Name: solution blow spinning of polymeric nano-composite fibers for personal protective equipment
Uploaded: 2021-03-18T15:00:00
Description: Watch this Scientific Journal Video about Solution Blow Spinning of Polymeric Nano-Composite Fibers for Personal Protective Equipment at JoVE.com

The authors would like to acknowledge Mr. Dwight D. Barry for his important contributions for fabrication of the solution blow spinning apparatus. Zois Tsinas and Ran Tao would like to acknowledge funding from the National Institute of Standards and Technology under Awards # 70NANB20H007 and # 70NANB15H112, respectively.

NOTE: Details related to the equipment, instrumentation, and chemicals used in this section can be found in the Table of Materials. This entire protocol should first be reviewed and approved by the institutional safety department/personnel to ensure procedures and processes specific to the institution are adhered to.
1. Preparation of polymer solution using the appropriate solvent
NOTE: Consult manufacturer/supplier safety data sheets and the institut...

<ol>
	<li>Lee, B. 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=Penetration+failure+mechanisms+of+armor-grade+fiber+composites+under+impact.">Penetration failure mechanisms of armor-grade fiber composites under impact.</a> Journal of Composite Materials. 35 (18), 1605-1633 (2001).</li><li>Prevorsek, D. C., Kwon, Y. D., Chin, H. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+the+temperature+rise+in+the+projectile+and+extended+chain+polyethylene+fiber+composite+armor+during+ballistic+impact+and+penetration.">Analysis of the temperature rise in the projectile and extended chain polyethylene fiber composite armor during ballistic impact and penetration.</a> Polymer Engineering and Science. 34 (2), 141-152 (1994).</li><li>Park, A. D., Park, D., No Park, 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=.">.</a> U.S. Patent. , (2006).</li><li>No Park, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> U.S. Patent. , (1995).</li><li>Harpell, G. A., Prevorsek, D. C., Li, H. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flexible+multi-layered+armor.">Flexible multi-layered armor.</a> Patent No. WO/1989. , (1989).</li><li>Cena, C., 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=BSCCO+superconductor+micro/nanofibers+produced+by+solution+blow-spinning+technique.">BSCCO superconductor micro/nanofibers produced by solution blow-spinning technique.</a> Ceramics International. 43 (10), 7663-7667 (2017).</li><li>Miller, C. L., Stafford, G., Sigmon, N., Gilmore, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conductive+nonwoven+carbon+nanotube-PLA+composite+nanofibers+towards+wound+sensors+via+solution+blow+spinning.">Conductive nonwoven carbon nanotube-PLA composite nanofibers towards wound sensors via solution blow spinning.</a> IEEE Transactions on Nanobioscience. 18 (2), 244-247 (2019).</li><li>Iorio, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conformational+changes+on+PMMA+induced+by+the+presence+of+TiO+2+nanoparticles+and+the+processing+by+Solution+Blow+Spinning.">Conformational changes on PMMA induced by the presence of TiO 2 nanoparticles and the processing by Solution Blow Spinning.</a> Colloid and Polymer Science. 296 (3), 461-469 (2018).</li><li>Mart&#237;nez-Sanz, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antimicrobial+poly+(lactic+acid)-based+nanofibres+developed+by+solution+blow+spinning.">Antimicrobial poly (lactic acid)-based nanofibres developed by solution blow spinning.</a> Journal of Nanoscience and Nanotechnology. 15 (1), 616-627 (2015).</li><li>Wang, H., 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=Highly+flexible+indium+tin+oxide+nanofiber+transparent+electrodes+by+blow+spinning.">Highly flexible indium tin oxide nanofiber transparent electrodes by blow spinning.</a> ACS Applied Materials and Interfaces. 8 (48), 32661-32666 (2016).</li><li>Greenhalgh, R. 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=Hybrid+sol-gel+inorganic/gelatin+porous+fibres+via+solution+blow+spinning.">Hybrid sol-gel inorganic/gelatin porous fibres via solution blow spinning.</a> Journal of Materials Science. 52 (15), 9066-9081 (2017).</li><li>Gonzalez-Abrego, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesoporous+titania+nanofibers+by+solution+blow+spinning.">Mesoporous titania nanofibers by solution blow spinning.</a> Journal of Sol-Gel Science and Technology. 81 (2), 468-474 (2017).</li><li>Oliveira, J. E., Zucolotto, V., Mattoso, L. H., Medeiros, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi-walled+carbon+nanotubes+and+poly+(lactic+acid)+nanocomposite+fibrous+membranes+prepared+by+solution+blow+spinning.">Multi-walled carbon nanotubes and poly (lactic acid) nanocomposite fibrous membranes prepared by solution blow spinning.</a> Journal of Nanoscience and Nanotechnology. 12 (3), 2733-2741 (2012).</li><li>Medeiros, E. S., Glenn, G. M., Klamczynski, A. P., Orts, W. J., Mattoso, L. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solution+blow+spinning:+A+new+method+to+produce+micro-and+nanofibers+from+polymer+solutions.">Solution blow spinning: A new method to produce micro-and nanofibers from polymer solutions.</a> Journal of Applied Polymer Science. 113 (4), 2322-2330 (2009).