Additive manufacturing of highly entangled polymer networks

Area of Science:

• Materials Science
• Polymer Chemistry
• Additive Manufacturing

Background:

• Dense polymer chain entanglements enhance material stiffness and toughness.
• Achieving high entanglement density in vat photopolymerization additive manufacturing (e.g., digital light processing) is challenging.
• Current methods often require post-printing stimuli like heat or additional light exposure.

Purpose of the Study:

• To develop a facile strategy for creating highly entangled polymer networks during additive manufacturing.
• To enable the production of advanced hydrogels and elastomers with improved mechanical properties.
• To demonstrate a generalizable approach for high-resolution, multi-material 3D printing.

Main Methods:

• A novel approach combining light and dark polymerization stages within the printing process.
• Vat photopolymerization additive manufacturing (e.g., digital light processing) at room temperature.
• Characterization of monomer conversion, entanglement density, and mechanical properties (extension energies).

Main Results:

• Achieved high monomer conversion at room temperature without post-printing stimuli.
• Produced highly entangled hydrogels and elastomers with 4x to 7x higher extension energies compared to traditional digital light processing.
• Successfully printed high-resolution, multi-material structures with features like programmed adhesion to wet tissues.

Conclusions:

• The developed light and dark polymerization strategy effectively creates densely entangled polymer networks during additive manufacturing.
• This method significantly enhances the mechanical performance (stiffness, toughness, energy absorption) of 3D printed materials.
• The approach is generalizable for producing advanced functional materials and complex structures for various applications, including biomedical devices.