This work was supported as part of the Advanced Materials for Energy-Water Systems (AMEWS) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. We gratefully acknowledge helpful discussions with Mark Stoykovich and Paul Nealey.

1. Fabrication of the transfer tool and drain chamber system
<ol>
	<li>Attached (Supplementary Files 1, 2) is the engineering drawing for the drain chamber assembly consisting of two parts: top and bottom. Model this device according to the specifications of the desired system (e.g., the outer diameter of the receiving substrate) and export as an STL file for 3D printing.</li>
	<li>For the top part, utilize a filament printer of choice and print in the lowest resolution possible, including scaffolding wherever necessary. Adhere to the recommended parameters of the printer. It is also recommended that the top part be printed using poly(lactic acid) (PLA) to minimize material shedding.</li>
	<li>For the bottom part, use an inkjet resin printer or filament printer with a build height as fine as 20 &#181;m. 
	NOTE: PLA is a suitable material which minimizes material shedding.</li>
	<li>Scrub and clean both parts with deionized water, ensuring the removal of any potential shedding material from the printing process. Sonication in deionized water is also recommended. Test the threading on the two parts to ensure a good fit.</li>
	<li>Complete the drain chamber with a size 117 neoprene O-ring and tubing of the parameters specified in the supporting documents (Supplementary Files 1, 2). A schematic of the entire drain chamber assembly is shown in Figure 1.</li>
	<li>Print the transfer tool using any filament printer at medium to fine resolution. There are two parts: clamp and loading arm. 
	NOTE: It is highly recommended that the transfer tool be printed using poly(lactic acid) (PLA), as other plastics can be poorly wetted and cause the wafer to become wet unexpectedly.</li>
	<li>Complete the clamp with a size 10 screw and then attach the clamp onto a laboratory jack.</li>
</ol>
2. Initial mechanized deposition and membrane lift-off from donor substrate
<ol>
	<li>Place a bare 25 mm-diameter AAO disc (or any arbitrary porous receiver substrate of choice) onto the bottom part of the drain chamber. Then, place the neoprene O-ring on top of the AAO disc and screw on the top part of the drain chamber.</li>
	<li>Rinse and/or sonicate the setup various times with deionized (DI) water. This helps to remove any dust and/or any remaining particulates from 3D printing.</li>
	<li>Place the piece of Si wafer with the transferable polymer stack (donor wafer) onto the lip of the transfer tool loading arm.</li>
	<li>Fill the drain chamber with 25 mL of DI water.</li>
	<li>Lower the laboratory jack so that the tool is dipped slowly into the entrance ramp of the drain chamber and that the donor silicon substrate is slowly submerged. Ensure that the wafer is submerged sufficiently for the membrane to completely delaminate and lift-off from the underlying donor substrate. 
	NOTE: Using a piece of Si wafer with no dust contamination will ensure easy separation from the donor substrate.</li>
	<li>Slowly raise the transfer tool out of the water and move it out of the way, making sure not to disturb the floating membrane.</li>
	<li>Coax the membrane into the opening of the chamber with tweezers. Placing the tweezer in water in front of membrane will guide it due to surface tension. Touching the floating membrane itself is not necessary and should be avoided.</li>
</ol>
3. Meniscus-guided transfer to receiver substrate with the drain chamber system
<ol>
	<li>Connect tubing to the outlet of the bottom part of the drain chamber. Attach this tubing to a 20 mL Luer-lock syringe.</li>
	<li>Obtain a syringe pump with withdrawing functionality. Place the syringe onto the pump and withdraw water at a rate of 1-2.5 mL/min until all the water has been drained out.</li>
	<li>After 10 min, the water should be completely removed from the drain chamber. If there is still any residual water within the chamber, reconnect the syringe and tubing and continue to withdraw any residual water.</li>
	<li>After complete drainage of the water, the membrane will now be placed at the center of the receiver substrate. Disconnect the drain chamber from the syringe pump and disassemble the drain chamber to remove the receiver substrate containing the membrane. 
	NOTE: The total process including set-up takes ~15 min. Reducing the working volume of water and increasing the drain rate can shorten this process.</li>
	<li>Allow the sample to dry completely at room temperature before further use in any application.</li>
</ol>