</li><li>Vasireddi, R., 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=Solution+blow+spinning+of+polymer/nanocomposite+micro-/nanofibers+with+tunable+diameters+and+morphologies+using+a+gas+dynamic+virtual+nozzle.">Solution blow spinning of polymer/nanocomposite micro-/nanofibers with tunable diameters and morphologies using a gas dynamic virtual nozzle.</a> Scientific Reports. 9 (1), 1-10 (2019).</li><li>Tutak, W., 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=The+support+of+bone+marrow+stromal+cell+differentiation+by+airbrushed+nanofiber+scaffolds.">The support of bone marrow stromal cell differentiation by airbrushed nanofiber scaffolds.</a> Biomaterials. 34 (10), 2389-2398 (2013).</li><li>Daristotle, J. L., Behrens, A. M., Sandler, A. D., Kofinas, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+the+fundamental+principles+and+applications+of+solution+blow+spinning.">A review of the fundamental principles and applications of solution blow spinning.</a> ACS Applied Materials and Interfaces. 8 (51), 34951-34963 (2016).</li><li>Hofmann, E., 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=Microfluidic+nozzle+device+for+ultrafine+fiber+solution+blow+spinning+with+precise+diameter+control.">Microfluidic nozzle device for ultrafine fiber solution blow spinning with precise diameter control.</a> Lab on a Chip. 18 (15), 2225-2234 (2018).</li><li>Behrens, A. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+deposition+of+PLGA+nanofibers+via+solution+blow+spinning.">In situ deposition of PLGA nanofibers via solution blow spinning.</a> ACS Macro Letters. 3 (3), 249-254 (2014).</li><li>Vural, M., Behrens, A. M., Ayyub, O. B., Ayoub, J. J., Kofinas, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sprayable+elastic+conductors+based+on+block+copolymer+silver+nanoparticle+composites.">Sprayable elastic conductors based on block copolymer silver nanoparticle composites.</a> ACS Nano. 9 (1), 336-344 (2015).</li><li>Srinivasan, S., Chhatre, S. S., Mabry, J. M., Cohen, R. E., McKinley, G. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solution+spraying+of+poly+(methyl+methacrylate)+blends+to+fabricate+microtextured,+superoleophobic+surfaces.">Solution spraying of poly (methyl methacrylate) blends to fabricate microtextured, superoleophobic surfaces.</a> Polymer. 52 (14), 3209-3218 (2011).</li><li>Flory, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Principles of polymer chemistry. , (1953).</li><li>Palangetic, 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=Dispersity+and+spinnability:+Why+highly+polydisperse+polymer+solutions+are+desirable+for+electrospinning.">Dispersity and spinnability: Why highly polydisperse polymer solutions are desirable for electrospinning.</a> Polymer. 55 (19), 4920-4931 (2014).</li><li>Ying, Q., Chu, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Overlap+concentration+of+macromolecules+in+solution.">Overlap concentration of macromolecules in solution.</a> Macromolecules. 20 (2), 362-366 (1987).</li><li>Haro-P&#233;rez, C., Andablo-Reyes, E., D&#237;az-Leyva, P., Arauz-Lara, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microrheology+of+viscoelastic+fluids+containing+light-scattering+inclusions.">Microrheology of viscoelastic fluids containing light-scattering inclusions.</a> Physical Review E. 75 (4), 041505 (2007).</li><li>Thiele, J., 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=Early+development+drug+formulation+on+a+chip:+Fabrication+of+nanoparticles+using+a+microfluidic+spray+dryer.">Early development drug formulation on a chip: Fabrication of nanoparticles using a microfluidic spray dryer.</a> Lab on a Chip. 11 (14), 2362-2368 (2011).</li><li>Zhao, J., Xiong, W., Yu, N., Yang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+jetting+of+alginate+microfiber+in+atmosphere+based+on+a+microfluidic+chip.">Continuous jetting of alginate microfiber in atmosphere based on a microfluidic chip.</a> Micromachines. 8 (1), 8 (2017).</li><li>Jun, Y., Kang, E., Chae, S., Lee, 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=Microfluidic+spinning+of+micro-and+nano-scale+fibers+for+tissue+engineering.">Microfluidic spinning of micro-and nano-scale fibers for tissue engineering.</a> Lab on a Chip. 14 (13), 2145-2160 (2014).</li><li>Weng, B., Xu, F., Salinas, A., Lozano, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mass+production+of+carbon+nanotube+reinforced+poly+(methyl+methacrylate)+nonwoven+nanofiber+mats.">Mass production of carbon nanotube reinforced poly (methyl methacrylate) nonwoven nanofiber mats.</a> Carbon. 75, 217-226 (2014).</li><li>Barton, A. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solubility+parameters.">Solubility parameters.</a> Chemical Reviews. 75 (6), 731-753 (1975).</li></ol>

The method described herein provides a protocol for producing polymer elastomer nanocomposite fiber mats via a relatively new technique known as solution blow spinning. This technique allows the fabrication of fibers in the nanoscale and has several advantages over other well-established techniques, such as the electrospinning process, as it can be carried out under atmospheric pressure and room temperature27. Furthermore, SBS is not highly susceptible to local environmental changes (temperature o...

