This research was supported by Kansas State University. A portion of this research was conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences and U.S. Department of Energy.

1. PGMA-b-PVDMA Synthesis20
<ol>
	<li>Synthesis of PGMA macro-chain transfer agent (Macro-CTA)
	<ol>
		<li>Use a 250-mL round-bottom reaction &#64258;ask equipped with a polytetrafluoroethylene-coated magnetic stir bar.</li>
		<li>Combine 14.2 g of glycidyl methacrylate GMA (142.18 g/mol) with 490.8 mg of 2-cyano-2-propyl dodecyl trithiocarbonate (CPDT) (346.63 g/mol), and 87.7 mg of 2,2&#8242;-azobis (4-methoxy-2,4-dimethyl valeronitrile) (V-70) (308.43 g/mol) (molar ratio of CPDT: V-70 = 5:1), and benzene (100 mL) into air free round bottom flask.</li>
		<li>Degas the reaction mixture using argon and stir for 30 min. Subsequently put the solution in a temperature-controlled oil bath at 30 &#176;C and react for 18 h. 
		NOTE: The targeted molecular weight for the Macro-CTA is 10,000 g/mol. 18 hours was determined to be the time necessary to reach reasonable conversion. The color of the polymer solution is transparent light yellow.</li>
		<li>After 18 h, terminate the reaction by submerging the round bottom flask in liquid N2.</li>
		<li>Precipitate the polymer by pouring the light-yellow solution of polymer/benzene (~100 mL) into 400 mL of hexane.</li>
		<li>Stir the mixture for 5 min. Precipitate will be settled at the bottom of the beaker and is recovered by filtration.</li>
		<li>Dry the precipitate overnight under vacuum. Then dilute it in 400 mL of tetrahydrofuran (THF). Re-precipitate in hexane.</li>
		<li>Dry this new precipitate again with argon overnight. 
		NOTE: Macro-CTA is a fine yellow powder. The product yield of the reaction will be ~43.8%. The Mn of the PGMA Macro-CTA is 7,990 g/mol with a polydispersity (PDI) of 1.506 (MW = 12,030 g/mol).</li>
	</ol>
	</li>
	<li>Synthesis of PGMA-b-PVDMA
	<ol>
		<li>Fractionally distill the VDMA under reduced pressure, and reserve the middle fraction (~70%) for use. 
		NOTE: This is required to remove polymerization inhibitor. The distillation apparatus is attached to a Schlenk line and the air seal valve is partially opened to the vacuum line. Minimal heat is applied using a varistat and heating mantle until the VDMA monomer begins distilling over at a rate of 1 drop per second.</li>
		<li>Combine the 2-Vinyl-4,4- dimethyl azlactone (VDMA) (139.15 g/mol)monomer (10.436 g) with the PGMA-macroCTA (1.669 g), V-70 (14.5 mg; molar ratio of PGMA-macroCTA: V-70 = 3:1) and benzene (75.0 mL) in a single-neck 250-mL round-bottom reaction &#64258;ask equipped with a Teflon-coated magnetic stir bar. 
		NOTE: Molecular weight information, PVDMA: 139.15 g/mol, PGMA-macroCTA: 12,030 g/mol, Benzene: 78.11 g/mol.</li>
		<li>Degas the mixture with high purity argon and stir for 30 min, and then put in oil bath at 32 &#176;C for 18 h.</li>
		<li>Terminate the reaction by submerging the round bottom flask in liquid N2.</li>
		<li>Precipitate the polymer three times into hexane and dry it at room temperature under vacuum.</li>
		<li>Characterize the molecular weight and PDI of the product by using size exclusion chromatography (S) (see the Table of Materials) according to the procedure in Lokitz et al.20.The size exclusion chromatograph (S) is equipped with three PLgel 5 &#181;m mixed-C columns (300 x 7.5 mm) in series, a refractive index detector (Wavelength= 880 nm), a photodiode array detector, multi-angle light scattering (MALS) detector (Wavelength= 660 nm), and a viscometer (see the Table of Materials). 
		NOTE: All experiments performed in this manuscript used product with PGMA and PVDMA block lengths of 56 and 175, respectively. The molecular weight of the block copolymer was 37,620 g/mol and the PDI was 1.16.</li>
	</ol>
	</li>
</ol>
2. Generation of Parylene Stencil Patterns Over Silicon Substrates
<ol>
	<li>Parylene coating
	<ol>
		<li>Sonicate silicon wafers in 50% wt. acetone in water for 5 min followed by sonication in 50% wt. isopropanol (IPA) in water for 5 min.</li>
		<li>Rinse silicon wafers with deionized (DI) water and blow dry with nitrogen gas.</li>
		<li>Deposit 80 nm and 1 &#181;m thick parylene N on 4-inch silicon wafers using a parylene coater (see the Table of Materials). 
