Name: Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification (Video) | JoVE Journal
Uploaded: 2017-04-07T14:00:00.000+00:00
Duration: 7 min 32 s
Description: Learn to prepare and characterize zwitterionic hydrogel films and impregnated membranes for water purification. This simple, scalable method enables industrial production of antifouling membranes with effective transport properties.

ai_agent_IP

ai_agent

maintenance

instantTrialDurationMinutes

isBiopharma

enableNewMyJoveSectionDesign

educationFeatures

seoMetaApi

ai_copilot_institution_blacklist

ai_chat_institution_blacklist

freeAccessWindow

ssoRoleCapture

scheduledMaintenanceBanner

joveLabsFeatures

disable_autoplay_for_bots

extended_trial_duration

5 minutes

We gratefully acknowledge the financial support of this work by the Korean Carbon Capture and Sequestration R&amp;D Center (KCRC).

1. Preparation of the Prepolymer Solutions
<ol>
	<li>Preparation using water as a solvent
	<ol>
		<li>Add 10.00 g of deionized (DI) water to a glass bottle with a magnetic stir bar.</li>
		<li>Measure 2.00 g of SBMA and transfer it to the glass bottle containing the water. Stir the solution for 30 min, until the SBMA is completely dissolved.</li>
		<li>In a separate bottle, add 20.00 g of PEGDA (Mn = 700 g/mol).</li>
		<li>Add 20.0 mg of 1-hydroxycyclohexyl phenyl ketone (HCPK), a photo-initiator, to the PEGDA solution. Let the solution stir for at least 30 min.</li>
		<li>Using a disposable pipette, transfer 8.00 g of the PEGDA-HCPK solution to the SBMA aqueous solution. Continuously stir the mixture until the solution is homogenous.</li>
	</ol>
	</li>
	<li>Preparation using water/ethanol mixtures as solvents
	<ol>
		<li>Add 6.00 g of DI water and 4.00 g of ethanol to an amber glass bottle with a magnetic stir bar. Stir the solution to allow thorough mixing.</li>
		<li>Add 2.00 g of SBMA to the water/ethanol mixture. Stir the solution and allow the SBMA to completely dissolve.</li>
		<li>Use a pipette to transfer 8.00 g of the PEGDA-HCPK solution to the SBMA mixture. Stir to mix the solution thoroughly.</li>
	</ol>
	</li>
</ol>
2. Preparation of the Freestanding Films
<ol>
	<li>Place two spacers with known thicknesses on a clean quartz disc; the thickness of the spacers controls the thickness of the obtained polymer films19.</li>
	<li>Transfer a small amount (~1.0 mL) of the prepolymer solution to the quartz disc using a disposable pipette.</li>
	<li>Place another quartz disc on top of the liquid and ensure that there are no bubbles in the liquid film.</li>
	<li>Place the sample in an ultraviolet (UV) crosslinker and irradiate for 5 min using UV light with a wavelength of 254 nm19. 
	NOTE: Alternative irradiation times and wavelengths can be used depending on the type of photoinitiator.</li>
	<li>Separate the polymer film from the quartz discs using a sharp blade. Use tweezers to transfer the film to a DI water bath. Change the water twice during the first 24 h to remove the solvent, unreacted monomer/crosslinker, and sol from the film. 
	NOTE: The polymer film should be kept in the DI water to preserve the pore structure, if there is any.</li>
	<li>Prepare dried films for ATR-FTIR and DSC analysis.
	<ol>
		<li>Remove the film from the water bath and allow it to air dry for 24 h.</li>
		<li>Place the film in a vacuum oven at 80 °C to dry overnight under vacuum.</li>
	</ol>
	</li>
</ol>
3. Preparation of the Impregnated Membranes
<ol>
	<li>Place a sheet of porous support onto a quartz disc.</li>
	<li>Using a foam brush, coat each side of the support twice with the prepolymer solution based on the water/ethanol mixture4. 
	NOTE: Since the support is hydrophobic, the prepolymer solution containing ethanol can easily wet the support.</li>
	<li>Place another quartz disc on top of the support.</li>
	<li>Place the sample in a UV crosslinker and irradiate for 5 min using UV light with a wavelength of 254 nm.</li>
	<li>To remove the impregnated membrane from the quartz discs, immerse the whole assembly in a DI water bath for 5 min and carefully remove the membrane using a sharp blade and tweezers.</li>
	<li>Keep the membrane in DI water. Change the water twice to remove the solvent, the unreacted monomer/crosslinker, and the sol from the membrane.</li>
	<li>Prepare dried, impregnated membranes for ATR-FTIR and DSC analyses.
	<ol>
		<li>Remove the membrane from the water bath. Allow the membrane to dry at ambient conditions for 24 h.</li>
		<li>Dry the membrane in a vacuum oven overnight at 80 °C under vacuum.</li>
	</ol>
	</li>
</ol>
4. Characterization of the Freestanding Films and Impregnated Membranes
<ol>
	<li>ATR-FTIR analysis
	<ol>
		<li>Prepare a sample of the prepolymer solution, as stated in step 1.1, for FTIR analysis.</li>
