. (c) SEM and (d) STEM images of the microcapsules. <a href="https://cloudflare.jove.com/files/ftp_upload/56922/56922fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils at J

Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils

A protocol for the fabrication of hollow polymer particles and microcapsules by radical polymerization using emulsions consisting of styrene, perfluoro-n-octane, and aqueous SDS (sodium dodecylsulfate) solution is presented.

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) ...

preparation-hollow-polystyrene-particles-microcapsules-radical

Research

JoVE Journal

Chemistry

9.9K Views.  Tokyo University of Science. A protocol for the fabrication of hollow polymer particles and microcapsules by radical polymerization using emulsions consisting of styrene, perfluoro-n-octane, and aqueous SDS (sodium dodecylsulfate) solution is presented.

Video: Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils

Origami Inspired Self-assembly of Patterned and Reconfigurable Particles

There are numerous techniques such as photolithography, electron-beam lithography and soft-lithography that can be used to precisely pattern two dimensional (2D) structures. These technologies are mature, offer high precision and many of them can be implemented in a high-throughput manner. We leverage the advantages of planar lithography and combine them with self-folding methods1-20 wherein physical forces derived from surface tension or residual stress, are used to curve or fold planar structures into three dimensional (3D) structures. In doing so, we make it possible to mass produce precisely patterned static and reconfigurable particles that are challenging to synthesize.
In this paper, we detail visualized experimental protocols to create patterned particles, notably, (a) permanently bonded, hollow, polyhedra that self-assemble and self-seal due to the minimization of surface energy of liquefied hinges21-23 and (b) grippers that self-fold due to residual stress powered hinges24,25. The specific protocol described can be used to create particles with overall sizes ranging from the micrometer to the centimeter length scales. Further, arbitrary patterns can be defined on the surfaces of the particles of importance in colloidal science, electronics, optics and medicine. More generally, the concept of self-assembling mechanically rigid particles with self-sealing hinges is applicable, with some process modifications, to the creation of particles at even smaller, 100 nm length scales22, 26 and with a range of materials including metals21, semiconductors9 and polymers27. With respect to residual stress powered actuation of reconfigurable grasping devices, our specific protocol utilizes chromium hinges of relevance to devices with sizes ranging from 100 &mu;m to 2.5 mm. However, more generally, the concept of such tether-free residual stress powered actuation can be used with alternate high-stress materials such as heteroepitaxially deposited semiconductor films5,7 to possibly create even smaller nanoscale grasping devices.

We describe experimental details of the synthesis of patterned and reconfigurable particles from two dimensional (2D) precursors. This methodology can be used to create particles in a variety of shapes including polyhedra and grasping devices at length scales ranging from the micro to centimeter scale.

There are numerous techniques such as photolithography, electron-beam lithography and soft-lithography that can be used to precisely pattern two ...

Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow

While the first Electron Paramagnetic Resonance (EPR) studies regarding the effects of oxidation on the structure and stability of carbon radicals date back to the early 1980s the focus of these early papers primarily characterized the changes to the structures under extremely harsh conditions (pH or temperature)1-3. It is also known that paramagnetic molecular oxygen undergoes a Heisenberg spin exchange interaction with stable radicals that extremely broadens the EPR signal4-6. Recently, we reported interesting results where this interaction of molecular oxygen with a certain part of the existing stable radical structure can be reversibly affected simply by flowing a diamagnetic gas through the carbon samples at STP7. As flows of He, CO2, and N2 had a similar effect these interactions occur at the surface area of the macropore system.
This manuscript highlights the experimental techniques, work-up, and analysis towards affecting the existing stable radical nature in the carbon structures. It is hoped that it will help towards further development and understanding of these interactions in the community at large.

Stable radicals that are present in carbon substrates interact with paramagnetic oxygen through a Heisenberg spin exchange. This interaction can be significantly reduced under STP conditions by flowing a diamagnetic gas over the carbon system. This manuscript describes a simple method to characterize the nature of those radicals.

