Direct DLP-based 3D-printing of metallopolymers featuring shape-memory abilities

This study presents for the first time the direct digital light processing (DLP) based three-dimen­sional (3D) printing of metallopolymers featuring different kinds of metal complexes. 2-Phenoxyethyl acrylate and ligand-containing monomers based on terpyridine, and triphenylmethyl(trt)-histidine are utilised. After successful complexation of zinc(II) and nickel(II) salts, respectively, within the monomer mixture the polymerisation via photo-induced printing is performed. The hereby obtained smart materials can be printed in any form ranging from simple rectangular rods to complex hollow structures. Inductively coupled plasma optical emission spectroscopy (ICP-OES) and Fourier-transform (FT) Raman spectroscopy reveal the successful imbedding and implementation into the polymeric structure. Additionally, an imaging across the 3D-printed structure could be performed indicating the equal distribution of the complexes in the structure. Furthermore, the 3D-printed specimens feature excellent shape-memory behaviour. Thermo-mechanical analysis (TMA) reveals fixity rates after mechanical deformation up to 100% and recovery rates up to 99%.