		<li>Perform a background scan before scanning the sample. Set the wavenumber range from 600 cm-1 to 4,500 cm-1 at a 4-cm-1 resolution of measurement.</li>
		<li>Place the sample in the FTIR machine for analysis.</li>
		<li>Remove the sample. Clean the crystal and the tip with an appropriate solvent.</li>
		<li>Repeat steps 4.1.1 - 4.1.4 for the following samples: porous support, prepolymer solution, dried freestanding films, and dried impregnated membranes.</li>
	</ol>
	</li>
	<li>Differential scan calorimetry (DSC)
	<ol>
		<li>Place a DSC pan and lid in a weighing balance and record their weight.</li>
		<li>Place a small amount of sample (5-10 mg) inside the pan and close it with the lid.</li>
		<li>Weigh the pan containing the sample. From the weight difference between the occupied pan and lid and the unoccupied pan and lid, calculate the weight of the sample.</li>
		<li>Using a press, hermetically seal the sample inside the pan.</li>
		<li>Place the sealed pan inside the DSC cell in which the inert reference is located.</li>
		<li>Enter the weight of the unoccupied pan and lid and the weight of the sample in the program.</li>
		<li>Scan with the DSC from -80 °C to 160 °C at a heating rate of 10 °C/min.</li>
		<li>Perform the DSC analysis using the manufacturer's protocol.</li>
		<li>Repeat the DSC experiments for different samples following the aforementioned steps.</li>
	</ol>
	</li>
	<li>Measurement of contact angles using a pendant drop method
	<ol>
		<li>Cut a rectangular strip of the membrane sample (approximately 30 mm by 6 mm).</li>
		<li>Soak this strip in DI water for 10 min and then dry it for 5 min.</li>
		<li>Place the dried sample on the sample holder.</li>
		<li>Submerge the sample holder in a transparent environmental chamber containing the DI water20.</li>
		<li>Using a microliter syringe with a stainless steel needle, dispense drops of n-decane (approximately 1 µL) onto the membrane sample.</li>
		<li>Leave the setup undisturbed for 2 min to ensure the stabilization of the droplets.</li>
		<li>Use an appropriate image analysis software to determine the contact angle of the samples by measuring the angles of the dispensed droplets on the membrane surface.</li>
		<li>Take the average of the contact angle values obtained for various droplets.</li>
	</ol>
	</li>
	<li>Characterization of water permeability using a dead-end filtration system
	<ol>
		<li>Use a hammer-driven hole punch with an appropriate diameter to cut coupons of freestanding films and impregnated membranes.</li>
		<li>Place a prepared coupon on the porous support inside a dead end filtration cell.</li>
		<li>Place the O-ring on top of the sample. Screw the two halves of the permeation cell together.</li>
		<li>Add approximately 50 mL of DI water to the permeation cell. Screw on the cap and place the permeation cell on a magnetic stirrer. Set the stirring rate between 300 and 900 rpm.</li>
		<li>Place a covered beaker on a balance to collect the permeate water. Tare the balance.</li>
		<li>Open the valve on the gas cylinder. Turn the pressure regulator valve clockwise until the desired pressure is reached (45 psig for freestanding films and 35 psig for impregnated membranes).</li>
		<li>Open the release valve to deliver the pressure to the permeation cell.</li>
		<li>Monitor and record the weight of the beaker with time.</li>
		<li>Calculate the water permeance (Aw) and permeability (Pw) with the solution-diffusion model shown below4,21 
		<img alt="Water activity and permeability equations, mathematical formula for mass transfer analysis." src="/files/ftp_upload/55426/55426eq1.jpg" data-altupdatedat="1788250015000" data-alt="Equation"> 
		where Aw is the water permeance (L/m2hbar or LMH/bar), Pw is the water permeability (LMH cm/bar), ρw is the water density (g/L), A is the effective area of the membrane (m2), Δm is the change in the mass of water permeate (g) over a time period Δt (h), Δp is the pressure difference across the membrane (bar), and l is the thickness of the swollen film (cm).</li>
		<li>Use a BSA solution containing 0.5 g/L BSA in a phosphate-buffered saline (PBS) solution with pH = 7.4 to evaluate the antifouling properties and rejection rates of the membranes.</li>
		<li>Repeat steps 4.4.5 - 4.4.10 to determine the water flux in the presence of BSA. Calculate the BSA rejection rate with the following equation22 
		<img alt="BSA rejection formula, \( R_{BSA}(\%) = (1 - \frac{C_P}{C_F}) \times 100\% \), calculation method." src="/files/ftp_upload/55426/55426eq2.jpg" data-altupdatedat="1788250015000" data-alt="Equation"> 
		where RBSA is the BSA rejection rate of the membrane (%), CP is the concentration of BSA in the permeate (g/L), and CF is the concentration of BSA in the feed (g/L); the concentration of BSA can be determined via UV spectroscopy.</li>
	</ol>
	</li>
</ol>