While the first Electron Paramagnetic Resonance (EPR) studies regarding the effects of oxidation on the structure and stability of carbon radicals date ...

Facile and Efficient Preparation of Tri-component Fluorescent Glycopolymers via RAFT-controlled Polymerization

Synthetic glycopolymers are instrumental and versatile tools used in various biochemical and biomedical research fields. An example of a facile and efficient synthesis of well-controlled fluorescent statistical glycopolymers using reversible addition-fragmentation chain-transfer (RAFT)-based polymerization is demonstrated. The synthesis starts with the preparation of &#946;-galactose-containing glycomonomer 2-lactobionamidoethyl methacrylamide obtained by reaction of lactobionolactone and N-(2-aminoethyl) methacrylamide (AEMA). 2-Gluconamidoethyl methacrylamide (GAEMA) is used as a structural analog lacking a terminal &#946;-galactoside. The following RAFT-mediated copolymerization reaction involves three different monomers: N-(2-hydroxyethyl) acrylamide as spacer, AEMA as target for further fluorescence labeling, and the glycomonomers. Tolerant of aqueous systems, the RAFT agent used in the reaction is (4-cyanopentanoic acid)-4-dithiobenzoate. Low dispersities (&#8804;1.32), predictable copolymer compositions, and high reproducibility of the polymerizations were observed among the products. Fluorescent polymers are obtained by modifying the glycopolymers with carboxyfluorescein succinimidyl ester targeting the primary amine functional groups on AEMA. Lectin-binding specificities of the resulting glycopolymers are verified by testing with corresponding agarose beads coated with specific glycoepitope recognizing lectins. Because of the ease of the synthesis, the tight control of the product compositions and the good reproducibility of the reaction, this protocol can be translated towards preparation of other RAFT-based glycopolymers with specific structures and compositions, as desired.

An efficient, three-step synthesis of RAFT-based fluorescent glycopolymers, consisting of glycomonomer preparation, copolymerization, and post-modification, is demonstrated. This protocol can be used to prepare RAFT-based statistical glycopolymers with desired structures.

Synthetic glycopolymers are instrumental and versatile tools used in various biochemical and biomedical research fields. An example of a facile and ...

Using Polystyrene-block-poly(acrylic acid)-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization

We present a template-free method for &#8220;polymerizing&#8221; nanoparticles into long chains without side branches. A variety of nanoparticles are encapsulated in polystyrene-block-poly(acrylic acid) (PSPAA) shells and then used as monomers for their self-assembly. Spherical PSPAA micelles upon acid treatment are known to assemble into cylindrical micelles. Exploiting this tendency, the core-shell nanoparticles are induced to aggregate, coalesce, and then transform into long chains. When more than one type of nanoparticles are used, random and block &#8220;copolymers&#8221; of nanoparticles can be obtained. Detailed procedures are reported for the PSPAA encapsulation of nanoparticles, homo- and co-polymerization of the core-shell nanoparticles, separation and purification of the resulting nanoparticle chains. Transformations of single-line chains into double- and triple-line chains are also presented. The synergy between the polymer shell and the embedded nanoparticles leads to an unusual chain-growth polymerization mode, giving long nanoparticle chains that are distinct from the products of the traditional step-growth aggregation process.

Using Polystyrene-block-polyacrylic acid-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization

We report protocols for &#8220;polymerizing&#8221; various types of polymer-encapsulated metal nanoparticles into long chains of &#8220;homo-&#8220; and &#8220;co-polymers&#8221;.

We present a template-free method for &#8220;polymerizing&#8221; nanoparticles into long chains without side branches. A variety of nanoparticles are ...