Many light-weight, ballistic, protective armor systems are currently constructed using high-modulus and high-strength polymeric fibers, such as oriented, ultra-high molar mass polyethylene fibers or aramids, which provide outstanding ballistic resistance1,2. These fibers are used in combination with an elastic resin material (binder) that can penetrate to the filament level and secure the fibers in a 0&#176;/90&#176; configuration to form a non-woven, unidirectional laminate. The percentage of the polymer elastomer resin (binder) should not exceed 13% of the total weight of the unidirectional laminate to maintain the structural integrity and antiballistic properties of the laminate structure3,4. The binder is a very important component of the armor as it keeps the high-strength fibers properly oriented and tightly packed within each laminate layer3. Elastomer materials commonly used as binders in body armor applications have very low tensile modulus (e.g., ~17.2 MPa at ~23 &#176;C), low glass transition temperature (preferably below -50 &#176;C), very high elongation at break (as high as 300%) and must demonstrate excellent adhesive properties5.
To improve the performance of these polymer elastomers, SBS was performed to create fibrous elastomer materials that can be used as binders in body armor applications. SBS is a relatively new, versatile technique allowing the use of different polymer/solvent systems and the creation of different end products6,7,8,9,10,11,12,13. This simple process involves the rapid (10x the rate of electrospinning) deposition of conformal fibers onto both planar and nonplanar substrates to fabricate sheets or webs of fibers that encompass&#160;nano and micro length scales14,15,16,17,18. SBS materials have numerous applications in medical products, air filters, protective equipment, sensors, optical electronics, and catalysts14,19,20. Developing small diameter fibers can drastically increase the surface area to volume ratio, which is very important for several applications, especially in the personal protective equipment field. The diameter and morphology of the fibers generated by SBS depend&#160;on the molar mass of the polymer, polymer concentration in the solution, viscosity of the solution, polymer solution flow rate, gas pressure, working distance, and diameter of the spray nozzle14,15,17.
An important characteristic of the SBS apparatus is the spray nozzle consisting of an inner and a concentric outer nozzle. The polymer dissolved in a volatile solvent is pumped through the inner nozzle while a pressurized gas flows through the outer nozzle. The high-velocity gas exiting the outer nozzle induces shearing of the polymer solution flowing through the inner nozzle. This forces the solution to form a conical shape when exiting the spray nozzle. When the surface tension at the tip of the cone is overcome, a fine stream of polymer solution is ejected, and the solvent rapidly evaporates causing polymer strands to coalesce and deposit as polymer fibers. The formation of a fibrous structure, as solvent evaporates, strongly depends on the polymer molar mass and the solution concentration. Fibers are formed by chain entanglement, when polymer chains in solution begin to overlap at a concentration known as the critical overlap concentration (c*). Therefore, it is necessary to work with polymer solutions above the c* of the polymer/solvent system selected. Also, an easy strategy to attain this is to choose polymers with relatively high molar mass. Polymers with higher molar mass have increased polymer relaxation times, which is directly related to an increase in the formation of fibrous structures, as described in the literature21. As many of the parameters used in SBS are strongly correlated, the goal of this work is to provide guidance to develop tunable, and flexible polymeric fiber nanocomposites to be used as alternatives for typical binder materials found in body armor applications by incorporating nanoparticles in the fibrous polymer-elastomer matrix.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>45 MM Toolmaker Vise</td>
			<td>Tormach Inc.</td>
			<td>32547</td>
			<td>To secure substrate onto the collector</td>
		</tr>
		<tr>
			<td>ARES-G2 Rheometer</td>
			<td>TA Instruments</td>
			<td>401000.501</td>
			<td>Rheometer</td>
		</tr>
		<tr>
			<td>Branson Ultrasonics M Series - Ultrasonic Cleaning Bath</td>
			<td>Fisher Scientific</td>
			<td>15-336-100</td>
			<td>To disperse nanoparticles</td>
		</tr>
		<tr>
			<td>Cadence Science&#160;Micro-Mate Interchangeable Syringe</td>
			<td>Fisher Scientific</td>
			<td>14-825-2A</td>
			<td>Glass Syringe 5mL in 1/5mL, Luer Lock Tip</td>
		</tr>
		<tr>
			<td>Chemical hood</td>
			<td>Any company</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Corning - Disposable Pasteur Glass Pipette</td>
			<td>Sigma Aldrich</td>
			<td>CLS7095D5X-200EA</td>
			<td>Non-Sterile</td>
		</tr>
		<tr>
			<td>DWK Life Sciences&#160;Wheaton - Glass Scintillation Vial</td>
			<td>Fisher Scientific</td>
			<td>03-341-25G</td>
			<td>20 mL with cap</td>
		</tr>
		<tr>
			<td>FEI Quanta 200 Scanning Electron Microscope (SEM)</td>
			<td>FEI</td>
			<td></td>
			<td>For imaging samples</td>
		</tr>
		<tr>
			<td>Iron Oxide Nanopowder/Nanoparticles</td>
			<td>US Research Nanomaterials, inc.</td>
			<td>US3320</td>
			<td>Fe3O4, 98%, 20-3- nm, Silicon oil Coated</td>
		</tr>
		<tr>
			<td>KD Scientific Legato 100 Single-Syringe Pump</td>
			<td>Sigma Aldrich</td>
			<td>Z401358-1EA</td>
			<td>Single syringe infusion pump</td>
		</tr>
		<tr>
			<td>Master Airbrush - Model S68</td>
			<td>TCP Global</td>
			<td>MAS S68</td>
			<td>Nozzle/needle diameter: 0.35 mm</td>
		</tr>
		<tr>
			<td>Mettler Toledo AB265-S/FACT Scale</td>
			<td>Cole-Parmer Scientific</td>
			<td>EW-11333-14</td>
			<td>For weighing polymer and&#160; Nanoparticles</td>
		</tr>
		<tr>
			<td>N2 Gas Regulator</td>
			<td>Any company</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Nanoenclosure</td>
			<td>Any company</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Optical Microscopy Glass Slides</td>
			<td>Fisher Scientific</td>
			<td>12-550-A3</td>
			<td>Used as a substrate for fiber mat deposition</td>
		</tr>
		<tr>
			<td>OSP Slotted Bob, 33 mm</td>
			<td>TA Instruments</td>
			<td>402796.902</td>
			<td>Bob, upper geometry</td>
		</tr>
		<tr>
			<td>OSP Slotted Double Gap Cup, 34 mm</td>
			<td>TA Instruments</td>
			<td>402782.901</td>
			<td>Double wall cup, lower geometry</td>
		</tr>
		<tr>
			<td>Oxford BenchMate Digital Vortex Mixer</td>
			<td>Pipette</td>
			<td>VM-D</td>
			<td>Rated up to 4,200 rpm, for mixing solutions</td>
		</tr>
		<tr>
			<td>Oxford Benchmate Tube Roller</td>
			<td>Pipette</td>
			<td>OTR-24DR</td>
			<td>Sample mixer/rotator</td>
		</tr>
		<tr>
			<td>Polystyrene-block-polybutadiene-block-polystyrene</td>
			<td>Sigma Aldrich</td>
			<td>432490-1KG</td>
			<td>styrene 30 wt. %, Mw ~ 185,000 g/mol</td>
		</tr>
		<tr>
			<td>SEM Pin Stub Specimen Mount</td>
			<td>Ted Pella Inc.</td>
			<td>16119</td>
			<td>18 mm diameter x 8 mm height</td>
		</tr>
		<tr>
			<td>Spatula</td>
			<td>VWR</td>
			<td>82027-532</td>
			<td>To load test materials</td>
		</tr>
		<tr>
			<td>Tetrahydrofuran (THF)</td>
			<td>Fisher Scientific</td>
			<td>T425-1</td>
			<td>solvent, HPLC grade</td>
		</tr>
		<tr>
			<td>TRIOS</td>
			<td>TA Instruments</td>
			<td>v4.3.1.39215</td>
			<td>Rheometer software</td>
		</tr>
	</tbody>
</table>