<ol><li>Qasim, M., Darwish, N. A., Sarp, S., Hilal, N. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0011916415300242">Water desalination by forward (direct) osmosis phenomenon: A comprehensive review.</a> Desalination. , 47-69 (2015).</li>
<li>Geise, G. M., et al. <a target="_blank" href="http://onlinelibrary.wiley.com/doi/10.1002/polb.22037/full">Water purification by membranes: The role of polymer science.</a> J. Polym. Sci. Part B Polym. Phys. 48 (15), 1685-1718 (2010).</li>
<li>Miller, D. J., Dreyer, D., Bielawski, C., Paul, D. R., Freeman, B. D. <a target="_blank" href="http://onlinelibrary.wiley.com/doi/10.1002/anie.201601509/full">Surface modification of water purification membranes: A review.</a> Angew Chem Int Ed Engl. , (2016).</li>
<li>Zhao, S. Z., Huang, K. P., Lin, H. Q. <a target="_blank" href="http://pubs.acs.org/doi/abs/10.1021/acs.iecr.5b03241">Impregnated Membranes for Water Purification Using Forward Osmosis.</a> Ind. Eng. Chem. Res. 54 (49), 12354-12366 (2015).</li>
<li>Ostuni, E., Chapman, R. G., Holmlin, R. E., Takayama, S., Whitesides, G. M. <a target="_blank" href="http://pubs.acs.org/doi/abs/10.1021/la010384m">A survey of structure-property relationships of surfaces that resist the adsorption of protein.</a> Langmuir. 17 (18), 5605-5620 (2001).</li>
<li>Jiang, S., Cao, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Ultralow-fouling%2C+functionalizable%2C+and+hydrolyzable+zwitterionic+materials+and+their+derivatives+for+biological+applications%5BTitle%5D)+AND+%22Adv+Mat%22%5BJournal%5D)">Ultralow-fouling, functionalizable, and hydrolyzable zwitterionic materials and their derivatives for biological applications.</a> Adv Mat. 22 (9), 920-932 (2010).</li>
<li>Shah, S., et al. <a target="_blank" href="http://onlinelibrary.wiley.com/doi/10.1002/polb.24096/abstract">Transport properties of small molecules in zwitterionic polymers.</a> J. Polym. Sci. Part B Polym. Phys. 54 (19), 1924-1934 (2016).</li>
<li>Shao, Q., Jiang, S. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Molecular+Understanding+and+Design+of+Zwitterionic+Materials%5BTitle%5D)+AND+%22Adv+Mat%22%5BJournal%5D)">Molecular Understanding and Design of Zwitterionic Materials.</a> Adv Mat. 27 (1), 15-26 (2015).</li>
<li>Zhang, Z., Chao, T., Chen, S., Jiang, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Superlow+Fouling+Sulfobetaine+and+Carboxybetaine+Polymers+on+Glass+Slides%5BTitle%5D)+AND+%22Langmuir%22%5BJournal%5D)">Superlow Fouling Sulfobetaine and Carboxybetaine Polymers on Glass Slides.</a> Langmuir. 22 (24), 10072-10077 (2006).</li>
<li>Chen, S., Li, L., Zhao, C., Zheng, J. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0032386110006968">Surface hydration: principles and applications toward low-fouling/nonfouling biomaterials.</a> Polymer. 51 (23), 5283-5293 (2010).</li>
<li>Bengani, P., Kou, Y. M., Asatekin, A. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0376738815300533">Zwitterionic copolymer self-assembly for fouling resistant, high flux membranes with size-based small molecule selectivity.</a> J Membr Sci. 493, 755-765 (2015).</li>
<li>Chiang, Y. C., Chang, Y., Chuang, C. J., Ruaan, R. C. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0376738811007678">A facile zwitterionization in the interfacial modification of low bio-fouling nanofiltration membranes.</a> J Membr Sci. 389, 76-82 (2012).</li>
<li>Mi, Y. F., Zhao, Q., Ji, Y. L., An, Q. F., Gao, C. J. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0376738815004111">A novel route for surface zwitterionic functionalization of polyamide nanofiltration membranes with improved performance.</a> J Membr Sci. 490, 311-320 (2015).</li>
