Name: the evolution of silica nanoparticle-polyester coatings on surfaces exposed to sunlight
Uploaded: 2016-10-11T14:00:00.000+00:00
Duration: 10 min 27 s
Description: Watch this Scientific Journal Video about The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight at JoVE.com

Funding from the Australian Research Council Industrial Transformation Research Hubs Scheme (Project Number IH130100017) is gratefully acknowledged. Authors gratefully acknowledge the RMIT Microscopy and Microanalysis Facility (RMMF) for providing access to the characterisation instruments. This research was also undertaken on the Infrared Microscopectroscopy beamline at the Australian Synchrotron, Victoria, Australia.

1. Steel Samples
<ol>
	<li>Obtain steel samples of 1 mm thickness from a commercial supplier. 
	NOTE: Samples were coated with either polyester or polyester coated with silica nanoparticles.</li>
	<li>Expose samples to sunlight at Rockhampton, Queensland, Australia: collect samples after one-year and five-year intervals over a total 5-year period. Cut sample panels into round discs of 1 cm diameter using hole puncher.</li>
	<li>Prior to surface characterization, rinse samples with double-distilled water, and then dry using nitrogen gas (99.99%). Keep all samples in air-tight containers to prevent any air contaminants adsorbing to the surface (Figure 1).</li>
</ol>
<img alt="Figure 1" src="/files/ftp_upload/54309/54309fig1.jpg" /> 
Figure 1. Preparation of metal discs with polyester-based coating. Samples were stored in containers until required. <a href="http://cloudfront.jove.com/files/ftp_upload/54309/54309fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
2. Chemical and Physicochemical Characterization of Surfaces
<ol>
	<li>Analyze surface chemistry using X-ray photoelectron spectroscopy.
	<ol>
		<li>Perform X-ray photoelectron spectrometry (XPS) using a monochromatic X-ray source (Al K&#945;, h&#957; = 1486.6 eV) operating at 150 W. 
		NOTE: Spot size of utilized X-ray beam is 400 &#181;m in diameter.</li>
		<li>Load samples on the sample plate. Place the sample plate into vacuum chamber of XPS then pump the chamber. Wait for the vacuum in the chamber to reach ~1 &#215; 10-9 mbar.</li>
		<li>In the photoelectron spectroscopy software, press the option of &#34;Flood Gun&#34; to flood the samples with low-energy electrons to counteract surface charging.</li>
		<li>Press &#34;Insert&#34;&#62;&#34;Point&#34;&#62;&#34;Point&#34; to insert an analysis point. 
		NOTE: This will be a location at which analysis is performed. Enable the auto height function to obtain the best height for acquisition.</li>
		<li>Press &#34;Insert&#34;&#62;&#34;Spectrum&#34;&#62;&#34;Multi Spectrum&#34; to add scans to this point. 
		NOTE: This will open a window with a periodic table; select an element by clicking on it to highlight it.</li>
		<li>After setting up the experiments, press the &#34;Play&#34; command to proceed the scans.</li>
		<li>Press &#34;Peak Fit&#34; command then press &#34;Add Peak&#34; and &#34;Fit All Level&#34; commands to resolve the chemically distinct species in the high-resolution spectra. 
		NOTE: This step will acquire the Shirley algorithm to remove the background and Gaussian-Lorentzian fitting to deconvolute the spectra19.</li>
		<li>Select all high-resolution and survey spectra. Press &#34;Charge Shift&#34; option to correct spectra using the hydrocarbon component of the C 1s peak (binding energy 285.0 eV) as a reference.</li>
		<li>After charge correction, press &#34;Export&#34; option to generate the data table of the relative atomic concentration of elements on the basis of the peak area.</li>
	</ol>
	</li>
	<li>Surface chemistry 
	NOTE: Analyze surface chemistry using attenuated total reflection infrared micro-spectroscopy (ATR-IR) on the infrared (IR) spectroscopy beamline at the Australian Synchrotron as following:
	<ol>
		<li>Load samples on the stage of microscope. Open a &#34;Start Video Assisted Measurement&#34; or &#34;Start Measurement without 3D&#34; option. Turn &#34;VIS&#34; mode on. Use the objective to focus on sample surface. Press &#34;Snapshot/Overview&#34; to take desired images. 
		NOTE: 0.5 mm thick CaF2plate can be used as the background.</li>
		<li>Change the ATR objective to the sample. Carefully move the stage to place a 45&#176; multi-reflection germanium crystal (refractive index of 4) 1-2 mm above surfaces. Right-click on the Live Video window. Press &#34;Start Measurement&#34;&#62;&#34;Change Measurement Parameters&#34;. Choose the option &#34;Never use existing BG for all positions&#34;. 
		NOTE: This will choose not to take background spectra for every measurement point.</li>