solution blow spinning of polymeric nano-composite fibers for personal protective equipment

Light-weight, protective armor systems typically consist of high modulus (&#62;109 MPa) and high-strength polymeric fibers held in place with an elastic resin material (binder) to form a non-woven, unidirectional laminate. While significant efforts have focused on improving the mechanical properties of the high-strength fibers, little work has been undertaken to improve the properties of the binder materials. To improve the performance of these elastomeric polymer binders, a relatively new and simple fabrication process, known as solution blow spinning, was used. This technique is capable of producing sheets or webs of fibers with average diameters ranging from the nanoscale to the microscale. To achieve this, a solution blow spinning (SBS) apparatus has been designed and built in the laboratory to fabricate non-woven fiber mats from polymer elastomer solutions.
In this study, a commonly used binder material, a styrene-butadiene-styrene block-co-polymer dissolved in tetrahydrofuran, was used to produce nanocomposite fiber mats by adding metallic nanoparticles (NPs), such as iron oxide NPs, that were encapsulated with silicon oil and thus incorporated in the fibers formed via the SBS process. The protocol described in this work will discuss the effects of the various critical parameters involved in the SBS process, including the polymer molar mass, the selection of the thermodynamically appropriate solvent, the polymer concentration in solution, and the carrier gas pressure to assist others in performing similar experiments, as well as provide guidance to optimize the configuration of the experimental setup. The structural integrity and morphology of the resultant non-woven fiber mats were examined using scanning electron microscopy (SEM) and elemental X-ray analysis via energy-dispersive X-ray spectroscopy (EDS). The goal of this study is to evaluate the effects of the various experimental parameters and material selections to optimize the structure and morphology of the SBS fiber mats.

