Direct-Ink-Writing Printing of Shape Memory Cross-Linked Networks from Biomass-Derived Small Molecules

The rapid development of 3D printing, also known as additive manufacturing, has opened up new opportunities for applying shape memory polymers (SMPs) in various fields. The use of abundant, inexpensive, and easily accessible biomass materials as printing raw materials not only facilitates the creation of more intricate SMPs but also aligns with the principles of low-carbon, green, and sustainable development. Here, we successfully printed a shape memory cross-linked network (NW-MO-TTMP) in a single step by direct-ink-writing printing and an in-situ thiol-ene click reaction with magnolol and trimethylolpropane tris(3-mercaptopropionate) as raw materials. The resulting NW-MO-TTMP network exhibited high mechanical properties and a tensile strength (σ) of up to 2.7 MPa when the thiol-ene ratio was 1.0:1, and the photo-initiator content was 1.5%. To improve printability, ethyl cellulose (EC) derived from biomass was incorporated to enhance the viscosity of the printing precursor fluid, resulting in a significant increase in the σ of the NW-MO-TTMP/EC network, reaching 20.6 MPa. Moreover, the successful printing of intricate models, such as the ‘whale’ and ‘octopus,’ demonstrated excellent shape memory effects. This approach highlights the potential of combining biomass-derived materials with advanced 3D printing techniques to develop sustainable and high-performance SMPs.