		<li>Draw a map on video screen to choose the area of interest. Press a red aperture square and choose &#34;Aperture&#34;&#62;&#34;Change Aperture&#34;. Change the actual &#34;Knife Edge Aperture&#34; settings to X = 20 &#181;m and Y = 20 &#181;m.</li>
		<li>Right-click on the newly sized aperture square and go to &#34;Aperture&#34;&#62; &#34;Set all Apertures to selected Apertures&#34;. Press &#34;Measurement&#34; icon to start the scans. Save the data. 
		NOTE: The refractive index of Ge crystal is 4, so an aperture of 20 &#181;m &#215; 20 &#181;m will define the spot size of 5 &#181;m &#215; 5 &#181;m. This step will allow setting up FTIR mapping with an aperture of 20 by 20 &#181;m, which corresponds to a 5 &#181;m by 5 &#181;m spot through the crystal across a maximum wavenumber range of 4,000-850 cm-1.</li>
		<li>Open master file using spectroscopy software. Choose the peak of interest on IR spectra. Right-click on the peak of interest. Choose &#34;Integration&#34;&#62;&#34;Integration&#34;. It will allow creating 2D false color maps</li>
	</ol>
	</li>
	<li>Surface wettability measurements 
	NOTE: Perform wettability measurement using a contact angle goniometer equipped with a nanodispenser19.
	<ol>
		<li>Place the sample on the stage. Adjust the position of the microsyringe assembly so that the bottom of the needle appears about a fourth of a way down in the Live video window screen.</li>
		<li>Raise the sample using z-axis until distance between the sample and surface is about 5 mm. Move the syringe down until a droplet of double distilled water touches the surface. Move the syringe up to its original position.</li>
		<li>Press the &#34;Run&#34; command to record the water droplet impacting on the surface for a 20 sec period using a monochrome CCD Camera which is integrated with hardware.</li>
		<li>Press the &#34;Stop&#34; command to acquire the series of images.</li>
		<li>Press &#34;Contact Angle&#34; command to measure contact angles from acquired images. Repeat the contact angle measurements at three random locations for each sample.</li>
	</ol>
	</li>
</ol>
3. Visualization of the Surface Topography
<ol>
	<li>Optical profiling measurement. 
	NOTE: The instrument is operated under the white light vertical scanning interferometry mode.
	<ol>
		<li>Place samples on the stage of the microscope. 
		NOTE: Ensure there is a sufficient gap (e.g., &#62;15 mm) between objective lens and the stage.</li>
		<li>Focus on surface using the 5&#215; objectives by controlling z-axis until the fringes appear on the screen. Press &#34;Auto&#34; command to optimize the intensity. Press &#34;Measurement&#34; command to initiate the scanning. Save the master files.</li>
		<li>Repeat the step 3.1.2 for 20&#215; and 50&#215; objectives.</li>
		<li>Prior to statistical roughness analyses, press &#34;Remove Tilt&#34; option to remove the surface waviness. Press &#34;Contour&#34; option to analyze the roughness parameters. Click on &#34;3Di&#34; option to generate three-dimensional images of optical profiling files using compatible software20.</li>
	</ol>
	</li>
	<li>Atomic force microscopy
	<ol>
		<li>Place samples on steel discs. Insert the steel discs into magnetic holder.</li>
		<li>Perform AFM scans in tapping mode21. Mechanically load phosphorus doped silicon probes with a spring constant of 0.9 N/m, tip curvature with radius of 8 nm and a resonance frequency of &#8764;20 kHz for surface imaging.</li>
		<li>Manually adjust the laser reflection on the cantilever. Choose &#34;Auto Tune&#34; command then press &#34;Tune&#34; command to tune the AFM cantilever to reach the optimum resonance frequency reported by the manufacturer.</li>
		<li>Focus on the surface. Move the tips close to sample surface. Click on Engage command to engage AFM tips on surfaces.</li>
		<li>Type &#34;1 Hz&#34; into scanning speed box. Choose the scanning areas. Press &#34;Run&#34; command to perform scan. Repeat the scanning at least for ten areas of each of five samples of each condition.</li>
		<li>Choose the leveling option to process the resulting topographical data. Save the master files.</li>
		<li>Open the compatible AFM software. Load the AFM master file. Press &#34;Leveling&#34; command to remove the tilting of surfaces. Press &#34;Smoothen&#34; command to remove the background.</li>
		<li>Press &#34;Statistical Parameters Analysis&#34; to generate the statistical roughness 21.</li>
	</ol>
	</li>
</ol>
4. Statistical Analysis
<ol>
	<li>Express the results in terms of mean value and its standard deviation. Perform statistical data processing using paired Student&#39;s two-tailed t-tests to evaluate the consistency of results. Set p-value at &#60;0.05 indicating level of statistical significance.</li>
</ol>