In this study, non-woven fiber mats consisting of poly(styrene-butadiene-styrene) fibers in the nano- and micro-scale, were synthesized with and without the presence of iron oxide NPs. To form fibers, the SBS parameters must be carefully selected for the polymer/solvent system used. The molar mass of the dissolved polymer and the solution concentration are critical in controlling the morphology of the structures produced by the SBS process. In this study, a poly(styrene-butadiene-styrene) block-co-polymer (styrene 30 wt....

Watch this Scientific Journal Video about Solution Blow Spinning of Polymeric Nano-Composite Fibers for Personal Protective Equipment at JoVE.com

Solution Blow Spinning of Polymeric Nano-Composite Fibers for Personal Protective Equipment

The primary goal of this study is to describe a protocol to prepare polymeric fiber mats with consistent morphology via solution blow spinning (SBS). We aim to use SBS to develop novel, tunable, flexible polymeric fiber nanocomposites for various applications, including protective materials, by incorporating nanoparticles in a polymer-elastomer matrix.

Light-weight, protective armor systems typically consist of high modulus (&#62;109 MPa) and high-strength polymeric fibers held in place with an elastic ...

This self protocol covers some of the most important parameters and steps involved in solution blow spinning of polymeric nano composite fibers including polymer molar mass selection of thermodynamically appropriate solvents, polymeric concentration in solution, incorporation of nano materials, carrier gas pressure, and working distance. SPS is a relatively new technique that offers great versatility with respect to the polymer solvent system and the end product. Furthermore, it can be used to rapidly deposit formal fibers onto both planar and non-planar substrates and create sits or webs of fibers of both the nano and microscale diameters.The goal of this work is to provide guidance to develop tunable and flexible polymeric fiber nano composites that can be used as alternatives for typical binder materials found in body armor applications by incorporating nano particles in the fiber's polymer elastomer matrix. Currently, there are no commercially available systems or standard operating procedures to perform a solution blow spinning on tuneable polymeric nano composite fibers. The demonstration of our particle and apparatus could help others to effectively develop their own process for their application.To begin, transfer the desired amount of the dry polymer into a clean 20 milliliter borosilicate glass vial using a small spatula. Place the vial into the chemical fume hood and add approximately 10 milliliters of tetrahydrofuran to achieve a 200 milligrams per milliliter concentration. Then close the vial and place it on the mixer or rotator.Add dry iron oxide nanoparticle powder into a clean 20 milliliter glass vial. Then add 10 milliliters of tetrahydrofuran into the vial and close it. Thoroughly agitate the sample on the vortex mixer until the nanoparticles become invisible at the bottom of the vial and then sonicate the sample for approximately 30 minutes with a two to five minute interval between each sonication, to ensure the complete dispersion of the nanoparticles, and to avoid the sample heating.Add the polymer into the nanoparticle dispersion inside the chemical hood and seal the vial. Then mix it on the rotator at 70 RPM for 60 minutes at room temperature until the polymer completely dissolves. Adjust the height and angle of the airbrush to align with the center of the glass microscope slide attached to the collector and secured in place.Ensure the gas cylinder is properly secured to its wall mount, and connect the gas inlet of the airbrush to the nitrogen pressurized gas cylinder. Turn on the main valve of the gas cylinder and slowly adjust the pressure to achieve the desired flow. Then close the main valve.Secure the substrate on the collector using the equipped vice and adjust the height of the collector to align perpendicular to the spray direction and pattern of the airbrush to deposit the material on the substrate. Identify the optimal working distance by sliding the collector to its furthest position away from the airbrush nozzle. Transfer the polymer nanoparticle solvent mixture into a dissolved gas analysis borosilicate glass syringe equipped with a stainless steel needle.Remove any air bubbles from the sample by holding the syringe with the needle pointing up and tapping the syringe gently then slowly depress the plunger to displace any excess air. Detach the needle, attach the syringe to the syringe pump unit and secure the syringe. Connect the PTFE tubing coming from the outlet of the syringe to the appropriate inlet on the airbrush and select the desired injection rate from the syringe pump unit menu.Open the main valve on the nitrogen gas cylinder for the nitrogen gas to flow through the airbrush and initiate the spraying process by starting the syringe pump unit to dispense the polymer nanoparticle solvent mixture. Observe the spraying pattern and ensure that there are no clogs. Incrementally increase or decrease the injection rate until the solution is spraying freely.Adjust the position of the collector for solvent evaporation by sliding it towards the airbrush until the desired amount of the material is deposited on the substrate. Then stop the syringe pump unit and close the main valve of the nitrogen gas cylinder. At the critical concentration the dissolved polymer coils start to overlap each other and cause entanglement.The calculated and experimentally predicted values of the critical concentration were similar. Therefore, a polymer concentration above the critical concentration was used for the solution blow spinning process. The effect of different polymer concentrations on the fiber mat morphology was studied, and it was observed that undesired polymer beads were present at lower and near the critical overlap polymer concentrations.Pristine and morphologically smooth fibers were obtained at polymer concentrations above the critical concentration. At low magnification the fiber mat generated from a high polymer concentration showed the presence of individual and cylindrically shaped fibers with minimal beads or fiber welding. Higher magnification confirms the absence of polymer beads.The effect of gas pressure on fiber morphology was also studied. As pressure increases the fiber diameter decreases while very high pressure results in large polymer beads and welded fibers. The presence of iron oxide nanoparticles within the polymer fibers was determined using back scattered electron analysis.The elemental analysis further indicated the presence of iron oxide nanoparticles Selection of an appropriate solvent, as well as the molar mass of the polymer in its concentration and solution are some of the most critical parameters that can dictate success or failure of this protocol. The methods described in this protocol can be applied to develop polymeric fiber nano composites for various other fields and applications including biomaterials, polymer based conductive materials, filtration devices, and others.

