# Self‐Healing Behavior of Metallopolymers in Complex3D‐Structures Obtained by DLP‐Based 3D‐Printing

## TL;DR

This paper explores how metallopolymers printed using DLP 3D printing can self-heal mechanical damage with high efficiency while maintaining their 3D structure.

## Contribution

The study introduces DLP-based 3D-printed metallopolymers with self-healing properties and reveals new structure-property relationships.

## Key findings

- Metallopolymers healed mechanical damage with up to 97% efficiency without losing structural integrity.
- Self-healing occurred at 70 °C or 120 °C within 24 hours after damage introduction.
- The study identified molecular structure dependencies influencing the self-healing behavior.

## Abstract

This current study focusses on the investigation of the self‐healing abilities of metallopolymers containing different kinds of metal complexes, which were processed by direct digital light processing (DLP) based three‐dimensional (3D) printing. For this purpose, 2‐phenoxyethyl acrylate is mixed with ligand‐containing monomers either based on triphenylmethyl(trt)‐histidine or terpyridine, respectively. Either zinc(II) or nickel(II) salts are successfully applied for a complexation of the ligand monomers in solution and, subsequently, photopolymerization is performed. The thermo‐mechanical properties of the obtained metallopolymers were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) as well as dynamic mechanical thermal analysis (DMTA). Multiple damages with defined forces ranging from 20 to 1500 mN were introduced into the 3D‐structures and successfully healed within 24 h at 70 °C or 120 °C, respectively without losing the structural integrity of the overall 3D‐structures. Herein, excellent healing efficiencies up to 97 % were determined. Consequently, these hollow structures not only feature very good self‐healing abilities but also excellent retention of the 3D‐structure at and above the healing temperature.

This study presents the digital light processing (DLP) based three‐dimensional (3D) printing of metallopolymers featuring self‐healing abilities. The obtained structures were able to heal mechanical damage with excellent efficiencies up to 97 % without losing their 3D‐structure. Additionally, the healing behavior in dependency of the molecular structure was analyzed in detail revealing new structure‐property‐relationships.