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The authors have nothing to disclose.

Polyester coatings have been widely used to protect steel substrata from the corrosion that would occur on an uncoated surface due to the accumulation of moisture and pollutants. The application of polyester coatings can protect the steel from corrosion; however the longer-term effectiveness of these coatings is compromised if they are exposed to high levels of ultraviolet light under humid conditions, as occurs in tropical climates. Silica nanoparticles can be applied to the surface of the polyester to improve the robus...

Environmental corrosion of metals in the environment is both prevalent and costly1-3. A recent study conducted by the Australasian Corrosion Association (ACA) reported that corrosion of metals resulted in a yearly cost of $982 million, which was directly associated with the degradation of assets and infrastructure through metallic corrosion within the water industry4. From an international perspective, the World Corrosion Organization estimated that metallic corrosion was responsible for a direct cost of $3.3 trillion, over 3% of the world's GDP5. The process of galvanizing as a corrosion preventative method has been widely used to increase the lifespan of steel material6. In humid and subtropical climates, however, water tends to condense into small pockets or grooves within the surface of the galvanized steel, leading to the acceleration of corrosion rates through pit corrosion7,8. Thermosetting polymer coatings based on polyesters have been developed to coat the galvanized steel substrata increasing their ability to withstand humid weathering conditions for items such as satellite dishes, garden furniture, air-conditioning units or agricultural construction equipment9-11. Unfortunately polymer coatings on steel surfaces have been found to be considerably adversely affected by the presence of high levels of ultraviolet (uv) radiation12-14. Coatings comprised of silica nanoparticles (SiO2) spread over a polymer layer have been widely used with a view to increasing their corrosion-, wear-, tear- and degradation-resistance15,16. The tendency of the protective polymeric coatings to form pores and cracks can be reduced by incorporating nanoparticles (NPs), which contribute to the passive obstruction of corrosion initiation17,18. Also, the mechanical stability of the protective polymeric layer can be improved by NPs inclusion. However, these coatings act as passive physical barriers and, in comparison to the galvanization approach, cannot inhibit corrosion propagation actively.
An in-depth understanding of the effect that high-levels of ultraviolet light exposure under humid conditions upon these metal coatings is yet to be obtained. In this paper, a wide range of surface analytical techniques, including X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared micro-spectroscopy (ATR IR), contact angle goniometry, optical profiling and atomic force microscopy (AFM) will be employed to examine the changes in the surface of steel coatings prepared from polyester- and silica nanoparticle-coated polyester (silica nanoparticles/polyester) after exposure to sunlight. Furthermore, the aim of this work is to give a concise, practical overview of the overall characterization techniques to examine weathered samples.