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Research

JoVE Journal

Engineering

Development of Whispering Gallery Mode Polymeric Micro-optical Electric Field Sensors

Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The optical modes are frequently referred to as "whispering gallery modes" (WGM) or "morphology dependent resonances" (MDR) and exhibit high optical quality factors. Some proposed applications of micro-cavity optical resonators are in spectroscopy1, micro-cavity laser technology2, optical communications3-6 as well as sensor technology. The WGM-based sensor applications include those in biology7, trace gas detection8, and impurity detection in liquids9. Mechanical sensors based on microsphere resonators have also been proposed, including those for force10,11, pressure12, acceleration13 and wall shear stress14. In the present, we demonstrate a WGM-based electric field sensor, which builds on our previous studies15,16. A candidate application of this sensor is in the detection of neuronal action potential.
The electric field sensor is based on polymeric multi-layered dielectric microspheres. The external electric field induces surface and body forces on the spheres (electrostriction effect) leading to elastic deformation. This change in the morphology of the spheres, leads to shifts in the WGM. The electric field-induced WGM shifts are interrogated by exciting the optical modes of the spheres by laser light. Light from a distributed feedback (DFB) laser (nominal wavelength of ~ 1.3 &mu;m) is side-coupled into the microspheres using a tapered section of a single mode optical fiber. The base material of the spheres is polydimethylsiloxane (PDMS). Three microsphere geometries are used: (1) PDMS sphere with a 60:1 volumetric ratio of base-to-curing agent mixture, (2) multi layer sphere with 60:1 PDMS core, in order to increase the dielectric constant of the sphere, a middle layer of 60:1 PDMS that is mixed with varying amounts (2% to 10% by volume) of barium titanate and an outer layer of 60:1 PDMS and (3) solid silica sphere coated with a thin layer of uncured PDMS base. In each type of sensor, laser light from the tapered fiber is coupled into the outermost layer that provides high optical quality factor WGM (Q ~ 106). The microspheres are poled for several hours at electric fields of ~ 1 MV/m to increase their sensitivity to electric field.

A high-sensitivity photonic micro sensor was developed for electric field detection. The sensor exploits the optical modes of a dielectric sphere. Changes in the external electric field perturb the sphere morphology leading to shifts in its optical modes. The electric field strength is measured by monitoring these optical shifts.

Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The ...

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.

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

Mechanical Expansion of Steel Tubing as a Solution to Leaky Wellbores

Wellbore cement, a procedural component of wellbore completion operations, primarily provides zonal isolation and mechanical support of the metal pipe (casing), and protects metal components from corrosive fluids. These are essential for uncompromised wellbore integrity. Cements can undergo multiple forms of failure, such as debonding at the cement/rock and cement/metal interfaces, fracturing, and defects within the cement matrix. Failures and defects within the cement will ultimately lead to fluid migration, resulting in inter-zonal fluid migration and premature well abandonment. Currently, there are over 1.8 million operating wells worldwide and over one third of these wells have leak related problems defined as Sustained Casing Pressure (SCP)1. 
The focus of this research was to develop an experimental setup at bench-scale to explore the effect of mechanical manipulation of wellbore casing-cement composite samples as a potential technology for the remediation of gas leaks. 
The experimental methodology utilized in this study enabled formation of an impermeable seal at the pipe/cement interface in a simulated wellbore system. Successful nitrogen gas flow-through measurements demonstrated that an existing microannulus was sealed at laboratory experimental conditions and fluid flow prevented by mechanical manipulation of the metal/cement composite sample. Furthermore, this methodology can be applied not only for the remediation of leaky wellbores, but also in plugging and abandonment procedures as well as wellbore completions technology, and potentially preventing negative impacts of wellbores on subsurface and surface environments.

This article reports on a laboratory scale investigation of an existing field procedure and its adaptation for sealing of leaky wellbores. It consists of mechanical expansion of metal pipe, which results in an improved metal/cement bond, ultimate sealing of hydraulic pathways and prevention of gas leaks caused by the presence of a microannular channel.