<ol>
	<li>Shah, A., Torres, P., Tscharner, R., Wyrsch, N., Keppner, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photovoltaic+technology:+the+case+for+thin-film+solar+cells.">Photovoltaic technology: the case for thin-film solar cells.</a> Science. 285 (5428), 692-698 (1999).</li><li>Kim, T. 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=Full-colour+quantum+dot+displays+fabricated+by+transfer+printing.">Full-colour quantum dot displays fabricated by transfer printing.</a> Nat. Photon. 5 (3), 176 (2011).</li><li>Nomura, K., 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=Room-temperature+fabrication+of+transparent+flexible+thin-film+transistors+using+amorphous+oxide+semiconductors.">Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors.</a> Nature. 432 (7016), 488 (2004).</li><li>Pirkle, A., 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+effect+of+chemical+residues+on+the+physical+and+electrical+properties+of+chemical+vapor+deposited+graphene+transferred+to+SiO2.">The effect of chemical residues on the physical and electrical properties of chemical vapor deposited graphene transferred to SiO2.</a> Applied Physics Letters. 99 (12), 122108-122110 (2011).</li><li>Chae, S. 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=Synthesis+of+large-area+graphene+layers+on+poly-nickel+substrate+by+chemical+vapor+deposition:+wrinkle+formation.">Synthesis of large-area graphene layers on poly-nickel substrate by chemical vapor deposition: wrinkle formation.</a> Advanced Materials. 21 (22), 2328-2333 (2009).</li><li>Zhu, 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=Structure+and+electronic+transport+in+graphene+wrinkles.">Structure and electronic transport in graphene wrinkles.</a> Nano Letters. 12 (7), 3431-3436 (2012).</li><li>Paronyan, T. M., Pigos, E. M., Chen, G., Harutyunyan, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+ripples+in+graphene+as+a+result+of+interfacial+instabilities.">Formation of ripples in graphene as a result of interfacial instabilities.</a> ACS Nano. 5 (12), 9619-9627 (2011).</li><li>Stadermann, 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=Fabrication+of+large-area+free-standing+ultrathin+polymer+films.">Fabrication of large-area free-standing ultrathin polymer films.</a> Journal of Visualized Experiments : JoVE. (100), e52832 (2015).</li><li>Zhou, 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=Fabrication+of+Nanoporous+Alumina+Ultrafiltration+Membrane+with+Tunable+Pore+Size+Using+Block+Copolymer+Templates.">Fabrication of Nanoporous Alumina Ultrafiltration Membrane with Tunable Pore Size Using Block Copolymer Templates.</a> Advanced Functional Materials. 27 (34), 1701756 (2017).</li><li>Meitl, M. A., 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=Transfer+printing+by+kinetic+control+of+adhesion+to+an+elastomeric+stamp.">Transfer printing by kinetic control of adhesion to an elastomeric stamp.</a> Nature Materials. 5 (1), 33 (2006).</li><li>Suk, J. 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=Transfer+of+CVD-grown+monolayer+graphene+onto+arbitrary+substrates.">Transfer of CVD-grown monolayer graphene onto arbitrary substrates.</a> ACS Nano. 5 (9), 6916-6924 (2011).</li><li>Chen, Y., Gong, X. L., Gai, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progress+and+Challenges+in+Transfer+of+Large-Area+Graphene+Films.">Progress and Challenges in Transfer of Large-Area Graphene Films.</a> Advanced Science. 3 (8), 1500343 (2016).</li></ol>

The authors have nothing to disclose.

While many of the steps listed in this protocol are crucial for the success of the thin film transfer, the nature of the custom-designed 3D printed drain chamber allows for broad flexibility, according to the user's specific requirements. For example, if the receiver substrate has a larger diameter than the 25-mm-diameter AAO discs utilized in this study, the drain chamber can be appropriately modified to fit the new specifications. However, there are certain aspects of the protocol that are necessary to ensure effective...