<table><tbody><tr><td>polyester-coated steel&lt;br/&gt; silica nanoparticle-polyester coated steel substrata</td><td>BlueScope Steel</td><td></td><td>Samples provided by company</td></tr><tr><td>Millipore PetriSlide&lt;sup&gt;TM&lt;/sup&gt;&amp;nbsp;</td><td>Fisher Scientific</td><td>PDMA04700</td><td>Storing samples</td></tr><tr><td>Thermo Scientific&lt;sup&gt;TM&lt;/sup&gt; K-alpha&lt;br/&gt; X-ray Photoelectron Spectrometer</td><td>Thermo Fisher Scientific, Inc.</td><td>IQLAADGAAFFACVMAHV</td><td>Acquire XPS spectra</td></tr><tr><td>Avantage Data System</td><td>Thermo Fisher Scientific, Inc.</td><td>IQLAADGACKFAKRMAVI</td><td>Analyse XPS spectra</td></tr><tr><td>A Bruker Hyperion 2000 microscope&amp;nbsp;</td><td>Bruker Corporation</td><td></td><td>Synchrotron integrated instrument</td></tr><tr><td>Bruker Opus v. 7.2</td><td>Bruker Corporation</td><td></td><td>ATR-IR analysis software</td></tr><tr><td>Contact angle goniometer, FTA1000c</td><td>First Ten &amp;Aring;ngstroms Inc., VA, USA</td><td></td><td>Measuring the wettability of surfaces</td></tr><tr><td>FTA v. 2.0</td><td>First Ten &amp;Aring;ngstroms Inc., VA, USA</td><td></td><td>Anaylyzing water contact angle</td></tr><tr><td>Optical profiler, Wyko NT1100&amp;nbsp;</td><td>Bruker Corporation</td><td></td><td>Measure surface topography</td></tr><tr><td>Innova atomic force microscope&amp;nbsp;</td><td>Bruker Corporation</td><td></td><td>Measure surface topography</td></tr><tr><td>Phosphorus doped silicon probes, MPP-31120-10</td><td>Bruker Corporation</td><td></td><td>AFM probes</td></tr><tr><td>Gwyddion software</td><td>http://gwyddion.net/</td><td></td><td>Software used to measure optical profiling and AFM data</td></tr></tbody></table>

the evolution of silica nanoparticle-polyester coatings on surfaces exposed to sunlight

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, building and food industries, amongst others. Polyester and coatings containing both polyester and silica nanoparticles (SiO2NPs) have been widely used to protect steel substrata from corrosion. In this study, we utilized X-ray photoelectron spectroscopy, attenuated total reflection infrared micro-spectroscopy, water contact angle measurements, optical profiling and atomic force microscopy to provide an insight into how exposure to sunlight can cause changes in the micro- and nanoscale integrity of the coatings. No significant change in surface micro-topography was detected using optical profilometry, however, statistically significant nanoscale changes to the surface were detected using atomic force microscopy. Analysis of the X-ray photoelectron spectroscopy and attenuated total reflection infrared micro-spectroscopy data revealed that degradation of the ester groups had occurred through exposure to ultraviolet light to form COO&#903;, -H2C&#903;, -O&#903;, -CO&#903; radicals. During the degradation process, CO and CO2 were also produced.

The coated steel samples that had been subjected to exposure to the sunlight for either one or five years were collected, and water contact angle measurements were carried out to determine whether the exposure had resulted in a change in the surface hydrophobicity of the surface (Figure 2).
<img alt="Figure 2" src="/files/ftp_upload/54309/54309fig2.jpg" /> 
Figure 2. Wettability variation of surfaces with polyester or silica nanopa...

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The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight

Two types of surfaces, polyester-coated steel and polyester coated with a layer of silica nanoparticles, were studied. Both surfaces were exposed to sunlight, which was found to cause substantial changes in the chemistry and nanoscale topography of the surface.

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, ...

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Research

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Engineering

9.5K Views.  Swinburne University of Technology. Two types of surfaces, polyester-coated steel and polyester coated with a layer of silica nanoparticles, were studied. Both surfaces were exposed to sunlight, which was found to cause substantial changes in the chemistry and nanoscale topography of the surface.

Video: The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight

Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan &#948; solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials&#39; morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by St&#246;ber&#39;s methods, which have smooth surfaces.

Silica nanoparticles were prepared using acid-catalysis of a siloxane precursor and microwave-assisted synthetic techniques resulting in the controlled growth of nanomaterials ranging from 30-250 nm in diameter. The growth dynamics can be controlled by varying the initial silicic acid concentration, time of the reaction, and temperature of reaction.

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle ...