		NOTE: Characterize the thickness of parylene films by using a surface profilometer (see the Table of Materials).
		<ol>
			<li>Calibrate parylene film thickness with parylene dimer mass for each individual parylene coating system. 
			NOTE: In the current system, ~80 mg and ~1000 mg parylene N dimer was required to obtain 80 nm and 1 &#181;m film thickness, respectively (based on the calibration curve obtained).</li>
			<li>Use the following settings during operation of the parylene coater: pressure: 80 mTorr, duration: 1 h, furnace temperature: 690 &#176;C, vaporizer temperature: 160 &#176;C.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Photolithography
	<ol>
		<li>Bake wafers in an oven at 100 &#176;C for 20 min; then let wafers sit for another 3 min at room temperature. 
		NOTE: Additional wait time improves adhesion of the photoresist.</li>
		<li>Add 2 mL of positive photoresist&#160;(see the Table of Materials) and dispense at the center of the parylene-coated wafer. Spin coat the wafers at 3000 rpm for 30 s. 
		NOTE: Spin coating must be done under the hood.</li>
		<li>Wait 1 min, bake wafer on a hot plate at 105 &#176;C for 1 min.</li>
		<li>Load photomask in a mask alignment system (see the Table of Materials). Expose wafers to UV light (&#955;=325 nm) for 10 s with a dosage of 65 mJ/cm2.</li>
		<li>Let the wafers sit for another 5 min at room temperature.</li>
		<li>Develop wafers by submerging in developer&#160;(see the Table of Materials) solution for 2 min. Rinse the wafers with deionized water, and then dry with N2. Do this under the hood. 
		NOTE: After developing, photoresist appears completely removed from areas exposed to UV. Use an optical microscope (see the Table of Materials) to verify the wafers.</li>
	</ol>
	</li>
	<li>Reactive ion etching
	<ol>
		<li>Use a reactive ion etching (RIE) tool (see the Table of Materials) to etch developed wafers with oxygen plasma.</li>
		<li>Apply an oxygen flow rate of 50 cm3/min at a chamber pressure of 20 mTorr.</li>
		<li>For a parylene film thickness of 1 &#181;m, use RF power of 50 W and inductively coupled plasma (ICP) power of 500 W for 100 s was to remove exposed parylene from patterned areas. This corresponded to a parylene etch rate of 1.0-1.15 &#181;m/min.</li>
		<li>For a parylene thickness of 80 nm, use RF power of 50 W and ICP power of 200 W for 55 s to remove exposed parylene from patterned areas. This corresponds to a parylene etch rate of 570-620 nm/min. 
		NOTE: For efficient parylene removal, determine the parylene etch rate for each RIE system.</li>
		<li>Inspect etched substrates with an optical microscope. The silicon surface will appear shiny after the parylene is completely removed from exposed regions.</li>
		<li>Verify etch depth using a surface profilometer (see the Table of Materials).</li>
	</ol>
	</li>
</ol>
3. Parylene Lift-off Procedure
<ol>
	<li>Preparation of polymer solutions
	<ol>
		<li>Dissolve PGMA-b-PVDMA into chloroform (1% wt.). Chloroform should be anhydrous to prevent hydrolysis of azlactone groups. 
		NOTE: Chloroform is the preferred solvent because it has a high degree of solubility for the polymer, allowing for more uniform surface deposition of single polymer chains compared to other organic solvents25.</li>
	</ol>
	</li>
	<li>Cleaning parylene stencils with the plasma cleaner
	<ol>
		<li>Turn on the plasma cleaner (see the Table of Materials) main power and put the parylene-coated substrates in the plasma cleaner chamber.</li>
		<li>Turn on the vacuum pump and evacuate the air in the chamber until the pressure gauge is less than 400 mTorr.</li>
		<li>Slightly open the metering valve and allow the air to enter to the plasma cleaner until the pressure gauge shows 800-1000 mTorr.</li>
		<li>Select RF with Hi mode and expose the substrates for 3 min.</li>
		<li>At the end of process, turn off the RF power and vacuum pump.</li>
		<li>Turn off the plasma cleaner and remove the substrates. 
		NOTE: After plasma cleaning, the surface shows hydrophilic behavior (Figure 1B) . The water contact angle of bare silicon surfaces before and after plasma cleaning are 27&#176; &#177; 2&#176; and 0&#176;, respectively.</li>
	</ol>
	</li>
	<li>Spin-coating of PGMA-b-PVDMA, annealing and sonication over the parylene stencils