Wellbore cement, a procedural component of wellbore completion operations, primarily provides zonal isolation and mechanical support of the metal pipe ...

Writing Bragg Gratings in Multicore Fibers

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers.

We describe a technique for inscribing identical fiber Bragg gratings into each core of a multicore fiber. This is achieved by introducing an additional surface into the optical path to mitigate lensing by the curved surface of the fiber cladding.

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong ...

How to Build a Vacuum Spring-transport Package for Spinning Rotor Gauges

The spinning rotor gauge (SRG) is a high-vacuum gauge often used as a secondary or transfer standard for vacuum pressures in the range of 1.0 x 10-4 Pa to 1.0 Pa. In this application, the SRGs are frequently transported to laboratories for calibration. Events can occur during transportation that change the rotor surface conditions, thus changing the calibration factor. To assure calibration stability, a spring-transport mechanism is often used to immobilize the rotor and keep it under vacuum during transport. It is also important to transport the spring-transport mechanism using packaging designed to minimize the risk of damage during shipping. In this manuscript, a detailed description is given on how to build a robust spring-transport mechanism and shipping container. Together these form a spring-transport package. The spring-transport package design was tested using drop-tests and the performance was found to be excellent. The present spring-transport mechanism design keeps the rotor immobilized when experiencing shocks of several hundred g (g = 9.8 m/sec2 and is the acceleration due to gravity), while the shipping container assures that the mechanism will not experience shocks greater than about 100 g during common shipping mishaps (as defined by industry standards).

Here we describe how to build a robust spring-transport mechanism for a spinning rotor gauge. This device securely immobilizes the rotor and keeps it under vacuum during transportation. We also describe packaging that minimizes the risk of damage during transport. Tests show our design works for typical shocks during transport.

The spinning rotor gauge (SRG) is a high-vacuum gauge often used as a secondary or transfer standard for vacuum pressures in the range of 1.0 x 10-4 Pa to ...

Fabrication of Fully Solution Processed Inorganic Nanocrystal Photovoltaic Devices

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal inks. For the photoactive absorber layer, colloidal CdTe and CdSe nanocrystals (3-5 nm) are synthesized using an inert hot injection technique and cleaned with precipitations to remove excess starting reagents. Similarly, gold nanocrystals (3-5 nm) are synthesized under ambient conditions and dissolved in organic solvents. In addition, precursor solutions for transparent conductive indium tin oxide (ITO) films are prepared from solutions of indium and tin salts paired with a reactive oxidizer. Layer-by-layer, these solutions are deposited onto a glass substrate following annealing (200-400 &#176;C) to build the nanocrystal solar cell (glass/ITO/CdSe/CdTe/Au). Pre-annealing ligand exchange is required for CdSe and CdTe nanocrystals where films are dipped in NH4Cl:methanol to replace long-chain native ligands with small inorganic Cl- anions. NH4Cl(s) was found to act as a catalyst for the sintering reaction (as a non-toxic alternative to the conventional CdCl2(s) treatment) leading to grain growth (136&#177;39 nm) during heating. The thickness and roughness of the prepared films are characterized with SEM and optical profilometry. FTIR is used to determine the degree of ligand exchange prior to sintering, and XRD is used to verify the crystallinity and phase of each material. UV/Vis spectra show high visible light transmission through the ITO layer and a red shift in the absorbance of the cadmium chalcogenide nanocrystals after thermal annealing. Current-voltage curves of completed devices are measured under simulated one sun illumination. Small differences in deposition techniques and reagents employed during ligand exchange have been shown to have a profound influence on the device properties. Here, we examine the effects of chemical (sintering and ligand exchange agents) and physical treatments (solution concentration, spray-pressure, annealing time and annealing temperature) on photovoltaic device performance.

This protocol describes the synthesis and solution deposition of inorganic nanocrystals layer by layer to produce thin film electronics on non-conductive surfaces. Solvent-stabilized inks can produce complete photovoltaic devices on glass substrates via spin and spray coating following post-deposition ligand exchange and sintering.

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal ...

Experimental Procedure for Warm Spinning of Cast Aluminum Components

High performance, cast aluminum automotive wheels are increasingly being incrementally formed via flow forming/metal spinning at elevated temperatures to improve material properties. With a wide array of processing parameters which can affect both the shape attained and resulting material properties, this type of processing is notoriously difficult to commission. A simplified, light-duty version of the process has been designed and implemented for full-size automotive wheels. The apparatus is intended to assist in understanding the deformation mechanisms and the material response to this type of processing. An experimental protocol has been developed to prepare for, and subsequently perform forming trials and is described for as-cast A356 wheel blanks. The thermal profile attained, along with instrumentation details are provided. Similitude with full-scale forming operations which impart significantly more deformation at faster rates is discussed.

An experimental protocol for instrumented warm rotary forming of cast aluminum alloys employing a bespoke industrially scaled apparatus is presented. Experimental considerations including thermal and mechanical effects are discussed, as well as similitude with full-scale processing of automotive wheels.