Chemistry

Stabilizing Hepatocellular Phenotype Using Optimized Synthetic Surfaces

Currently, one of the major limitations in cell biology is maintaining differentiated cell phenotype. Biological matrices are commonly used for culturing and maintaining primary and pluripotent stem cell derived hepatocytes. While biological matrices are useful, they permit short term culture of hepatocytes, limiting their widespread application. We have attempted to overcome the limitations using a synthetic polymer coating. Polymers represent one of the broadest classes of biomaterials and possess a wide range of mechanical, physical and chemical properties, which can be fine-tuned for purpose. Importantly, such materials can be scaled to quality assured standards and display batch-to-batch consistency. This is essential if cells are to be expanded for high through-put screening in the pharmaceutical testing industry or for cellular based therapy. Polyurethanes (PUs) are one group of materials that have shown promise in cell culture. Our recent progress in optimizing a polyurethane coated surface, for long-term culture of human hepatocytes displaying stable phenotype, is presented and discussed.

This article will focus on developing polymer coated surfaces for long-term, stable culture of stem cell derived human hepatocytes.

Currently, one of the major limitations in cell biology is maintaining differentiated cell phenotype. Biological matrices are commonly used for culturing ...

Experimental Protocol to Investigate Particle Aerosolization of a Product Under Abrasion and Under Environmental Weathering

The present article presents an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental weathering, which is a fundamental element to the approach of nanosafety-by-design of nanostructured products for their durable development. This approach is basically a preemptive one in which the focus is put on minimizing the emission of engineered nanomaterials' aerosols during the usage phase of the product's life cycle. This can be attained by altering its material properties during its design phase without compromising with any of its added benefits. In this article, an experimental protocol is presented to investigate the nanosafety-by-design of three commercial nanostructured products with respect to their mechanical solicitation and environmental weathering. The means chosen for applying the mechanical solicitation is an abrasion process and for the environmental weathering, it is an accelerated UV exposure in the presence of humidity and heat. The eventual emission of engineered nanomaterials is studied in terms of their number concentration, size distribution, morphology and chemical composition. The purpose of the protocol is to study the emission for test samples and experimental conditions which are corresponding to real life situations. It was found that the application of the mechanical stresses alone emits the engineered nanomaterials' aerosols in which the engineered nanomaterial is always embedded inside the product matrix, thus, a representative product element. In such a case, the emitted aerosols comprise of both nanoparticles as well as microparticles. But if the mechanical stresses are coupled with the environmental weathering, the experimental protocol reveals then the eventual deterioration of the product, after a certain weathering duration, may lead to the emission of the free engineered nanomaterial aerosols too.

In this article, an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental weathering is presented. Results on the emission of engineered nanomaterials, in the form of aerosols are presented. The specific experimental set-up is described in detail.

The present article presents an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental ...

A Protocol for the Production of Gliadin-cyanoacrylate Nanoparticles for Hydrophilic Coating

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic by a simple spray coating. These nanoparticles are produced by the polymerization reaction of alkyl cyanoacrylate on the surface of cereal protein (gliadin) molecules. Alkyl cyanoacrylate is a monomer that instantly polymerizes at RT when it is applied to the surface of materials. Its polymerization reaction is initiated by the trace amounts of weakly basic or nucleophilic species on the surface, including moisture. Once polymerized, the polymerized alkyl cyanoacrylates show a strong affinity with the object materials because nitrile groups are in the backbone of poly (alkyl cyanoacrylate). Proteins also work as initiator for this polymerization because they contain amine groups that can initiate the polymerization of cyanoacrylate. If aggregated protein is used as an initiator, protein aggregate is surrounded by the hydrophobic poly(alkyl cyanoacrylate) chains after the polymerization reaction of alkyl cyanoacrylate. By controlling the experimental condition, particles in the nanometer range are produced. The produced nanoparticles readily adsorb to the surface of most materials including glass, metals, plastics, wood, leather, and fabrics. When the surface of a material is sprayed with the produced nanoparticle suspension and rinsed with water, the micellar structure of nanoparticle changes its conformation, and the hydrophilic proteins are exposed to the air. As a result, the nanoparticle-coated surface changes to hydrophilic.