	<ol>
		<li>Immediately spin-coat the substrates with 100 &#181;L of 1% wt. PGMA-b-PVDMA in anhydrous chloroform at 1500 rpm, for 15 s using a spin coater (see the Table of Materials). 
		NOTE: Perform spin-coating within 1-2 s of pipetting the polymer solution to minimize film non-uniformity caused by rapid chloroform evaporation.</li>
		<li>Anneal the polymer films at 110 &#176;C in a vacuum oven (see the Table of Materials) for 18 h. 
		NOTE: Annealing allows for polymer microphase segregation and surface attachment of the GMA block to the surface26.
		<ol>
			<li>After the annealing, characterize the polymer coating by measuring the contact angle of substrates. Surfaces show a contact angle of 75&#176;&#177; 1&#176; (Figure 1C)20.</li>
		</ol>
		</li>
		<li>Sonicate the substrates in 20 mL of acetone or chloroform for 10 min to remove the parylene layer and any physisorbed polymer. 
		NOTE: Use the following sonication conditions: ultra sonic power, 284 W; Operating frequency, 40 kHz (see the Table of Materials). 
		NOTE: Parylene can also be peeled off the substrate by applying a piece of Scotch tape at the edge of the substrate then pulling the tape away27.</li>
		<li>Store the substrates under vacuum in a desiccator until characterization.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57562/57562fig1.jpg" /> 
Figure 1: Contact angle measurements for treated silicon substrates. (A) Bare silicon, (B) Plasma-cleaned silicon, (C) Spin-coated silicon with PGMA-b-PVDMA (after annealing and sonication in chloroform). <a href="https://www.jove.com/files/ftp_upload/57562/57562fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
4. PGMA-b-PVDMA Interface-Directed Assembly Procedure
NOTE: This procedure can be performed on substrates containing either a chemically inert background (section 4.1), or a biologically inert background (section 4.2), depending on the application.
<ol>
	<li>Preparation of chemically inert background on silicon substrates
	<ol>
		<li>Use oxygen plasma cleaner to clean the bare silicon (section 3.2).</li>
		<li>Pipette 100 &#181;L of trichloro(1H,1H,2H,2H-perfluorooctyl) silane (TPS) onto a Petri dish and place the silicon substrates inside a vacuum desiccator next to the Petri dish.</li>
		<li>Apply vacuum (-750 Torr) for 1 h for chemical vapor deposition (CVD). 
		CAUTION: TPS is highly toxic and the CVD process should be performed inside a fume hood. 
		NOTE: After 1 h the substrate shows hydrophobic behavior. A contact angle of 109&#176;&#177; 3&#176; is typically measured after the CVD process. The thickness of the TPS film is 1.5 &#177; 0.5 nm. 
		NOTE: TPS blocks reaction of the reactive surface oxide with PGMA-b-PVDMA.</li>
		<li>Coat the wafers with parylene (1 &#181;m thickness). Perform photolithography and reactive ion etching to generate parylene patterns (section 2) and to etch away the TPS layer in the exposed regions.</li>
	</ol>
	</li>
	<li>Preparation of polyethylene glycol (PEG) background on silicon substrates.
	<ol>
		<li>Use the oxygen plasma cleaner for 3 min to clean the bare silicon substrates (section 3.2).</li>
		<li>Perform CVD of TPS for 1 h (section&#160;4.1.2).</li>
		<li>Immerse substrates into a 0.7% wt/v solution of Pluronic F-127 in ultrapure water for 18 h to generate a PEG layer on the surface28,29. 
		NOTE: Pluronic contains a hydrophobic polypropylene oxide (PPO) polymer block between&#160;two PEG chains. The PPO block anchors the polymer to the TPS surface while the PEG chains are exposed to solution28.</li>
		<li>Wash and rinse the substrate for 5 min with 100 mL of ultrapure water.</li>
		<li>Deposit 80 nm and 1 &#181;m thick parylene N on 4-inch silicon wafers using a parylene coater.</li>
		<li>Perform photolithography and reactive ion etching to generate parylene patterns (section 2).</li>
	</ol>
	</li>
	<li>Sonication, spin-coating of PGMA-b-PVDMA polymer, and annealing the substrates
	<ol>
		<li>Sonicate chemically inert (TPS) substrates (section 4.1) or PEG-functional substrates (section 4.2) for 10 min in acetone to remove the parylene layer.</li>
		<li>Spin-coat the sonicated substrate with 100 &#181;L of 1% wt. PGMA-b-PVDMA in anhydrous chloroform at 1500 rpm for 15 s.</li>