Facile Preparation of Internally Self-assembled Lipid Particles Stabilized by Carbon Nanotubes

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled (functionalized) CNTs are used as stabilizers to produce Pickering type oil-in-water (O/W) emulsions. Lipids namely, Dimodan U and Phytantriol are used as emulsifiers, which in excess water self-assemble into the bicontinuous cubic Pn3m phase. This highly viscous phase is fragmented into smaller particles using a probe ultrasonicator in presence of conventional surfactant stabilizers or CNTs as done here. Initially, the CNTs (powder form) are dispersed in water followed by further ultrasonication with the molten lipid to form the final emulsion. During this process the CNTs get coated with lipid molecules, which in turn are presumed to surround the lipid droplets to form a particulate emulsion that is stable for months. The average size of CNT-stabilized nanostructured lipid particles is in the submicron range, which compares well with the particles stabilized using conventional surfactants. Small angle X-ray scattering data confirms the retention of the original Pn3m cubic phase in the CNT-stabilized lipid dispersions as compared to the pure lipid phase (bulk state). Blue shift and lowering of the intensities in characteristic G and G&#39; bands of CNTs observed in Raman spectroscopy characterize the interaction between CNT surface and lipid molecules. These results suggest that the interactions between the CNTs and lipids are responsible for their mutual stabilization in aqueous solutions. As the concentrations of CNTs employed for stabilization are very low and lipid molecules are able to functionalize the CNTs, the toxicity of CNTs is expected to be insignificant while their biocompatibility is greatly enhanced. Hence the present approach finds a great potential in various biomedical applications, for instance, for developing hybrid nanocarrier systems for the delivery of multiple functional molecules as in combination therapy or polytherapy.

We report on a smart application of carbon nanotubes for kinetic stabilization of lipid particles that contain self-assembled nanostructures in their cores. The preparation of lipid particles requires rather low concentrations of carbon nanotubes permitting their use in biomedical applications such as drug delivery.

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled ...

Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The procedure is performed under an inert atmosphere using air- and water-exclusion techniques. The outcome of the polymerization is affected by the ratios of monomer, initiator, and catalyst used as well as the reaction concentration, solvent, and nature of the light source. Temporal control over the polymerization can be exercised by turning the visible light source off and on. Low dispersities of the resultant polymers as well as the ability to chain-extend to form block copolymers suggest control over the polymerization, while chain end-group analysis provides evidence supporting an atom-transfer radical polymerization mechanism.

A method for the atom transfer radical polymerization of functionalized vinyl monomers using perylene as a visible-light photocatalyst is described.

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The ...

On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes

The shift to heavy crude oils and the use of alternative fossil resources such as shale oil are a challenge for the petrochemical industry. The composition of heavy crude oils and shale oils varies substantially depending on the origin of the mixture. In particular they contain an increased amount of nitrogen containing compounds compared to the conventionally used sweet crude oils. As nitrogen compounds have an influence on the operation of thermal processes occurring in coker units and steam crackers, and as some species are considered as environmentally hazardous, a detailed analysis of the reactions involving nitrogen containing compounds under pyrolysis conditions provides valuable information. Therefore a novel method has been developed and validated with a feedstock containing a high nitrogen content, i.e., a shale oil. First, the feed was characterized offline by comprehensive two-dimensional gas chromatography (GC &#215; GC) coupled with a nitrogen chemiluminescence detector (NCD). In a second step the on-line analysis method was developed and tested on a steam cracking pilot plant by feeding pyridine dissolved in heptane. The former being a representative compound for one of the most abundant classes of compounds present in shale oil. The composition of the reactor effluent was determined via an in-house developed automated sampling system followed by immediate injection of the sample on a GC &#215; GC coupled with a time-of-flight mass spectrometer (TOF-MS), flame ionization detector (FID) and NCD. A novel method for quantitative analysis of nitrogen containing compounds using NCD and 2-chloropyridine as an internal standard has been developed and demonstrated.

A method combining comprehensive two-dimensional gas chromatography with nitrogen chemiluminescence detection has been developed and applied to on-line analysis of nitrogen containing compounds in a complex hydrocarbon matrix.

The shift to heavy crude oils and the use of alternative fossil resources such as shale oil are a challenge for the petrochemical industry. The ...

Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by &#960;-&#960; Stacking Interactions

In this study, an amphiphilic copolymer that includes a core-forming block with phenyl groups was synthesized by living anionic polymerization of phenyl glycidyl ether (PheGE) on methoxy-polyethylene glycol (mPEG-b-PPheGE). Characterization of the copolymer revealed a narrow molecular distribution (PDI &#60; 1.03) and confirmed the degree of polymerization of mPEG122-b-(PheGE)15. The critical micelle concentration of the copolymer was evaluated using an established fluorescence method with the aggregation behavior evaluated by dynamic light scattering and transmission electronic microscopy. The potential of the copolymer for use in drug delivery applications was evaluated in a preliminary manner including in vitro biocompatibility, loading and release of the hydrophobic anti-cancer drug doxorubicin (DOX). A stable micelle formulation of DOX was prepared with drug loading levels up to 14% (wt%), drug loading efficiencies &#62; 60% (w/w) and sustained release of drug over 4 days under physiologically relevant conditions (acidic and neutral pH, presence of albumin). The high drug loading level and sustained release is attributed to stabilizing &#960;-&#960; interactions between DOX and the core-forming block of the micelles.

The key steps of living anionic polymerization of phenyl glycidyl ether (PheGE) on methoxy-polyethylene glycol (mPEG-b-PPheGE) are described. The resulting block copolymer micelles (BCMs) were loaded with doxorubicin 14% (wt%) and sustained release of drug over 4 days under physiologically relevant conditions was obtained.

In this study, an amphiphilic copolymer that includes a core-forming block with phenyl groups was synthesized by living anionic polymerization of phenyl ...

A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes

Norbornene can be polymerized by a variety of mechanisms, including insertion polymerization whereby the double bond is polymerized and the bicyclic nature of the monomer is conserved. The resulting polymer, polynorbornene, has a very high glass transition temperature, Tg, and interesting optical and electrical properties. However, the polymerization of functional norbornenes by this mechanism is complicated by the fact that the endo substituted norbornene monomer has, in general, a very low reactivity. Furthermore, the separation of the endo substituted monomer from the exo monomer is a tedious task. Here, we present a simple protocol for the polymerization of substituted norbornenes (endo:exo ca. 80:20) bearing either a carboxylic acid or a pendant double bond. The process does not require that both isomers be separated, and proceeds with low catalyst loadings (0.01 to 0.02 mol%). The polymer bearing pendant double bonds can be further transformed in high yield, to afford a polymer bearing pendant epoxy groups. These simple procedures can be applied to prepare polynorbornenes with a variety of functional groups, such as esters, alcohols, imides, double bonds, carboxylic acids, bromo-alkyls, aldehydes and anhydrides.

We describe the catalytic insertion polymerization of 5-norbornene-2-carboxylic acid and 5-vinyl-2-norbornene to form functional polymers with a very high glass transition temperature.

Norbornene can be polymerized by a variety of mechanisms, including insertion polymerization whereby the double bond is polymerized and the bicyclic ...

Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method

Carbonyl compounds present in bio-oils are known to be responsible for bio-oil property changes upon storage and during upgrading. Specifically, carbonyls cause an increase in viscosity (often referred to as &#39;aging&#39;) during storage of bio-oils. As such, carbonyl content has previously been used as a method of tracking bio-oil aging and condensation reactions with less variability than viscosity measurements. Additionally, carbonyls are also responsible for coke formation in bio-oil upgrading processes. Given the importance of carbonyls in bio-oils, accurate analytical methods for their quantification are very important for the bio-oil community. Potentiometric titration methods based on carbonyl oximation have long been used for the determination of carbonyl content in pyrolysis bio-oils. Here, we present a modification of the traditional carbonyl oximation procedures that results in less reaction time, smaller sample size, higher precision, and more accurate carbonyl determinations. While traditional carbonyl oximation methods occur at room temperature, the Faix method presented here occurs at an elevated temperature of 80 &#176;C.

Here we present a potentiometric titration technique for accurately quantifying carbonyl compounds in pyrolysis bio-oils.

Carbonyl compounds present in bio-oils are known to be responsible for bio-oil property changes upon storage and during upgrading. Specifically, carbonyls ...