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic. The produced nanoparticle is an assembly of gliadin-cyanoacrylate diblock copolymers. Spray coating with the produced nanoparticle changes the surface of target material to a hydrophilic surface.

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic by a simple spray ...

Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise composition of these materials is essential, especially in the design of surface catalysts, where the surface concentration of the active component determines the activity of the material. Antimicrobial materials which utilize nanoparticles are a particular focus of this technology. Recently swell encapsulation has emerged as a technique for inserting antimicrobial nanoparticles into a host polymer matrix. Swell encapsulation provides the advantage of localizing the incorporation to the external surfaces of materials, which act as the active sites of these materials. However, quantification of this nanoparticle uptake is challenging. Previous studies explore the link between antimicrobial activity and surface concentration of the active component, but this is not directly visualized. Here we show a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of CdSe/ZnS nanoparticles can be accurately visualized through cross-sectional fluorescence imaging. Using this method, we can quantify the uptake of nanoparticles via swell encapsulation and measure the surface concentration of encapsulated particles, which is key in optimizing the activity of functional materials.

Here we present a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of cadmium selenide quantum dots can be accurately visualized through cross-sectional fluorescence imaging.

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise ...

TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

This manuscript proposes a soft-chemistry method to develop superhydrophobic and highly IR-reflective hollow glass microspheres (HGM). The anatase TiO2 and a superhydrophobic agent were coated on the HGM surface in one step. TBT and PFOTES were selected as the Ti source and the superhydrophobic agent, respectively. They were both coated on the HGM, and after the hydrothermal process, the TBT turned to anatase TiO2. In this way, a PFOTES/TiO2-coated HGM (MCHGM) was prepared. For comparison, PFOTES single-coated HGM (F-SCHGM) and TiO2 single-coated HGM (Ti-SCHGM) were synthesized as well. The PFOTES and TiO2 coatings on the HGM surface were demonstrated through X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive detector (EDS) characterizations. The MCHGM showed a higher contact angle (153&#176;) but a lower sliding angle (16&#176;) than F-SCHGM, with a contact angle of 141.2&#176; and a sliding angle of 67&#176;. In addition, both Ti-SCHGM and MCHGM displayed similar IR reflectivity values, which were about 5.8% higher than the original HGM and F-SCHGM. Also, the PFOTES coating barely changed the thermal conductivity. Therefore, F-SCHGM, with a thermal conductivity of 0.0479 W/(m&#183;K), was quite like the original HGM, which was 0.0475 W/(m&#183;K). MCHGM and Ti-SCHGM were also similar. Their thermal conductivity values were 0.0543 W/(m&#183;K) and 0.0543 W/(m&#183;K), respectively. The TiO2 coating slightly increased the thermal conductivity, but with the increase in reflectivity, the overall heat-insulation property was enhanced. Finally, since the IR-reflecting property is provided by the HGM coating, if the coating is fouled, the reflectivity decreases. Therefore, with the superhydrophobic coating, the surface is protected from fouling, and its lifetime is also prolonged.

TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

This manuscript proposes a soft-chemistry method to synthesize superhydrophobic, TiO2-coated hollow glass microspheres (HGM) with high IR-reflective properties.

This manuscript proposes a soft-chemistry method to develop superhydrophobic and highly IR-reflective hollow glass microspheres (HGM). The anatase TiO2 ...

Deposition of Porous Sorbents on Fabric Supports

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material that can be subsequently treated by dip coating. Dip coating with a sol preparation provides a supported porous layer on the fabric. In this case, the porous layer is a porphyrin functionalized sorbent system based on a powdered material that has been demonstrated previously for the capture and conversion of phosgene. A representative coating is applied to cotton fabric at a loading level of 10 mg/g. This coating has minimal impact on water vapor transport through the fabric (93% of the support fabric rate) while significantly reducing transport of 2-chloroethyl ethyl sulfide (CEES) through the material (7% of support fabric rate). The described approaches are suitable for use with other fabrics providing amine and hydroxyl groups for modification and can be used in combination with other sol preparations to produce varying functionality.

This report details a microwave-initiated approach for deposition of porphyrin functionalized porous organosilicate sorbents on a cotton fabric and demonstrates reduction in 2-chloroethyl ethyl sulfide (CEES) transport through the fabric resulting from this treatment.

