Recyclable, Biobased Photoresins for 3D Printing Through Dynamic Imine Exchange

Abstract

Transimination reactions are highly effective dynamic covalent reactions to enable reprocessability in thermosets, as they can undergo exchange without the need for catalysts, by exposing the materials to external stimuli such as heat. In this work, a series of five biobased vanillin-derived resin formulations consisting of vanillin acrylate with vanillin methacrylate-functionalized Jeffamines were synthesized and 3D-printed using digital light projection (DLP). The resulting thermosets displayed a range of mechanical properties (Young’s modulus 2.05–332 MPa), which allow for an array of applications. The materials we obtained have self-healing abilities, which were characterized by scratch healing tests. Additionally, dynamic transimination reactions enable these thermosets to be reprocessed when thermally treated above their glass transition temperatures under high pressures using a hot press. Due to the simple synthetic procedures and the readily available commercial Jeffamines, these materials will aid in promoting a shift to materials with predominantly biobased content and help drift away from polymers made from non-renewable resources.

Advanced supramolecular design for direct ink writing of soft materials

“…26 Dynamic covalent chemistry has been introduced to FDM filaments, generating products with better isotropic performance. [27][28][29] A variety of polymer designs have been introduced for DIW, producing a plethora of new materials with stimuli-responsiveness, 30,31 outstanding mechanical properties, 32 biocompatibility, 33,34 and optical/electronic properties. 35,36 DIW and vat-polymerization-based 3D-printers are widely used for soft materials AM (Fig.…”

Lignin-Based Covalent Adaptable Network Resins for Digital Light Projection 3D Printing

“…Vanillin has grown to become a popular material for bio-based polymers, because of its versatility. 13,14 Soybean oil is another abundant and low-cost bio-based resource with over 50 million tons produced annually. 13,15 Acrylated epoxidized soybean oil (AESO) can be used as a UV curable coating, however it is often blended with petroleum-based monomers due to its limitations with thermal and mechanical properties and poor flowability.…”

“…The dynamic linkages are used in conjunction with permanent crosslinks to create materials that retain their shape while self-healing. 14,34,35 The use of DCC in thermosets helps retain the mechanical properties of the networks while gaining the reprocessable properties of a thermoplastic polymer. 14,36 Here we report a series of bio-based and 3D printable CANs that can undergo dynamic transesterification.…”

“…14,34,35 The use of DCC in thermosets helps retain the mechanical properties of the networks while gaining the reprocessable properties of a thermoplastic polymer. 14,36 Here we report a series of bio-based and 3D printable CANs that can undergo dynamic transesterification. The resins consist of bio-based lignin, vanillin, and soybean oil monomers, and are cured through a thiolacrylate radical polymerization which is compatible with the 3D printer light source.…”

Impact of Torsional and Conformational Flexibility on Pedal Motion and Thermal Expansion in Pyridyl Bisimine Cocrystals

“…In Schiff-base compounds, imines frequently undergo enol-keto tautomerism, which depends on molecular motion ability, proton transfer, and overall crystal packing. − Imines also exhibit torsional flexibility and often crystallize in nonplanar geometries, which impacts extended crystal packing. , We recently investigated the solid-state properties of molecules containing one imine group and showed that the torsional flexibility affords unique TE properties . Imine-based molecules have frequently been used as ligands in metal–organic frameworks , and as components within covalent-organic frameworks; − however, cocrystals containing imines are less explored . Thus, we were motivated to design and synthesize hydrogen-bonded cocrystals featuring imine functional groups, with the goal of investigating torsional flexibility, dynamic pedal motion, and impacts on TE properties.…”