Thin film and nanomembrane-based devices have recently garnered wide interest due to their potential use in a broad range of applications, ranging from flexible photovoltaics and photonics, foldable displays, and wearable electronics1,2,3. A requirement for the fabrication of these various types of devices is the transfer of thin films to the surfaces of arbitrary substrates, which remains challenging due to the fragility of these films and the frequent production of macroscale defect structures, such as wrinkles, cracks, and tears, within the films after transfer4,5,6,7. Manual transfer by hand, tweezers, and wire loops are common methods of thin film transfer, but inevitably result in structural incongruities and plastic deformation8,9. Various types of thin film transfer methodologies have been explored such as: 1) polydimethylsiloxane (PDMS) stamp transfer, which involves the use of an elastomeric stamp to obtain the thin film from the donor substrate and subsequently transfer to the receiving substrate10, and 2) sacrificial layer transfer11, in which an etchant is used to selectively dissolve a sacrificial layer between the support substrate and the thin film, thereby lifting off the thin film. However, these techniques alone do not necessarily allow for thin film transfer without incurring damage to or defect formation within the thin films12.
Here, we present a novel, low-cost, and generalizable facile method based on sacrificial layer lift-off and meniscus-guided transfer within a custom-designed, 3D-printed drain chamber system, to mechanically place block copolymer (BCP) thin films onto the centers of porous substrates such as anodized aluminum oxide (AAO) discs with little-to-no incurred macroscale defect structures, such as wrinkles, tears, and cracks. In the present context, these transferred thin films can then be used as devices in water filtration studies, potentially after sequential infiltration synthesis (SIS) processing9. Image analysis of transferred films obtained from optical microscopy show that the meniscus-guided, drain-chamber system provides smooth, robust, and wrinkle-free samples. In addition, the images also demonstrate the system&#39;s ability to reliably place the thin film membranes onto the centers of the receiving substrates. Our results have significant implications for any type of device application requiring the transfer of thin film structures onto the surfaces of arbitrary porous substrates.

<table border="0" cellpadding="0" cellspacing="0" style="width:631px;" width="631">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:264px;">35% sodium polyacrylic acid solution</td>
			<td style="width:73px;">Sigma Aldrich</td>
			<td style="width:123px;">9003-01-4&#160;&#160;</td>
			<td style="width:171px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Amicon Stirred Cell model 8010 10mL</td>
			<td style="width:73px;">Millipore</td>
			<td style="width:123px;">5121</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:264px;">Anodized aluminum oxide, 0.2u thickness, 25mm diameter</td>
			<td style="width:73px;">Sigma Aldrich</td>
			<td style="width:123px;">WHA68096022</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">o ring neoprene 117</td>
			<td style="width:73px;">Grainger</td>
			<td>1BUV7</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Objet500 Connex3 3D Printer</td>
			<td style="width:73px;">Stratasys</td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Onshape 3D software</td>
			<td style="width:73px;">onshape</td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Polylactic acid filament</td>
			<td style="width:73px;">Ultimaker</td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">ultimaker3 3d filament printer</td>
			<td style="width:73px;">Ultimaker</td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Vero Family printable materials</td>
			<td style="width:73px;">Stratasys</td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

procedure for the transfer of polymer films onto porous substrates with minimized defects

The fabrication of devices containing thin film composite membranes necessitates the transfer of these films onto the surfaces of arbitrary support substrates. Accomplishing this transfer in a highly controlled, mechanized, and reproducible manner can eliminate the creation of macroscale defect structures (e.g., tears, cracks, and wrinkles) within the thin film that compromise device performance and the usable area per sample. Here, we describe a general protocol for the highly controlled and mechanized transfer of a polymeric thin film onto an arbitrary porous support substrate for eventual use as a water filtration membrane device. Specifically, we fabricate a block copolymer (BCP) thin film on top of a sacrificial, water-soluble poly(acrylic acid) (PAA) layer and silicon wafer substrate. We then utilize a custom-designed, 3D-printed transfer tool and drain chamber system to deposit, lift-off, and transfer the BCP thin film onto the center of a porous anodized aluminum oxide (AAO) support disc. The transferred BCP thin film is shown to be consistently placed onto the center of the support surface due to the guidance of the meniscus formed between the water and the 3D-printed plastic drain chamber. We also compare our mechanized transfer-processed thin films to those that have been transferred by hand with the use of tweezers. Optical inspection and image analysis of the transferred thin films from the mechanized process confirm that little-to-no macroscale inhomogeneities or plastic deformations are produced, as compared to the multitude of tears and wrinkles produced from manual transfer by hand. Our results suggest that the proposed strategy for thin film transfer can reduce defects when compared to other methods across many systems and applications.