<li>Shafi, H. Z., Khan, Z., Yang, R., Gleason, K. K. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0011916415000855">Surface modification of reverse osmosis membranes with zwitterionic coating for improved resistance to fouling.</a> Desalination. 362, 93-103 (2015).</li>
<li>Yang, R., Goktekin, E., Gleason, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Zwitterionic+Antifouling+Coatings+for+the+Purification+of+High-Salinity+Shale+Gas+Produced+Water%5BTitle%5D)+AND+%22Langmuir%22%5BJournal%5D)">Zwitterionic Antifouling Coatings for the Purification of High-Salinity Shale Gas Produced Water.</a> Langmuir. 31 (43), 11895-11903 (2015).</li>
<li>Yang, R., Jang, H., Stocker, R., Gleason, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Synergistic+Prevention+of+Biofouling+in+Seawater+Desalination+by+Zwitterionic+Surfaces+and+Low-Level+Chlorination%5BTitle%5D)+AND+%22Adv+Mat%22%5BJournal%5D)">Synergistic Prevention of Biofouling in Seawater Desalination by Zwitterionic Surfaces and Low-Level Chlorination.</a> Adv Mat. 26 (11), 1711-1718 (2014).</li>
<li>Azari, S., Zou, L. D. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0376738812000701">Using zwitterionic amino acid L-DOPA to modify the surface of thin film composite polyamide reverse osmosis membranes to increase their fouling resistance.</a> J Membr Sci. 401, 68-75 (2012).</li>
<li>Chang, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Underwater+Superoleophobic+Surfaces+Prepared+from+Polymer+Zwitterion%2FDopamine+Composite+Coatings%5BTitle%5D)+AND+%22Adv+Mater+Inter%22%5BJournal%5D)">Underwater Superoleophobic Surfaces Prepared from Polymer Zwitterion/Dopamine Composite Coatings.</a> Adv Mater Inter. , (2016).</li>
<li>Lin, H., Kai, T., Freeman, B. D., Kalakkunnath, S., Kalika, D. S. <a target="_blank" href="http://pubs.acs.org/doi/abs/10.1021/ma0510136">The Effect of Cross-Linking on Gas Permeability in Cross-Linked Poly(Ethylene Glycol Diacrylate).</a> Macromolecules. 38 (20), 8381-8393 (2005).</li>
<li>Sagle, A. C., Ju, H., Freeman, B. D., Sharma, M. M. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0032386108010884">PEG-based hydrogel membrane coatings.</a> Polymer. 50 (3), 756-766 (2009).</li>
<li>Wu, Y. -H., Park, H. B., Kai, T., Freeman, B. D., Kalika, D. S. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0376738809007674">Water uptake, transport and structure characterization in poly(ethylene glycol) diacrylate hydrogels.</a> J Membr Sci. 347 (1-2), 197-208 (2010).</li>
<li>Rahimpour, A., et al. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0011916411009271">Novel functionalized carbon nanotubes for improving the surface properties and performance of polyethersulfone (PES) membrane.</a> Desalination. 286, 99-107 (2012).</li>
<li>Gulmine, J. V., Janissek, P. R., Heise, H. M., Akcelrud, L. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0142941801001246">Polyethylene characterization by FTIR.</a> Polym Testing. 21 (5), 557-563 (2002).</li>
<li>Araújo, J. R., Waldman, W. R., De Paoli, M. A. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0141391008002516">Thermal properties of high density polyethylene composites with natural fibres: Coupling agent effect.</a> Polym. Degrad. Stab. 93 (10), 1770-1775 (2008).</li>
<li>McCloskey, B. D., et al. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0032386110004106">Influence of polydopamine deposition conditions on pure water flux and foulant adhesion resistance of reverse osmosis, ultrafiltration, and microfiltration membranes.</a> Polymer. 51 (15), 3472-3485 (2010).</li>
</ol>