		<li>Anneal the polymer films at 110 &#176;C under vacuum for 18 h.</li>
		<li>Sonicate the substrates in acetone or chloroform for 10 min to remove physisorbed polymer present in background regions on the surface.</li>
		<li>Store the substrates in a vacuum desiccator until further use.</li>
	</ol>
	</li>
</ol>
5. Custom PGMA-b-PVDMA Micro-Contact Printing (&#956;CP)
<ol>
	<li>PDMS stamp fabrication
	<ol>
		<li>Fabricate the silicon masters according to the standard photolithography procedure30. Use CVD process (section 4.1.2) to deposit anti-adhesive TPS onto the silicon masters. 
		NOTE: The silicon mold should be treated with TPS the first time it is used, and re-applied after it has been used 5-10 times.</li>
		<li>Perform standard soft lithography methods for fabrication of stamps (PDMS precursor to curing agent mass ratio 10:1)31. 
		NOTE: Stamps used in this study consist of micropillar arrays (diameter = 5-50 &#181;m, height = 20 &#181;m).</li>
		<li>Cut out a single stamp. Clean the stamp by sonicating for 10 min in HCl (1 M), 5 min in acetone, followed by 5 min in ethanol.</li>
		<li>Dry the stamps in a convection oven at 80 &#176;C for 20 min to remove residual organic solvent.</li>
	</ol>
	</li>
	<li>Microcontact printing of PGMA-b-PVDMA onto silicon substrates
	<ol>
		<li>Deposit TPS onto the surface of PDMS stamps using the CVD process (section 4.1.2). 
		NOTE: The TPS layer is used to prevent coupling of the polymer to the stamp surface. 
		NOTE: Contact angle measurements can be used to characterize stamps after TPS adsorption, as shown in Figure 2 (Inset A, B).</li>
		<li>Dissolve the PGMA-b-PVDMA polymer into anhydrous chloroform at a concentration of 0.25-1% wt.</li>
		<li>Submerge the stamps into 5 mL of the polymer solution for 3 min.</li>
		<li>Plasma clean 2&#215;2 cm bare silicon substrates for 3 min to clean surface for coupling with the PGMA blocks (section 3.2).</li>
		<li>Take out the polymer-coated stamps from the polymer solution. 
		NOTE: Stamps must be used for printing while they are still wet and a layer of solution exists over them.</li>
		<li>Put inked stamp directly on silicon substrate.</li>
		<li>Use a manual drill press stand (see the Table of Materials) (Figure 3) to press the polymer-coated stamps onto the silicon surface to promote pattern transfer. Immediately apply the stamp to the substrate (within 1-2 s) after taking out the coated stamps from polymer solution. 
		NOTE: Both the silicon and the PDMS stamp can be placed on double-sided tape backing to minimize PDMS stamp deformation due to non-uniform or high pressure stamping32.</li>
		<li>Apply conformal contact between polymer-inked stamp and silicon substrate for 1 min. Use the estimated pressure of 75 g/cm2(7.35 kPa) to press.</li>
		<li>Gently separate the stamp from the silicon surface.</li>
		<li>Anneal the printed silicon substrates immediately in a vacuum oven at 110 &#176;C for 18 h.</li>
		<li>Sonicate the printed silicon substrates in acetone or chloroform for 10 min to remove any physically-adsorbed PGMA-b-PVDMA and then dry with N2.
		<ol>
			<li>Perform surface characterization analysis for both PDMS stamp (after printing step) and printed-silicon (after annealing and sonication steps) to verify the successful transfer of PGMA-b-PVDMA. 
			NOTE: Surface profilometer and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) analysis could be used to analyze the printed-silicon substrate and PDMS stamp, respectively.</li>
		</ol>
		</li>
		<li>Store the substrates under vacuum in a desiccator until characterization.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57562/57562fig2.jpg" /> 
Figure 2: ATR-FTIR measurements for treated PDMS stamps (Relative intensity). (Inset A) Contact angle measurements for bare PDMS stamp. (Inset B) Contact angle measurements for TPS treated PDMS stamp. <a href="https://www.jove.com/files/ftp_upload/57562/57562fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57562/57562fig3.jpg" /> 
Figure 3: Setup for &#956;CP of PGMA-b-PVDMA solutions onto silicon substrates. The procedure includes use of a (A)&#160;manual drill press, (B) a TPS-functionalized PDMS stamp coated with the PGMA-b-PVDMA polymer, (C) a plasma cleaned 2&#215;2 cm silicon substrate, and (D) double-sided tape.