The BCP membrane samples were fabricated according to the previously described procedure9. The samples were placed onto the lip of the loading arm of the 3D-printed transfer tool (Figure 1, left) and subsequently lowered, with a laboratory jack, onto the entrance ramp of the 3D-printed drain chamber tool (Figure 1, right). A sacrificial layer of poly(acrylic acid) (PAA) between the BCP membrane and underly...

Watch this Scientific Journal Video about Procedure for the Transfer of Polymer Films Onto Porous Substrates with Minimized Defects at JoVE.com

Procedure for the Transfer of Polymer Films Onto Porous Substrates with Minimized Defects

We present a procedure for highly controlled and wrinkle-free transfer of block copolymer thin films onto porous support substrates using a 3D-printed drain chamber. The drain chamber design is of general relevance to all procedures involving transfer of macromolecular films onto porous substrates, which is normally done by hand in an irreproducible fashion.

The fabrication of devices containing thin film composite membranes necessitates the transfer of these films onto the surfaces of arbitrary support ...

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Research

JoVE Journal

Engineering

6.5K Views.  University of Chicago. We present a procedure for highly controlled and wrinkle-free transfer of block copolymer thin films onto porous support substrates using a 3D-printed drain chamber. The drain chamber design is of general relevance to all procedures involving transfer of macromolecular films onto porous substrates, which is normally done by hand in an irreproducible fashion.

Video: Procedure for the Transfer of Polymer Films Onto Porous Substrates with Minimized Defects

Micropunching Lithography for Generating Micro- and Submicron-patterns on Polymer Substrates

Conducting polymers have attracted great attention since the discovery of high conductivity in doped polyacetylene in 19771. They offer the advantages of low weight, easy tailoring of properties and a wide spectrum of applications2,3. Due to sensitivity of conducting polymers to environmental conditions (e.g., air, oxygen, moisture, high temperature and chemical solutions), lithographic techniques present significant technical challenges when working with these materials4. For example, current photolithographic methods, such as ultra-violet (UV), are unsuitable for patterning the conducting polymers due to the involvement of wet and/or dry etching processes in these methods. In addition, current micro/nanosystems mainly have a planar form5,6. One layer of structures is built on the top surfaces of another layer of fabricated features. Multiple layers of these structures are stacked together to form numerous devices on a common substrate. The sidewall surfaces of the microstructures have not been used in constructing devices. On the other hand, sidewall patterns could be used, for example, to build 3-D circuits, modify fluidic channels and direct horizontal growth of nanowires and nanotubes.
A macropunching method has been applied in the manufacturing industry to create macropatterns in a sheet metal for over a hundred years. Motivated by this approach, we have developed a micropunching lithography method (MPL) to overcome the obstacles of patterning conducting polymers and generating sidewall patterns. Like the macropunching method, the MPL also includes two operations (Fig. 1): (i) cutting; and (ii) drawing. The "cutting" operation was applied to pattern three conducting polymers4, polypyrrole (PPy), Poly(3,4-ethylenedioxythiophen)-poly(4-styrenesulphonate) (PEDOT) and polyaniline (PANI). It was also employed to create Al microstructures7. The fabricated microstructures of conducting polymers have been used as humidity8, chemical8, and glucose sensors9. Combined microstructures of Al and conducting polymers have been employed to fabricate capacitors and various heterojunctions9,10,11. The "cutting" operation was also applied to generate submicron-patterns, such as 100- and 500-nm-wide PPy lines as well as 100-nm-wide Au wires. The "drawing" operation was employed for two applications: (i) produce Au sidewall patterns on high density polyethylene (HDPE) channels which could be used for building 3D microsystems12,13,14, and (ii) fabricate polydimethylsiloxane (PDMS) micropillars on HDPE substrates to increase the contact angle of the channel15.

