Covalent Integration of Benzimidazolium Acetate Units in Light-Induced 3D-Printable Acrylate-Based Vitrimers

The development of 3D printable acrylate-based vitrimers incorporating benzimidazolium acetate units acting as immobilized transesterification catalysts is reported. The catalytic activity of benzimidazolium acetates to promote transesterification reactions using molecular compounds is first demonstrated. Subsequently, polymer networks were synthesized via thermally-initiated free-radical copolymerization of 4-vinylbenzyl-ethyl-benzimidazolium acetate in combination with commercial mono- and bis-acrylates. Loading as low as 5 mol% was sufficient to activate transesterification exchange reactions within the polymer matrix, enabling reprocessability by compression molding. Photo-rheological properties of this vitrimer formulation were investigated, demonstrating its compatibility with Digital Light Processing (DLP) 3D printing toward the fabrication of high-resolution objects showing good surface fidelity and well-defined features. Notably, the covalent incorporation of benzimidazolium acetate salts does not interfere with the photopolymerization process. In addition, their catalytic activity toward transesterification reactions offers attractive end-of-life scenarios for the printed materials.