High performance, cast aluminum automotive wheels are increasingly being incrementally formed via flow forming/metal spinning at elevated temperatures to ...

Scalable Solution-processed Fabrication Strategy for High-performance, Flexible, Transparent Electrodes with Embedded Metal Mesh

Here, the authors report the embedded metal-mesh transparent electrode (EMTE), a new transparent electrode (TE) with a metal mesh completely embedded in a polymer film. This paper also presents a low-cost, vacuum-free fabrication method for this novel TE; the approach combines lithography, electroplating, and imprint transfer (LEIT) processing. The embedded nature of the EMTEs offers many advantages, such as high surface smoothness, which is essential for organic electronic device production; superior mechanical stability during bending; favorable resistance to chemicals and moisture; and strong adhesion with plastic film. LEIT fabrication features an electroplating process for vacuum-free metal deposition and is favorable for industrial mass production. Furthermore, LEIT allows for the fabrication of metal mesh with a high aspect ratio (i.e., thickness to linewidth), significantly enhancing its electrical conductance without adversely losing optical transmittance. We demonstrate several prototypes of flexible EMTEs, with sheet resistances lower than 1 &#937;/sq and transmittances greater than 90%, resulting in very high figures of merit (FoM) &#8211; up to 1.5 x 104 &#8211; which are amongst the best values in the published literature.

This protocol describes a solution-based fabrication strategy for high-performance, flexible, transparent electrodes with fully-embedded, thick metal mesh. Flexible transparent electrodes fabricated by this process demonstrate among the highest reported performances, including ultra-low sheet resistance, high optical transmittance, mechanical stability under bending, strong substrate adhesion, surface smoothness, and environmental stability.

Here, the authors report the embedded metal-mesh transparent electrode (EMTE), a new transparent electrode (TE) with a metal mesh completely embedded in a ...

New Application of an Atmospheric Pressure Plasma Jet as a Neuro-protective Agent Against Glucose Deprivation-induced Injury of SH-SY5Y Cells

The atmospheric pressure plasma jet (APPJ) has attracted the attention of many researchers from multiple disciplines in recent years because its emissions include multiple types of reactive nitrogen species (RNS) and reactive oxygen species (ROS). Our previous study has shown the cytoprotective effect of the APPJ against oxidative stress-induced injuries. The aim of the present study is to provide a detailed in vitro treatment protocol regarding the neuroprotective applications of helium APPJs on glucose deprivation-induced injury in SH-SY5Y cells. The SH-SY5Y human neuroblastoma-derived cell line was maintained in RPMI 1640 medium supplemented with 15% fetal calf serum. The culture medium was then changed to RPMI 1640 without glucose before APPJ treatment. After a 1 h incubation in a cell incubator, cell viability was determined using Cell Counting Kit 8. The results showed that, compared to the glucose deprivation group, cells treated with APPJ exhibited significantly increased cell viability in a dose-dependent manner, with 8 s/well observed as an optimal dose. Meanwhile, helium flow had no effect on the glucose deprivation-induced cell impairment. Our results indicated that APPJ could be potentially used as a treatment method for the diseases in the central nervous system related to glucose deprivation. This protocol could also be used as a cytoprotective application for other cells with different impairments, but the cell culture and APPJ treatment conditions should be readjusted, and the treatment dose must be relatively low.

A protocol for the neuroprotective application of low-dose atmospheric pressure plasma treatment on glucose deprivation-induced SH-SY5Y injuries.

The atmospheric pressure plasma jet (APPJ) has attracted the attention of many researchers from multiple disciplines in recent years because its emissions ...

Flow-assisted Dielectrophoresis: A Low Cost Method for the Fabrication of High Performance Solution-processable Nanowire Devices

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of nanowires. DEP is used for nanowire analysis, characterization, and for solution-based fabrication of semiconducting devices. The method works by applying an alternating electric field between metallic electrodes. The nanowire formulation is then dropped onto the electrodes which are on an inclined surface to create a flow of the formulation using gravity. The nanowires then align along the gradient of the electric field and in the direction of the liquid flow. The frequency of the field can be adjusted to select nanowires with superior conductivity and lower trap density. 
In this work, flow-assisted DEP is used to create nanowire field effect transistors. Flow-assisted DEP has several advantages: it allows selection of nanowire electrical properties; control of nanowire length; placement of nanowires in specific areas; control of orientation of nanowires; and control of nanowire density in the device. 
The technique can be expanded to many other applications such as gas sensors and microwave switches. The technique is efficient, quick, reproducible, and it uses a minimal amount of dilute solution making it ideal for the testing of novel nanomaterials. Wafer scale assembly of nanowire devices can also be achieved using this technique, allowing large numbers of samples for testing and large-area electronic applications.

In this paper, flow assisted dielectrophoresis is demonstrated for the self-assembly of nanowire devices. The fabrication of a silicon nanowire field effect transistor is shown as an example.

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of ...