Sustainable Additive Manufacturing of Polyelectrolyte Photopolymer Complexes

Abstract Polyelectrolyte complexes (PECs), assemblies of oppositely charged polymers with powerful properties and wide‐ranging applications, are currently not melt‐processable via any conventional means and have been limited commercially to applications only as coatings. Herein, a unique strategy of pairing a polycation with an oppositely charged photopolymerizable monomer is employed. Vat photopolymerization of this mixture yields 3D spatial control over PECs for the first time. The properties of these 3D‐printed PECs are evaluated and are found to be similar to conventionally studied PEC materials. The water sensitivity of the PEC parts is adjustable through the incorporation of a small amount of a hydrophilic covalent crosslinker, highlighting potential future applications of these materials in 4D printing. Finally, the upcyclability of the additively manufactured PECs is demonstrated through the dissolution of a printed part and its incorporation into virgin resin to yield a part composed of partially recycled material. This chemistry has the potential to dramatically expand the application space of PEC materials and is a step towards a more circular economy for the field of additive manufacturing.