The authors declare that they have no competing financial interests.

We have demonstrated a facile method to prepare freestanding films and impregnated membranes based on zwitterionic hydrogels. The disappearance of three (meth)acrylate characteristic peaks (i.e., 810, 1,190, and 1,410 cm-1) in the IR spectra of the obtained polymer films and impregnated membrane (Figure 2) indicates the good conversion of the monomers and crosslinker4,19,21. Additionally, the...

There is a great need to develop low cost and energy efficient technologies to produce clean water in order to meet the increasing demand. Polymeric membranes have emerged as a leading technology for water purification due to their inherent advantages, such as their high energy efficiency, low cost, and simplicity in operation1. Membranes allow pure water to permeate through and reject the contaminants. However, membranes are often subjected to fouling by contaminants in the feed water, which can be adsorbed onto the membrane surface from their favorable interactions2,3. The fouling can dramatically decrease water flux through the membranes, increasing the membrane area required and the cost of water purification.
An effective approach to mitigate fouling is to modify the membrane surface to increase the hydrophilicity and thus decrease the favorable interactions between the membrane surface and foulants. One method is to use thin-film coating with superhydrophilic3 hydrogels. The hydrogels often have high water permeability; therefore, a thin-film coating can increase the long-term water permeance through the membrane due to the mitigated fouling, despite the slightly increased transport resistance across the whole membrane. The hydrogels can also be directly fabricated into impregnated membranes for water purification in osmotic applications4.
Zwitterionic materials contain both positively and negatively charged functional groups, with a net neutral charge, and have strong surface hydration through electrostatic-induced hydrogen bonding5,6,7,8,9. The tightly bound hydration layers act as physical and energy barriers, preventing foulants from attaching onto the surface, thus demonstrating excellent antifouling properties10. Zwitterionic polymers, such as poly(sulfobetaine methacrylate) (PSBMA) and poly(carboxybetaine methacrylate) (PCBMA), have been used to modify the membrane surface by coating11,12,13,14,15,16,17,18 to increase surface hydrophilicity and thus antifouling properties.
We demonstrate here a facile method to prepare zwitterionic hydrogels using sulfobetaine methacrylate (SBMA) via photopolymerization, which is crosslinked using poly(ethylene glycol) diacrylate (PEGDA, Mn = 700 g/mol) to improve the mechanical strength. We also present a procedure to construct robust membranes by impregnating the monomer and crosslinker in a highly porous hydrophobic support before the photopolymerization. The physical and water transport properties of the freestanding films and impregnated membranes are thoroughly characterized to elucidate the structure/property relationship for water purification. The prepared hydrogels can be used as a surface coating to enhance membrane separation properties. By adjusting the crosslinking density or by impregnating into hydrophobic porous supports, these materials can also form thin films with sufficient mechanical strength for osmotic processes, such as forward osmosis or pressure-retarded osmosis4.