The authors have nothing to disclose.

This article presents three approaches to patterning PGMA-b-PVDMA, each with its set of advantages and drawbacks. The parylene lift-off method is a versatile method for patterning block co-polymers at micro to nanoscale resolution, and has been used as a deposition mask in other patterning systems33,34,35. Due to its relatively weak surface adhesion, the parylene stencil can be easily removed from the surface by sonicat...

Developing fabrication techniques that allow for versatile and precise control of chemical and biological surface functionality is desirable for a variety of applications, from capture of environmental contaminants to development of next generation biosensors, implants, and tissue engineering devices1,2. Functional polymers are excellent materials for tuning surface properties through &#34;grafting from&#34; or &#34;grafting to&#34; techniques3. These approaches allow for control of surface reactivity based on the chemical functionality of the monomer and molecular weight of the polymer4,5,6. Azlactone-based polymers have been intensely studied in this context, as azlactone groups rapidly couple with different nucleophiles in ring-opening reactions. This includes primary amines, alcohols, thiols and hydrazine groups, thereby providing a versatile route for further surface functionalization7,8. Azlactone-based polymer films have been employed in different environmental and biological applications including analyte capture9,10, cell culture6,11, and anti-fouling/anti-adhesive coatings12. In many biological applications, patterning azlactone polymer films at nano to micrometer length scales is desirable to facilitate spatial control of biomolecule presentation, cellular interactions, or to modulate surface interactions13,14,15,16,17,18. Therefore, fabrication methods should be developed to offer high pattern uniformity and well-controlled film thickness, without compromising chemical functionality19.
Recently, Lokitz et al. developed a PGMA-b-PVDMA block copolymer which was capable of manipulating surface reactivity. PGMA blocks couple to oxide-bearing surfaces, yielding high and tunable surface densities of azlactone groups20.&#160;Previously reported methods for patterning this polymer for creation of biofunctional interfaces used traditional top-down photolithography approaches that generated non-uniform polymer films with background regions contaminated with residual photoresist material, causing high levels of non-specific chemical and biological interactions21,22,23. Here, attempts to passivate background regions caused cross-reaction with azlactone groups, compromising polymer reactivity. Considering these limitations, we recently developed techniques for patterning brush (~90 nm) or highly crosslinked (~1-10 &#956;m) films of PGMA-b-PVDMA into chemically or biologically inert backgrounds in a manner that completely preserves the chemical functionality of the polymer24. These presented methods utilize parylene lift-off, interface-directed assembly (IDA), and custom microcontact printing (&#956;CP) techniques. Highly detailed experimental methods for these patterning approaches, as well as critical film characterizations and challenges and limitations associated with each technique are presented here in written and video format.

