Quadruple Shape-Memory Organohydrogels with Adjustable Trigger Temperatures
Esra Su1,2, Cigdem Buse Oral2, Oguz Okay2
1Faculty of Aquatic Sciences, Istanbul University, Fatih, Istanbul 34134, Turkey.
ACS Omega
|September 2, 2025
Summary
New organohydrogels (OHGs) combine silk fibroin with alkyl acrylates for robust, adaptable materials. A novel "gluing method" enables quadruple shape-memory effects in these advanced soft materials.
Area of Science:
- Materials Science
- Polymer Chemistry
- Soft Matter Physics
Background:
- Organohydrogels (OHGs) are biphasic soft materials with hydrophilic and hydrophobic domains, enabling interaction with diverse solvents.
- Their unique properties lend themselves to applications in biomedicine, antifreeze, soft robotics, and environmental engineering.
Purpose of the Study:
- To develop novel organohydrogel systems based on silk fibroin and semicrystalline poly-(n-alkyl acrylates).
- To investigate the mechanical, viscoelastic, and shape-memory properties of these OHGs.
- To overcome challenges in achieving multi-shape-memory behavior caused by hydrophobic domain cocrystallization.
Main Methods:
- Fabrication of OHGs by dispersing single, binary, or ternary combinations of poly-(n-tetradecyl acrylate) (PC14A), poly-(n-hexadecyl acrylate) (PC16A), and poly-(n-octadecyl acrylate) (PC18A) micro-organogels within a silk fibroin hydrogel phase.
- Compression testing to evaluate mechanical strength and Young's modulus.
- Thermosensitive characterization of viscoelastic and mechanical properties.
- Development and application of a "gluing method" to prevent hydrophobic layer mixing and enable controlled cocrystallization.
Main Results:
- The synthesized OHGs exhibit high compressive strength (90-94% compression) and a high Young's modulus (up to 2.3 MPa).
- These materials demonstrate thermosensitive viscoelasticity and effective shape-memory effects with tunable trigger temperatures.
- Cocrystallization of hydrophobic poly-(n-alkyl acrylates) in dimer or trimer combinations hindered multi-shape-memory behavior.
- The "gluing method" successfully produced OHGs with quadruple shape-memory behavior, featuring trigger temperatures at 40, 30, and 15 °C.
Conclusions:
- Silk fibroin-based organohydrogels with tunable side-chain lengths offer exceptional mechanical properties and shape-memory capabilities.
- The developed "gluing method" is crucial for achieving complex, multi-stage shape-memory effects by controlling hydrophobic domain interactions.
- These advanced OHGs hold significant potential for sophisticated applications requiring adaptable and resilient soft materials.
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