<table><tbody><tr><td>Poly(ethylene glycol) diacrylate&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; M&lt;sub&gt;n&lt;/sub&gt; = 700 (PEGDA)</td><td>Sigma Aldrich</td><td>455008</td><td></td></tr><tr><td>1-Hydroxycyclohexyl phenyl ketone, 99% (HCPK)</td><td>Sigma Aldrich</td><td>405612</td><td></td></tr><tr><td>[2-(Methacrloyloxy)ethyl dimethyl-(3-sulfopropyl) ammonium hydroxide, 97%</td><td>Sigma Aldrich</td><td>537284</td><td>Acutely Toxic</td></tr><tr><td>Ethanol, 95%</td><td>Koptec, VWR International</td><td>V1101</td><td>Flamable</td></tr><tr><td>Decane, anhydrous, 99%</td><td>Sigma Aldrich</td><td>457116</td><td></td></tr><tr><td>Solupor Membrane</td><td>Lydall</td><td>7PO7D</td><td></td></tr><tr><td>Micrometer&amp;nbsp;</td><td>Starrett</td><td>2900-6</td><td></td></tr><tr><td>ATR-FTIR</td><td>Vertex 70</td><td></td><td></td></tr><tr><td>DSC: TA Q2000</td><td>TA Instruments</td><td></td><td></td></tr><tr><td>Rame&amp;rsquo;-hart Goniometer: Model 190</td><td>Rame&amp;rsquo;-hart Instruments</td><td></td><td></td></tr><tr><td>Ultraviolet Crosslinker: CX-2000</td><td>Ultra-Violet Products</td><td></td><td>UV radiation&amp;nbsp;</td></tr><tr><td>Permeation Cell: Model UHP-43</td><td>Advantec MFS</td><td></td><td></td></tr><tr><td>Deionized Water: Milli-Q Water</td><td>EMD Millipore</td><td></td><td></td></tr></tbody></table>

synthesis of hydrogels with antifouling properties as membranes for water purification

Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and thus achieving stable water permeability through membranes over time. Here, we report a facile method to prepare hydrogels based on zwitterions for membrane applications. Freestanding films can be prepared from sulfobetaine methacrylate (SBMA) with a crosslinker of poly(ethylene glycol) diacrylate (PEGDA) via photopolymerization. The hydrogels can also be prepared by impregnation into hydrophobic porous supports to enhance the mechanical strength. These films can be characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to determine the degree of conversion of the (meth)acrylate groups, using goniometers for hydrophilicity and differential scanning calorimetry (DSC) for polymer chain dynamics. We also report protocols to determine the water permeability in dead-end filtration systems and the effect of foulants (bovine serum albumin, BSA) on membrane performance.

Freestanding films prepared with the prepolymer solutions specified in steps 1.1 and 1.2 are referred to as S50 and S30, respectively. Detailed information is shown in Table 1. The prepolymer solution specified in step 1.2 was also used to fabricate impregnated membranes, which are denoted as IMS30. Because the porous support is made of hydrophobic polyethylene, only the prepolymer solution containing ethanol can be impre...

This paper reports practical methods to prepare hydrogels in freestanding films and impregnated membranes and to characterize their physical properties, including water transport properties.

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and ...