<table>
	<tbody>
		<tr>
			<td>Material</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol, &#8805; 99.5%</td>
			<td>Sigma-Aldrich</td>
			<td>459844</td>
			<td>-</td>
		</tr>
		<tr>
			<td>HCL, 1.019 N in H2O</td>
			<td>Fluka Analytical</td>
			<td>318949</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Acetone, &#8805; 99.5%</td>
			<td>Sigma-Aldrich</td>
			<td>320110</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Benzene, &#8805; 99.9%</td>
			<td>Sigma-Aldrich</td>
			<td>270709</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Isopropanol, ACS reagent, &#8805;99.5%</td>
			<td>Sigma-Aldrich</td>
			<td>190764</td>
			<td></td>
		</tr>
		<tr>
			<td>Hexane</td>
			<td>Fisher Chemical</td>
			<td>H292-4</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Argon</td>
			<td>Matheson Gas</td>
			<td>G1901175</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Tetrahydrofuran (THF), &#8805; 99.9%</td>
			<td>Sigma-Aldrich</td>
			<td>401757</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Pluronic F-127</td>
			<td>Sigma-Aldrich</td>
			<td>P2443</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Polydimethyl Siloxane (PDMS) Slygard 184</td>
			<td>Dow Corning</td>
			<td>4019862</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Trichloro (1H,1H,2H,2H-perfluorooctyl) silane (TPS), 97%</td>
			<td>Sigma-Aldrich</td>
			<td>448931</td>
			<td>It is toxic. Work with it under hood</td>
		</tr>
		<tr>
			<td>Anhydrous Chloroform, &#8805; 99%</td>
			<td>Sigma-Aldrich</td>
			<td>372978</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Positive Photoresist AZ1512</td>
			<td>MicroChemicals</td>
			<td>AZ 1512</td>
			<td>amber-red liquid, density 1.083 g/cm3, spin coating step should be done under the hood</td>
		</tr>
		<tr>
			<td>Developer AZ 300 MIF</td>
			<td>MicroChemicals</td>
			<td>AZ300 MIF</td>
			<td>clear colourless liquid with slight amine odor and density of 1 g/cm3</td>
		</tr>
		<tr>
			<td>1,2-Vinyl-4,4- dimethyl azlactone (VDMA)</td>
			<td>Isochem North America, LLC</td>
			<td>VDMA</td>
			<td>-</td>
		</tr>
		<tr>
			<td>2-cyano-2-propyl dodecyl trithiocarbonate (CPDT)</td>
			<td>Sigma-Aldrich</td>
			<td>723037</td>
			<td>-</td>
		</tr>
		<tr>
			<td>2,2&#8242;-Azobis (4methoxy-2,4-dimethyl valeronitrile) (V-70)</td>
			<td>Wako Specialty Chemicals</td>
			<td>CAS NO. 15545-97-8, EINECS No. 239-593-8</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Parylene N</td>
			<td>Specialty Coating Systems</td>
			<td>15B10004</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>Parylene Coater</td>
			<td>Specialty Coating Systems</td>
			<td>SCS Labcoater (PDS 2010)</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Mask alignment system</td>
			<td>Neutronix Quintel</td>
			<td>NXQ8000</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Oxygen Plasma Etcher</td>
			<td>Oxford Instruments</td>
			<td>Plasma Lab System 100</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Surface Profilometer</td>
			<td>Veeco</td>
			<td>Dektak 150</td>
			<td>Scan type was standard hill. Scan duration and force were 120 s and 1 mg, respectively.</td>
		</tr>
		<tr>
			<td>Brightfield Upright Microscope</td>
			<td>Olympus Corporation</td>
			<td>BX51</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Oxygen Plasma&#160; Cleaner</td>
			<td>Harrick Plasma</td>
			<td>PDC-001-HP</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR)</td>
			<td>Perkin Elmer</td>
			<td>ATR-FTIR 100</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Atomic Force Microscopy (AFM)</td>
			<td>PicoPlus</td>
			<td>Picoplus atomic force microscope</td>
			<td>Veeco MLCT-E cantilevers with a 0.5 N/m spring constant. Scan speeds varied between 0.25 and 1 Hz.</td>
		</tr>
		<tr>
			<td>Scanning Electron Microscopy (SEM)</td>
			<td>Hitachi Science Systems Ltd., Tokyo, Japan</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Rotary Tool Workstation</td>
			<td>Dremel</td>
			<td>Model 220-01</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Spin Coater</td>
			<td>Smart Coater</td>
			<td>SC100</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Vacuum Oven</td>
			<td>Yamato Scientific Co.</td>
			<td>PCD-C6(5)000)</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Size Exclusion Chromatography (SEC)</td>
			<td>Waters Alliance 2695 Separations Module</td>
			<td>720004547EN</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Refractive Index (RI) detector</td>
			<td>Waters</td>
			<td>Model 2414</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Photodiode Array Detector</td>
			<td>Waters</td>
			<td>Model 2996, 716001286</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Multi-angle Light Scattering (MALS) Detector</td>
			<td>Wyatt Technology</td>
			<td>miniDAWN TREOS II</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Viscometer</td>
			<td>Wyatt Technology</td>
			<td>Viscostar</td>
			<td>-</td>
		</tr>
		<tr>
			<td>PLgel 5 &#181;m mixed-C columns (300 x 7.5 mm)</td>
			<td>Agilent</td>
			<td>5 &#181;m mixed-C columns</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Ellipsometer</td>
			<td>J. A. Woollam</td>
			<td>alpha-SE</td>
			<td>Cauchy model, PGMA and PVDMA layers had refractive indices of 1.50 and 1.52 at 632 nm</td>
		</tr>
		<tr>
			<td>Ultrasonic Sonicator</td>
			<td>Fischer Scientific</td>
			<td>FS-110H</td>
			<td>-</td>
		</tr>
	</tbody>
</table>

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.

Contact angle measurements can be used to evaluate the functionalization of silicon with PGMA-b-PVDMA. Figure 1 depicts the contact angle of the silicon substrate during the different processing steps. Hydrophilic behavior of the plasma cleaned silicon substrate is shown in Figure 1B. The contact angle after polymer spin coating and annealing is 75&#176; &#177; 1&#176;(Figure 1C)...

Watch this Scientific Journal Video about Fabricating Reactive Surfaces with Brush-like and Crosslinked Films of Azlactone-Functionalized Block Co-Polymers at JoVE.com

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

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 ...

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8.2K Views.  Kansas State University. 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.

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

Fabricating Metamaterials Using the Fiber Drawing Method

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe their electromagnetic properties to the structure of their constituents, instead of the atoms that compose them. For example, sub-wavelength metal wires can be arranged to possess an effective electric permittivity that is either positive or negative at a given frequency, in contrast to the metals themselves 2. This unprecedented control over the behaviour of light can potentially lead to a number of novel devices, such as invisibility cloaks 3, negative refractive index materials 4, and lenses that resolve objects below the diffraction limit 5. However, metamaterials operating at optical, mid-infrared and terahertz frequencies are conventionally made using nano- and micro-fabrication techniques that are expensive and produce samples that are at most a few centimetres in size 6-7. Here we present a fabrication method to produce hundreds of meters of metal wire metamaterials in fiber form, which exhibit a terahertz plasmonic response 8. We combine the stack-and-draw technique used to produce microstructured polymer optical fiber 9 with the Taylor-wire process 10, using indium wires inside polymethylmethacrylate (PMMA) tubes. PMMA is chosen because it is an easy to handle, drawable dielectric with suitable optical properties in the terahertz region; indium because it has a melting temperature of 156.6 &deg;C which is appropriate for codrawing with PMMA. We include an indium wire of 1 mm diameter and 99.99% purity in a PMMA tube with 1 mm inner diameter (ID) and 12 mm outside diameter (OD) which is sealed at one end. The tube is evacuated and drawn down to an outer diameter of 1.2 mm. The resulting fiber is then cut into smaller pieces, and stacked into a larger PMMA tube. This stack is sealed at one end and fed into a furnace while being rapidly drawn, reducing the diameter of the structure by a factor of 10, and increasing the length by a factor of 100. Such fibers possess features on the micro- and nano- scale, are inherently flexible, mass-producible, and can be woven to exhibit electromagnetic properties that are not found in nature. They represent a promising platform for a number of novel devices from terahertz to optical frequencies, such as invisible fibers, woven negative refractive index cloths, and super-resolving lenses.