A micropunching lithography approach is developed to generate micro- and submicron-patterns on top, sidewall and bottom surfaces of polymer substrates. It overcomes the obstacles of patterning conducting polymers and generating sidewall patterns. This method allows rapid fabrication of multiple features and is free of aggressive chemistry.

Conducting polymers have attracted great attention since the discovery of high conductivity in doped polyacetylene in 19771. They offer the advantages of ...

Integrating a Triplet-triplet Annihilation Up-conversion System to Enhance Dye-sensitized Solar Cell Response to Sub-bandgap Light

The poor response of dye-sensitized solar cells (DSCs) to red and infrared light is a significant impediment to the realization of higher photocurrents and hence higher efficiencies. Photon up-conversion by way of triplet-triplet annihilation (TTA-UC) is an attractive technique for using these otherwise wasted low energy photons to produce photocurrent, while not interfering with the photoanodic performance in a deleterious manner. Further to this, TTA-UC has a number of features, distinct from other reported photon up-conversion technologies, which renders it particularly suitable for coupling with DSC technology. In this work, a proven high performance TTA-UC system, comprising a palladium porphyrin sensitizer and rubrene emitter, is combined with a high performance DSC (utilizing the organic dye D149) in an integrated device. The device shows an enhanced response to sub-bandgap light over the absorption range of the TTA-UC sub-unit resulting in the highest figure of merit for up-conversion assisted DSC performance to date.

An integrated device, incorporating a dye-sensitized solar cell and triplet-triplet annihilation up-conversion unit was produced, affording enhanced light harvesting, from a wider section of the solar spectrum. Under modest irradiation levels a significantly enhanced response to low energy photons was demonstrated, yielding a record figure of merit for dye-sensitized solar cells.

The poor response of dye-sensitized solar cells (DSCs) to red and infrared light is a significant impediment to the realization of higher photocurrents ...

Preparation and Friction Force Microscopy Measurements of Immiscible, Opposing Polymer Brushes

Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low friction at the interface. Nevertheless, these systems can be sensitive to wear due to interdigitation of the opposing brushes. In a recent publication, we have shown via molecular dynamics simulations and atomic force microscopy experiments, that using an immiscible polymer brush system terminating the substrate and the slider surfaces, respectively, can eliminate such interdigitation. As a consequence, wear in the contacts is reduced. Moreover, the friction force is two orders of magnitude lower compared to traditional miscible polymer brush systems. This newly proposed system therefore holds great potential for application in industry. Here, the methodology to construct an immiscible polymer brush system of two different brushes each solvated by their own preferred solvent is presented. The procedure how to graft poly(N-isopropylacrylamide) (PNIPAM) from a flat surface and poly(methyl methacrylate) (PMMA) from an atomic force microscopy (AFM) colloidal probe is described. PNIPAM is solvated in water and PMMA in acetophenone. Via friction force AFM measurements, it is shown that the friction for this system is indeed reduced by two orders of magnitude compared to the miscible system of PMMA on PMMA solvated in acetophenone.

The methodology to perform friction force microscopy experiments for contacting brushes is presented: Two polymer brushes that are grafted from (a) substrates and (b) colloidal probes are slid to show that, by using two contacting immiscible brush systems, friction in sliding contacts is reduced compared to miscible brush systems.

Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low ...

SSVEP-based Experimental Procedure for Brain-Robot Interaction with Humanoid Robots

Brain-Robot Interaction (BRI), which provides an innovative communication pathway between human and a robotic device via brain signals, is prospective in helping the disabled in their daily lives. The overall goal of our method is to establish an SSVEP-based experimental procedure by integrating multiple software programs, such as OpenViBE, Choregraph, and Central software as well as user developed programs written in C++ and MATLAB, to enable the study of brain-robot interaction with humanoid robots.
This is achieved by first placing EEG electrodes on a human subject to measure the brain responses through an EEG data acquisition system. A user interface is used to elicit SSVEP responses and to display video feedback in the closed-loop control experiments. The second step is to record the EEG signals of first-time subjects, to analyze their SSVEP features offline, and to train the classifier for each subject. Next, the Online Signal Processor and the Robot Controller are configured for the online control of a humanoid robot. As the final step, the subject completes three specific closed-loop control experiments within different environments to evaluate the brain-robot interaction performance.
The advantage of this approach is its reliability and flexibility because it is developed by integrating multiple software programs. The results show that using this approach, the subject is capable of interacting with the humanoid robot via brain signals. This allows the mind-controlled humanoid robot to perform typical tasks that are popular in robotic research and are helpful in assisting the disabled.

