@@ashwinisakhileti1444 Begin by adding 100 mL of reverse osmosis or deionized water to a 150 mL tall-form beaker. Place a thermometer in the beaker so the bulb rests on the bottom of the glassware, and heat the beaker on a standard hot plate until the water reaches 85-95 °C. While the water is warming, obtain 12 g of PVA with Mw ∼ 145,000 g mol-1 (i.e., Mowiol 28-99 from Millipore Sigma). Use of PVA with a larger Mw will not readily form homogeneous solutions in water at the desired concentration, and samples with a smaller Mw may not be sufficiently rigid to assess the ultimate tensile strength (cf., Supporting Information for further discussion). Because the PVA needs to be added portionwise, divide the solid into 8-10 roughly equal fractions. At this point, use a Hot Hand or insulated glove for handling hot glassware. Once the water has reached temperature and the temperature is stable, pour the entire volume of water into a graduated cylinder, quickly transfer 45-50 mL of the hot water back into the beaker, and continue heating on the hot plate. This step will ensure that the appropriate volume of water is present at the start of the experiment. Figure 2  Figure 2. Outline and timing for each phase of the activity. Grasp the warm beaker with a Hot Hand or insulated glove and begin vigorously hand stirring the water with a large spatula while a lab partner slowly adds the first portion of solid PVA. After the complete addition of the first portion of solid, continue to vigorously stir the resulting mixture for 2-3 min before adding the next portion of solid. Continue solid addition every 2-3 min with constant vigorous stirring and occasional temperature monitoring until all of the PVA has been added. After addition of PVA, the mixture will become viscous and opaque (cf., Figure 3a). After complete addition of the PVA solid, stir the mixture for an additional 2-3 min and transfer the resulting molten hydrogel into a mold (e.g., ice-cube tray) using a spatula, stirring rod, and/or thermometer. Attempt to prepare four uniform hydrogels by splitting the sticky and viscous PVA solution into four spaces of the mold (cf., Figure 3c). This approach will increase the likelihood of obtaining at least two hydrogel samples with measurable self-healing properties. After transfer of the material to the mold, cover it with aluminum foil, and, if possible, allow the material to sit in the mold and cool to room temperature for 1-3 h before freezing (cf., Figure 3d). Place the mold and hydrogel mixture in a −20 °C freezer for 1 h to freeze the hydrogels and induce crystallite formation (cf., Figure 3e). Move the materials from the freezer to a room temperature benchtop and allow the material to thaw, covered, in the mold at room temperature. After the material thaws for 12-24 h, carefully remove.
Does this only work with PVA? Im working with CNC and CNF i want to try this really interesting thanks for sharing
😶😔😔😔😔Even I tried making PVA hydrogel sir,,it ended up being a solution 😔
Hello! I am trying to make pva hydrogel through freeze thaw cycles but it just turns back into solution. Can you please guide me?
Hi please take a look at our publication on this work!
pubs.acs.org/doi/abs/10.1021/acs.jchemed.9b00161
Can you please guide me?
@@wentzellab9707 couldn't access😔
@@ashwinisakhileti1444
Begin by adding 100 mL of reverse osmosis or deionized water to a 150 mL tall-form beaker. Place a thermometer in the beaker so the bulb rests on the bottom of the glassware, and heat the beaker on a standard hot plate until the water reaches 85-95 °C. While the water is warming, obtain 12 g of PVA with Mw ∼ 145,000 g mol-1 (i.e., Mowiol 28-99 from Millipore Sigma). Use of PVA with a larger Mw will not readily form homogeneous solutions in water at the desired concentration, and samples with a smaller Mw may not be sufficiently rigid to assess the ultimate tensile strength (cf., Supporting Information for further discussion). Because the PVA needs to be added portionwise, divide the solid into 8-10 roughly equal fractions. At this point, use a Hot Hand or insulated glove for handling hot glassware. Once the water has reached temperature and the temperature is stable, pour the entire volume of water into a graduated cylinder, quickly transfer 45-50 mL of the hot water back into the beaker, and continue heating on the hot plate. This step will ensure that the appropriate volume of water is present at the start of the experiment.
Figure 2

Figure 2. Outline and timing for each phase of the activity.
Grasp the warm beaker with a Hot Hand or insulated glove and begin vigorously hand stirring the water with a large spatula while a lab partner slowly adds the first portion of solid PVA. After the complete addition of the first portion of solid, continue to vigorously stir the resulting mixture for 2-3 min before adding the next portion of solid. Continue solid addition every 2-3 min with constant vigorous stirring and occasional temperature monitoring until all of the PVA has been added. After addition of PVA, the mixture will become viscous and opaque (cf., Figure 3a). After complete addition of the PVA solid, stir the mixture for an additional 2-3 min and transfer the resulting molten hydrogel into a mold (e.g., ice-cube tray) using a spatula, stirring rod, and/or thermometer. Attempt to prepare four uniform hydrogels by splitting the sticky and viscous PVA solution into four spaces of the mold (cf., Figure 3c). This approach will increase the likelihood of obtaining at least two hydrogel samples with measurable self-healing properties. After transfer of the material to the mold, cover it with aluminum foil, and, if possible, allow the material to sit in the mold and cool to room temperature for 1-3 h before freezing (cf., Figure 3d). Place the mold and hydrogel mixture in a −20 °C freezer for 1 h to freeze the hydrogels and induce crystallite formation (cf., Figure 3e). Move the materials from the freezer to a room temperature benchtop and allow the material to thaw, covered, in the mold at room temperature. After the material thaws for 12-24 h, carefully remove.
@@bensuslavich2319 Thank you!