Metamaterials at terahertz frequencies offer unique opportunities, but are challenging to fabricate in bulk. We adapt the fabrication procedure for microstructured polymer optical fibers to inexpensively fabricate metamaterials potentially on an industrial scale. We produce polymethylmethacrylate fibers containing ~10 &mu;m diameter indium wires separated by ~100 &mu;m, which exhibit a terahertz plasmonic response.

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe ...

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM, other properties such as local electronic states, ion diffusion coefficient and surface potential can also be investigated17-22. In this work, electrochemical measurements, Raman spectroscopy, and SPM were used in conjunction with a novel test electrode platform that consists of a Ni mesh electrode embedded in an yttria-stabilized zirconia (YSZ) electrolyte. Cell performance testing and impedance spectroscopy under fuel containing H2S was characterized, and Raman mapping was used to further elucidate the nature of sulfur poisoning. In situ Raman monitoring was used to investigate coking behavior. Finally, atomic force microscopy (AFM) and electrostatic force microscopy (EFM) were used to further visualize carbon deposition on the nanoscale. From this research, we desire to produce a more complete picture of the SOFC anode.

We present a unique platform for characterizing electrode surfaces in solid oxide fuel cells (SOFCs) that allows simultaneous performance of multiple characterization techniques (e.g. in situ Raman spectroscopy and scanning probe microscopy alongside electrochemical measurements). Complementary information from these analyses may help to advance toward a more profound understanding of electrode reaction and degradation mechanisms, providing insights into rational design of better materials for SOFCs.

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen ...

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

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

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

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

Monolayer Contact Doping of Silicon Surfaces and Nanowires Using Organophosphorus Compounds

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra shallow and sharp doping profiles at the nanometer scale. In MLCD process the dopant source is a monolayer containing dopant atoms.
In this article a detailed procedure for surface doping of silicon substrate as well as silicon nanowires is demonstrated. Phosphorus dopant source was formed using tetraethyl methylenediphosphonate monolayer on a silicon substrate. This monolayer containing substrate was brought to contact with a pristine intrinsic silicon target substrate and annealed while in contact. Sheet resistance of the target substrate was measured using 4 point probe. Intrinsic silicon nanowires were synthesized by chemical vapor deposition (CVD) process using a vapor-liquid-solid (VLS) mechanism; gold nanoparticles were used as catalyst for nanowire growth. The nanowires were suspended in ethanol by mild sonication. This suspension was used to dropcast the nanowires on silicon substrate with a silicon nitride dielectric top layer. These nanowires were doped with phosphorus in similar manner as used for the intrinsic silicon wafer. Standard photolithography process was used to fabricate metal electrodes for the formation of nanowire based field effect transistor (NW-FET). The electrical properties of a representative nanowire device were measured by a semiconductor device analyzer and a probe station.

A detailed procedure for surface doping of Silicon interfaces is provided. The ultra-shallow surface doping is demonstrated by using phosphorus containing monolayers and rapid annealing process. The method can be used for doping of macroscopic area surfaces as well as nanostructures.

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra ...

Speciation and Bioavailability Measurements of Environmental Plutonium Using Diffusion in Thin Films

The biological uptake of plutonium (Pu) in aquatic ecosystems is of particular concern since it is an alpha-particle emitter with long half-life which can potentially contribute to the exposure of biota and humans. The diffusive gradients in thin films technique is introduced here for in-situ measurements of Pu bioavailability and speciation. A diffusion cell constructed for laboratory experiments with Pu and the newly developed protocol make it possible to simulate the environmental behavior of Pu in model solutions of various chemical compositions. Adjustment of the oxidation states to Pu(IV) and Pu(V) described in this protocol is essential in order to investigate the complex redox chemistry of plutonium in the environment. The calibration of this technique and the results obtained in the laboratory experiments enable to develop a specific DGT device for in-situ Pu measurements in freshwaters. Accelerator-based mass-spectrometry measurements of Pu accumulated by DGTs in a karst spring allowed determining the bioavailability of Pu in a mineral freshwater environment. Application of this protocol for Pu measurements using DGT devices has a large potential to improve our understanding of the speciation and the biological transfer of Pu in aquatic ecosystems.