The overall goal of this procedure is to prepare and characterize freestanding films and impregnated membranes based on zwitterionic hydrogels for membrane water purification. This method provide guidance for repairing hydrogel base freestanding film in impregnated membrane and as well as for characterizing their physical and transport properties. The main advantage of this technique is that it's simple, fast, and easy to be scaled up in industrial production.Visual demonstration of this method is critical as the integrated hydrogel preparation and characterization steps are difficult to learn because custom built apparatus is used, and interdisciplinary skills are required. To prepare the freestanding films, first place two spacers of known thickness on a clean quartz disc. The thickness of the spacers controls the thickness of the obtained polymer films.Transfer a small amount of the pre-polymer solution to the quartz disc using a disposable pipette. Place another quartz disc on top of the liquid and ensure that there are no bubbles in the liquid film. Then, place the sample in an ultraviolet or UV crosslinker and irradiate it for five minutes using UV light with a wavelength of 254 nanometers.When the polymer film is removed from the quartz disc, it is critical to work slowly to avoid tearing the film. Separate the polymer film from the quartz discs using a sharp blade. Use tweezers to transfer the film to a deionized water bath.Change the water twice during the first 24 hours to remove the solvent, unreacted monymer and crosslinker, and solve from the film. To prepare dried films for analysis, remove the film from the water bath and allow it to air dry for 24 hours. Place the film in a vacuum oven at 80 degrees Celsius to dry overnight under vacuum.Place a sheet of porous support onto a quartz disc. Using a foam brush, coat each side of the support twice with a prepolymer solution that is based on the water ethanol mixture. Place another quartz disc on top of the support.Then place the sample in a UV crosslinker and irradiate it for five minutes using UV light with a wavelength of 254 nanometers. To remove the impregnated membrane from the quartz discs, immerse the whole assembly in a deionized water bath for five minutes and carefully remove the membrane using a sharp blade and tweezers. Keeping the membrane in deionized water, change the water twice to remove the solvent, the unreacted monymer and crosslinker, and the sol from the membrane.To prepare dried, impregnated membranes for analysis, remove the membrane from the water bath, allow the membrane to dry at ambient conditions for 24 hours. Then, dry the membrane in a vacuum oven overnight at 80 degrees Celsius under vacuum. To measure the contact angles using the pendant drop method, first cut a rectangular strip of the membrane sample.Soak this strip in deionized water for 10 minutes. And then dry it for five minutes. Place the dried sample on the sample holder.Then, submerge the sample holder in a transparent environmental chamber containing the deionized water. In the next step, it is critical to work slowly and dispensing the n-decane drops onto the membranes. Using a microliter syringe with a stainless steel needle, dispense drops of n-decane onto the membrane sample.Leave the setup undisturbed for two minutes to ensure the stabilization of the droplets. Next, use appropriate image analysis software to determine the contact angle of the samples by measuring the angles of the dispensed droplets on the membrane surface. To characterize the water permeability using a dead end filtration system, first cut coupons of freestanding films and impregnated membranes with a hammer driven hole punch of an appropriate diameter.Place a prepared coupon on the porous support inside a dead end filtration cell. Then, place the O ring on top of the sample. Screw the two halves of the permeation cell together.Next, add approximately 50 milliliters of deonized water to the permeation cell. Screw on the cap and place the permeation cell on a magnetic stirrer. Set the stirring rate to between 300 and 900 RPM.Then, place a covered beaker on a balance to collect the permeate water and tear the balance. Open the valve on the gas cylinder. Turn the pressure regulator valve clockwise until the desired pressure is reached.Finally, open the release valve to deliver the pressure to the permeation cell. Monitor and record the weight of the beaker with time. Shown here are photos of the freestanding film, porous support, and impregnated membranes.It is evidence that after the porous support is filled with the hydrogel, it changes from opaque to transparent. The infrared spectra indicate the almost complete conversion of the acryllate groups in the hydrogels. Due to the absence of acryllate characteristic peaks in the spectra.The glass transition temperature of hydrogels is determined by differential scan calorimetry as shown here. Lower contact angles in the freestanding films and impregnated membranes indicate the greater hydrophilicity than the porous support. After watching this video you should have a good understanding of how to repair hydrogel base materials and characterize their properties.This work describes a faster method to fabricate hydrogel based material via photopolymerizations as well as how to characterize them for water purification. The method and material may also be used to repair membrane for gas operations such as CO2 capture. Don't forget that working with chemical and UV radiation can be extremely hazardous and precautions such as personal protective equipment should always be taken while performing this procedure.

