3D printing of shape memory hydrogels with tunable mechanical properties

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomedical Engineering

Background:

• Soft materials like hydrogels are crucial for applications in soft robotics and require adaptable manufacturing and design.
• Existing methods often limit the freedom and complexity of hydrogel fabrication.

Purpose of the Study:

• To develop robust, thermoresponsive shape memory gels (SMGs) with tunable properties using 3D printing.
• To explore the potential of these SMGs in various fields including robotics, biomedicine, and optics.

Main Methods:

• Utilized a customized optical 3D gel printer for rapid, moldless fabrication of poly(dimethyl acrylamide-co-stearyl acrylate and/or lauryl acrylate) (PDMAAm-co-SA and/or LA) based SMGs.
• Varied monomer compositions to tune mechanical, thermal, optical, and swelling properties.
• Characterized SMGs using thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC).

Main Results:

• Achieved excellent fixity and recovery ratios in printed SMGs.
• Demonstrated a wide range of tunable Young's modulus (0.04-17.35 MPa) and strain (612-2363%).
• Observed tunable transition temperatures (29-49.5 °C) and high transparency with refractive indices suitable for optical applications.

Conclusions:

• 3D printed SMGs offer high robustness, free formability, and tunable properties.
• These advanced hydrogels show significant potential for diverse applications in biomedicine, robotics, and sensing.