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material ...

Preparation of Functional Silica Using a Bioinspired Method

The goal of the protocols described herein is to synthesize bioinspired silica materials, perform enzyme encapsulation therein, and partially or totally purify the same by acid elution. By combining sodium silicate with a polyfunctional bioinspired additive, silica is rapidly formed at ambient conditions upon neutralization. 
The effect of neutralization rate and biomolecule addition point on silica yield are investigated, and biomolecule immobilization efficiency is reported for varying addition point. In contrast to other porous silica synthesis methods, it is shown that the mild conditions required for bioinspired silica synthesis are fully compatible with the encapsulation of delicate biomolecules. Additionally, mild conditions are used across all synthesis and modification steps, making bioinspired silica a promising target for the scale-up and commercialization as both a bare material and active support medium.
The synthesis is shown to be highly sensitive to conditions, i.e., the neutralization rate and final synthesis pH, however tight control over these parameters is demonstrated through the use of auto titration methods, leading to high reproducibility in reaction progression pathway and yield. 
Therefore, bioinspired silica is an excellent active material support choice, showing versatility towards many current applications, not limited to those demonstrated here, and potency in future applications.

Here, we present a protocol to synthesize bioinspired silica materials and immobilize enzymes therein. Silica is synthesized by combining sodium silicate and an amine &#39;additive&#39;, which neutralize at a controlled rate. Material properties and function can be altered either by in situ enzyme immobilization or post-synthetic acid elution of encapsulated additives.

The goal of the protocols described herein is to synthesize bioinspired silica materials, perform enzyme encapsulation therein, and partially or totally ...

Multiscale Structures Aggregated by Imprinted Nanofibers for Functional Surfaces

Multiscale surface structures have attracted increasing interest owing to several potential applications in surface devices. However, an existing challenge in the field is the fabrication of hybrid micro-nano structures using a facile, cost-effective, and high-throughput method. To overcome these challenges, this paper proposes a protocol to fabricate multiscale structures using only an imprint process with an anodic aluminum oxide (AAO) filter and an evaporative self-aggregation process of nanofibers. Unlike previous attempts that have aimed to straighten nanofibers, we demonstrate a unique fabrication method for multiscale aggregated nanofibers with high aspect ratios. Furthermore, the surface morphology and wettability of these structures on various liquids were investigated to facilitate their use in multifunctional surfaces.

Presented is an easy method to fabricate nano-micro multiscale structures, for functional surfaces, by aggregating nanofibers fabricated using an anodic aluminum oxide filter.

Multiscale surface structures have attracted increasing interest owing to several potential applications in surface devices. However, an existing ...

Photopatterning Proteins and Cells in Aqueous Environment Using TiO2 Photocatalysis

Organic contaminants adsorbed on the surface of titanium dioxide (TiO2) can be decomposed by photocatalysis under ultraviolet (UV) light. Here we describe a novel protocol employing the TiO2 photocatalysis to locally alter cell affinity of the substrate surface. For this experiment, a thin TiO2 film was sputter-coated on a glass coverslip, and the TiO2 surface was subsequently modified with an organosilane monolayer derived from octadecyltrichlorosilane (OTS), which inhibits cell adhesion. The sample was immersed in a cell culture medium, and focused UV light was irradiated to an octagonal region. When a neuronal cell line PC12 cells were plated on the sample, cells adhered only on the UV-irradiated area. We further show that this surface modification can also be performed in situ, i.e., even when cells are growing on the substrate. Proper modification of the surface required an extracellular matrix protein collagen to be present in the medium at the time of UV irradiation. The technique presented here can potentially be employed in patterning multiple cell types for constructing coculture systems or to arbitrarily manipulate cells under culture.

Photopatterning Proteins and Cells in Aqueous Environment Using TiO2 Photocatalysis

We describe a protocol for modifying cell affinity of a scaffold surface in aqueous environment. The method takes advantage of titanium dioxide photocatalysis to decompose organic film in the photo-irradiated region. We show that it can be used to create microdomains of scaffolding proteins, both ex situ and in situ.

Organic contaminants adsorbed on the surface of titanium dioxide (TiO2) can be decomposed by photocatalysis under ultraviolet (UV) light. Here we describe ...

The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight

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