synthesis-hydrogels-with-antifouling-properties-as-membranes-for

Research

JoVE Journal

Bioengineering

We present the synthesis of a split-intein-mediated protein hydrogel. The building blocks of this hydrogel are two protein copolymers each containing a subunit of a trimeric protein that serves as a crosslinker and one half of a split intein. Mixing of the two protein copolymers triggers an intein trans-splicing reaction, yielding a polypeptide unit that self-assembles into a hydrogel. This hydrogel is highly pH- and temperature-stable, compatible with organic solvents, and easily incorporates...

Synthesis of an Intein-mediated Artificial Protein Hydrogel

A plasma-induced polymerization procedure is described for the surface-initiated polymerization on polymer membranes. Further postmodification of the grafted polymer with photochromic substances is presented with a protocol of conducting permeability measurements of light-responsive membranes.

Preparation of Light-responsive Membranes by a Combined Surface Grafting and Postmodification Process

Two- and three-dimensional superhydrophobic polymeric materials are prepared by electrospinning or electrospraying biodegradable polymers blended with a lower surface energy polymer of similar composition.

Fabricating Superhydrophobic Polymeric Materials for Biomedical Applications

Design and fabrication of a three-dimensionally (3-D) printed microfluidic cross-flow filtration system is demonstrated. The system is used to test performance and observe fouling of ultrafiltration and nanofiltration (thin film composite) membranes.

Three-Dimensionally Printed Microfluidic Cross-flow System for Ultrafiltration/Nanofiltration Membrane Performance Testing

Protocols are described for the fabrication of degradable thermoresponsive hydrogels based on hydrazone cross-linking of polymeric oligomers on the bulk scale, microscale, and nanoscale, the latter for preparation of both gel nanoparticles and nanofibers.

Fabricating Degradable Thermoresponsive Hydrogels on Multiple Length Scales via Reactive Extrusion, Microfluidics, Self-assembly, and Electrospinning

A simple, reproducible, and versatile approach for the synthesis of intergrown, polycrystalline metal-organic framework membranes on a wide range of unmodified porous and non-porous supports is presented.

Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes

Presented here is a stepwise protocol for realizing gas-entrapping membranes (GEMs) from SiO2/Si wafers using integrated circuit microfabrication technology. When silica-GEMs are immersed in water, the intrusion of water is prevented, despite the water-loving composition of silica.

Proof-of-Concept for Gas-Entrapping Membranes Derived from Water-Loving SiO2/Si/SiO2 Wafers for Green Desalination

We report a protocol for producing a hybrid lipid membrane at the water/air interface by doping the lipid bilayer with copper (II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (CuPc) molecules. The resulting hybrid lipid membrane has a lipid/CuPc/lipid sandwich structure. This protocol can also be applied to the formation of other functional nanomaterials.

Self-Assembly of Hybrid Lipid Membranes Doped with Hydrophobic Organic Molecules at the Water/Air Interface

The use of photodegradable hydrogels to isolate bacterial cells by utilizing a high-resolution light pattering tool is reported. Essential experimental procedures, results, and advantages of the process are reviewed. The method enables rapid and inexpensive isolation of targeted bacteria showing rare or unique functions from heterogeneous communities or populations.

Photodegradable Hydrogel Interfaces for Bacteria Screening, Selection, and Isolation

Here, we present two protocols for embedding cell-free protein synthesis reactions in macro-scale hydrogel matrices without the need for an external liquid phase.

Methods for Embedding Cell-Free Protein Synthesis Reactions in Macro-Scale Hydrogels

Learn to prepare and characterize zwitterionic hydrogel films and impregnated membranes for water purification. This simple, scalable method enables industrial production of antifouling membranes with effective transport properties.

Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification

Explore More Videos