Multifunctional dithiolane monomers for multi-scale, recyclable light-driven additive manufacturing

Area of Science:

• Materials Science
• Polymer Chemistry
• Additive Manufacturing

Background:

• Photopolymerization is crucial for additive manufacturing, enabling precise 3D object creation.
• Developing recyclable resins with tunable properties is essential for sustainable manufacturing.

Purpose of the Study:

• To synthesize and characterize a novel tetrafunctional monomer for light-based additive manufacturing.
• To investigate the photopolymerization behavior and recyclability of the developed monomer.
• To demonstrate high-resolution 3D printing capabilities using the new material.

Main Methods:

• Synthesis of lipoic acid pentaerythritol ethoxylate, a tetrafunctional monomer with 1,2-dithiolane groups.
• Photopolymerization studies in the presence and absence of photoinitiators.
• Additive manufacturing using dynamic light processing and two-photon lithography.
• Recycling of the polymerized network back to the monomer via heating and solvent dilution.

Main Results:

• The tetrafunctional monomer successfully underwent photopolymerization, forming covalent adaptable networks with linear disulfides.
• High-resolution 3D parts were printed, with feature sizes down to 1 μm, across scales from cm to μm.
• The polymerized network was recycled with approximately 95% monomer recovery.
• Repolymerization of the recovered monomer yielded nearly identical modulus evolution compared to the initial polymerization.

Conclusions:

• A novel tetrafunctional dithiolane monomer was successfully developed for additive manufacturing.
• The monomer enables photopolymerization with or without exogenous photoinitiators, offering versatility.
• The resulting covalent adaptable networks are recyclable, demonstrating a sustainable approach to 3D printing resins.
• This work advances the field of recyclable resins and multifunctional monomers for high-resolution additive manufacturing.