The overall goal of this method is to establish an SSVEP-based experimental procedure by integrating multiple software programs to enable the study of brain-robot interaction with humanoid robots, which is prospective in assisting the sick and elderly as well as performing unsanitary or dangerous jobs.

Brain-Robot Interaction (BRI), which provides an innovative communication pathway between human and a robotic device via brain signals, is prospective in ...

Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step process that finishes with Negishi coupling. Negishi coupling is a cross-coupling process in which a chemical precursor is first lithiated, followed by transmetallation with ZnCl2. The resultant organozinc compound can be coupled to a dibrominated aromatic precursor to give the conjugated monomer. Polymer films can be prepared via electropolymerization of the monomer and characterized using cyclic voltammetry and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. Nanoparticles (NPs) are prepared via emulsion polymerization of the monomer using a two-surfactant system to yield an aqueous dispersion of the polymer NPs. The NPs are characterized using dynamic light scattering, electron microscopy, and UV-Vis-NIR-spectroscopy. Cytocompatibility of NPs is investigated using the cell viability assay. Finally, the NP suspensions are irradiated with a NIR laser to determine their effectiveness as potential materials for photothermal therapy (PTT).

A protocol is presented for the synthesis and preparation of nanoparticles consisting of electroactive polymers.

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step ...

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

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

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

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

Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present an advanced method for fabricating ultra-thin color films with improved characteristics. The proposed process addresses several fabrication issues, including large area processing. Specifically, the protocol describes a process for fabricating ultra-thin color films using an electron beam evaporator for oblique angle deposition of germanium (Ge) and gold (Au) on silicon (Si) substrates.&#160; Film porosity produced by the oblique angle deposition induces color changes in the ultra-thin film. The degree of color change depends on factors such as deposition angle and film thickness. Fabricated samples of the ultra-thin color films showed improved color tunability and color purity. In addition, the measured reflectance of the fabricated samples was converted into chromatic values and analyzed in terms of color. Our ultra-thin film fabricating method is expected to be used for various ultra-thin film applications such as flexible color electrodes, thin film solar cells, and optical filters. Also, the process developed here for analyzing the color of the fabricated samples is broadly useful for studying various color structures.

We present a detailed method for fabricating ultra-thin color films with improved characteristics for optical coatings. The oblique angle deposition technique using an electron beam evaporator allows improved color tunability and purity. Fabricated films of Ge and Au on Si substrates were analyzed by reflectance measurements and color information conversion.

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present ...

Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication

We have demonstrated that through the sulfurization of transition metal films such as molybdenum (Mo) and tungsten (W), large-area and uniform transition metal dichalcogenides (TMDs) MoS2 and WS2 can be prepared on sapphire substrates. By controlling the metal film thicknesses, good layer number controllability, down to a single layer of TMDs, can be obtained using this growth technique. Based on the results obtained from the Mo film sulfurized under the sulfur deficient condition, there are two mechanisms of (a) planar MoS2 growth and (b) Mo oxide segregation observed during the sulfurization procedure. When the background sulfur is sufficient, planar TMD growth is the dominant growth mechanism, which will result in a uniform MoS2 film after the sulfurization procedure. If the background sulfur is deficient, Mo oxide segregation will be the dominant growth mechanism at the initial stage of the sulfurization procedure. In this case, the sample with Mo oxide clusters covered with few-layer MoS2 will be obtained. After sequential Mo deposition/sulfurization and W deposition/sulfurization procedures, vertical WS2/MoS2 hetero-structures are established using this growth technique. Raman peaks corresponding to WS2 and MoS2, respectively, and the identical layer number of the hetero-structure with the summation of individual 2D materials have confirmed the successful establishment of the vertical 2D crystal hetero-structure. After transferring the WS2/MoS2 film onto a SiO2/Si substrate with pre-patterned source/drain electrodes, a bottom-gate transistor is fabricated. Compared with the transistor with only MoS2 channels, the higher drain currents of the device with the WS2/MoS2 hetero-structure have exhibited that with the introduction of 2D crystal hetero-structures, superior device performance can be obtained. The results have revealed the potential of this growth technique for the practical application of 2D crystals.