The technique of diffusive gradients in thin films (DGT) is proposed for speciation studies of plutonium. This protocol describes diffusion experiments probing the behavior of Pu(IV) and Pu(V) in presence of organic matter. DGTs deployed in a karstic spring allow assessment of the bioavailability of Pu.

The biological uptake of plutonium (Pu) in aquatic ecosystems is of particular concern since it is an alpha-particle emitter with long half-life which can ...

Electrospray Deposition of Uniform Thickness Ge23Sb7S70 and As40S60 Chalcogenide Glass Films

Solution-based electrospray film deposition, which is compatible with continuous, roll-to-roll processing, is applied to chalcogenide glasses. Two chalcogenide compositions are demonstrated: Ge23Sb7S70 and As40S60, which have both been studied extensively for planar mid-infrared (mid-IR) microphotonic devices. In this approach, uniform thickness films are fabricated through the use of computer numerical controlled (CNC) motion. Chalcogenide glass (ChG) is written over the substrate by a single nozzle along a serpentine path. Films were subjected to a series of heat treatments between 100 &#176;C and 200 &#176;C under vacuum to drive off residual solvent and densify the films. Based on transmission Fourier transform infrared (FTIR) spectroscopy and surface roughness measurements, both compositions were found to be suitable for the fabrication of planar devices operating in the mid-IR region. Residual solvent removal was found to be much quicker for the As40S60 film as compared to Ge23Sb7S70. Based on the advantages of electrospray, direct printing of a gradient refractive index (GRIN) mid-IR transparent coating is envisioned, given the difference in refractive index of the two compositions in this study.

Electrospray Deposition of Uniform Thickness Ge23Sb7S70 and As40S60 Chalcogenide Glass Films

A method of uniform thickness solution-derived chalcogenide glass film deposition is demonstrated using computer numerical controlled motion of a single-nozzle electrospray.

Solution-based electrospray film deposition, which is compatible with continuous, roll-to-roll processing, is applied to chalcogenide glasses. Two ...

Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns

In this study, pool-boiling heat-transfer experiments were performed to investigate the effect of the number of interlines and the orientation of the hybrid wettable pattern. Hybrid wettable patterns were produced by coating superhydrophilic SiO2 on a masked, hydrophobic, cylindrical copper surface. Using de-ionized (DI) water as the working fluid, pool-boiling heat-transfer studies were conducted on the different surface-treated copper cylinders of a 25-mm diameter and a 40-mm length. The experimental results showed that the number of interlines and the orientation of the hybrid wettable pattern influenced the wall superheat and the HTC. By increasing the number of interlines, the HTC was enhanced when compared to the plain surface. Images obtained from the charge-coupled device (CCD) camera indicated that more bubbles formed on the interlines as compared to other parts. The hybrid wettable pattern with the lowermost section being hydrophobic gave the best heat-transfer coefficient (HTC). The experimental results indicated that the bubble dynamics of the surface is an important factor that determines the nucleate boiling.

Pool-boiling heat-transfer experiments were carried out to observe the effects of hybrid wettable patterns on the heat-transfer coefficient (HTC). The parameters of investigation are the number of interlines and the pattern orientation of the modified wettable surface.

In this study, pool-boiling heat-transfer experiments were performed to investigate the effect of the number of interlines and the orientation of the ...

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 ...

Fabrication of Superhydrophobic Metal Surfaces for Anti-Icing Applications

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

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

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

Scalable Stamp Printing and Fabrication of Hemiwicking Surfaces

Hemiwicking is a process where a fluid wets a patterned surface beyond its normal wetting length due to a combination of capillary action and imbibition. This wetting phenomenon is important in many technical fields ranging from physiology to aerospace engineering. Currently, several different techniques exist for fabricating hemiwicking structures. These conventional methods, however, are often time consuming and are difficult to scale-up for large areas or are difficult to customize for specific, nonhomogeneous patterning geometries. The presented protocol provides researchers with a simple, scalable, and cost-effective method for fabricating micro-patterned hemiwicking surfaces. The method fabricates wicking structures through the use of stamp printing, polydimethylsiloxane (PDMS) molding, and thin-film surface coatings. The protocol is demonstrated for hemiwicking with ethanol on PDMS micropillar arrays coated with a 70 nm thick aluminum thin-film.

A simple protocol is provided for the fabrication of hemiwicking structures of varying sizes, shapes, and materials. The protocol uses a combination of physical stamping, PDMS molding, and thin-film surface modifications via common materials deposition techniques.

Hemiwicking is a process where a fluid wets a patterned surface beyond its normal wetting length due to a combination of capillary action and imbibition. ...