SUMMARY:
UCLA researchers in the Department of Materials Science and Engineering have developed a method to create hydrogels with tunable strength, mechanical strain, toughness, and fatigue resistance.
BACKGROUND:
Hydrogels are used in a wide range of applications such as tissue engineering, drug delivery, and energy storage devices. But despite recent advances in improving hydrogel mechanical performance, it remains a challenge to produce simultaneously strong, tough, stretchable and fatigue-resistant hydrogels with more elaborate hierarchical structures across broader length scales, such as those observed in natural materials. This limits their use, as each hydrogel needs to be designed for a particular application. Methods to improve this have primarily focused on the composition of these materials, but do not allow for complex structures. Therefore, there is a need for a method of producing hydrogels with tunable mechanical properties by means of a generic and facile approach.
INNOVATION:
UCLA researchers have developed a method of generating hydrogel material with tunable mechanical properties through a combination of molecular and structural engineering approaches. By combining directional freeze-casting and a subsequent salting-out treatment, which synergistically create hydrogel structures on different length scales across the millimeter scale to the molecular level, they have constructed strong, tough, stretchable and fatigue-resistant hydrogels with hierarchical and anisotropic structures. The resulting hydrogels have a water content of 70–95 per cent and properties that compare favorably to those of other tough hydrogels and even natural tendons; for example, an ultimate stress of 23.5 ± 2.7 megapascals, strain levels of 2,900 ± 450 per cent, toughness of 210 ± 13 megajoules per cubic meter, fracture energy of 170 ± 8 kilojoules per square meter and a fatigue threshold of 10.5 ± 1.3 kilojoules per square meter. Furthermore, the method can also be adapted for other polymers. It can also be adapted to FDA-approved polymers, paving the way for use in biological systems.
POTENTIAL APPLICATIONS:
- Tissue engineering
- Toughening polymer agent
- 3D-printed hydrogel materials
- Tough coating for surgical tools
- Thyroplasty implant
- Vocal fold surgery
- Eye orbital muscle replacement
- Artificial muscles for soft robotics
ADVANTAGES:
- High robustness and durability
- Tunable material properties
- Biocompatible
- Easy to fabricate
- Can be coated onto objects with complex geometry
- Anti-freezing
STATUS OF DEVELOPMENT:
Proof-of-concept fabrication of hydrogels and rendered design have been created for the innovation.
DEMONSTRATION VIDEO:
Oscibot Swimming; Laboratory Website
RELATED MATERIALS:
Hua, Mutian, et al. "Strong tough hydrogels via the synergy of freeze-casting and salting out." Nature 590.7847 (2021): 594-599.
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