Through the sulfurization of pre-deposited transition metals, large-area and vertical 2D crystal hetero-structures can be fabricated. The film transferring and device fabrication procedures are also demonstrated in this report.

We have demonstrated that through the sulfurization of transition metal films such as molybdenum (Mo) and tungsten (W), large-area and uniform transition ...

Fabricating Reactive Surfaces with Brush-like and Crosslinked Films of Azlactone-Functionalized Block Co-Polymers

In this paper, fabrication methods that generate novel surfaces using the azlactone-based block co-polymer, poly (glycidyl methacrylate)-block-poly (vinyl dimethyl azlactone) (PGMA-b-PVDMA), are presented. Due to the high reactivity of azlactone groups towards amine, thiol, and hydroxyl groups, PGMA-b-PVDMA surfaces can be modified with secondary molecules to create chemically or biologically functionalized interfaces for a variety of applications. Previous reports of patterned PGMA-b-PVDMA interfaces have used traditional top-down patterning techniques that generate non-uniform films and poorly controlled background chemistries. Here, we describe customized patterning techniques that enable precise deposition of highly uniform PGMA-b-PVDMA films in backgrounds that are chemically inert or that have biomolecule-repellent properties. Importantly, these methods are designed to deposit PGMA-b-PVDMA films in a manner that completely preserves azlactone functionality through each processing step. Patterned films show well-controlled thicknesses that correspond to polymer brushes (~90 nm) or to highly crosslinked structures (~1-10 &#956;m). Brush patterns are generated using either the parylene lift-off or interface directed assembly methods described and are useful for precise modulation of overall chemical surface reactivity by adjusting either the PGMA-b-PVDMA pattern density or the length of the VDMA block. In contrast, the thick, crosslinked PGMA-b-PVDMA patterns are obtained using a customized micro-contact printing technique and offer the benefit of higher loading or capture of secondary material due to higher surface area to volume ratios. Detailed experimental steps, critical film characterizations, and trouble-shooting guides for each fabrication method are discussed.

Surface fabrication methods for patterned deposition of nanometer thick brushes or micron thick, crosslinked films of an azlactone block co-polymer are reported. Critical experimental steps, representative results, and limitations of each method are discussed. These methods are useful for creating functional interfaces with tailored physical features and tunable surface reactivity.

In this paper, fabrication methods that generate novel surfaces using the azlactone-based block co-polymer, poly (glycidyl methacrylate)-block-poly (vinyl ...

Radio Frequency Magnetron Sputtering of GdBa2Cu3O7&#8722;&#948;/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 (STO) Single-crystal Substrates

Here, we demonstrate a method of coating ferromagnetic La0.67Sr0.33MnO3 (LSMO) nanoparticles on (001) SrTiO3 (STO) single-crystal substrates by radio frequency (RF) magnetron sputtering. LSMO nanoparticles were deposited with diameters from 10 to 20 nm and heights between 20 and 50 nm. At the same time, (Gd) Ba2Cu3O7&#8722;&#948; ((Gd) BCO) films were fabricated on both undecorated and LSMO nanoparticle decorated STO substrates using RF magnetron sputtering. This report also describes the properties of GdBa2Cu3O7&#8722;&#948;/ La0.67Sr0.33MnO3 quasi-bilayer films structures (e.g., crystalline phase, morphology, chemical composition); magnetization, magneto-transport, and superconducting transport properties were also evaluated.

Radio Frequency Magnetron Sputtering of GdBa2Cu3O7ÃƒÂ¢Ã‹â€ &#039;ÃƒÅ½ ´/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 STO Single-crystal Substrates

Here, we present a protocol to grow LSMO nanoparticles and (Gd) BCO films on (001) SrTiO3 (STO) single-crystal substrates by radio frequency (RF)-sputtering.

Here, we demonstrate a method of coating ferromagnetic La0.67Sr0.33MnO3 (LSMO) nanoparticles on (001) SrTiO3 (STO) single-crystal substrates by radio ...