Biomimetic Multiscale Oriented PVA/NRL Hydrogel Enabled Multistimulus Responsive and Smart Shape Memory Actuator

Area of Science:

• Materials Science
• Polymer Science
• Biomaterials Engineering

Background:

• Shape memory hydrogels are promising for functional soft materials but often suffer from poor mechanical properties and low actuation strength.
• This limits their application in sophisticated devices like smart biomimetic systems.

Purpose of the Study:

• To develop a novel shape memory hydrogel with improved mechanical and shape memory characteristics.
• To create a muscle-inspired material with multiscale oriented structure for enhanced performance.

Main Methods:

• A strategy was developed using polyvinyl alcohol (PVA) and natural rubber latex (NRL) to create an oriented polyvinyl alcohol-natural rubber latex hydrogel (OPNH).
• The shape memory function was achieved through stretch-induced crystallization of natural rubber (NR), with PVA enhancing interactions with NRL particles.
• A multiscale-oriented structure was formed during a stretch-drying process.

Main Results:

• The OPNH exhibited excellent interfacial compatibility and outstanding mechanical performance (3.2 MPa).
• High shape fixity (≈80%) and shape recovery ratio (≈92%) were achieved.
• The hydrogel demonstrated high actuation strength (206 kPa), significant working capacity (105 kJ m⁻³), and rapid response time (≈2 s) at a low temperature (28 °C).

Conclusions:

• The developed OPNH shows superior mechanical and shape memory properties compared to conventional hydrogels.
• Its muscle-like working capacity, demonstrated by lifting 372 times its weight, highlights its potential for smart biomimetic muscles.
• This new class of shape memory material offers significant possibilities for advanced multistimulus responsive devices.