3D Printing of a Thermo‐ and Solvatochromic Composite Material Based on a Cu(II)–Thymine Coordination Polymer with Moisture Sensing Capabilities

Abstract

This work presents the fabrication of 3D printed composite objects based on copper(II) one-dimensional coordination polymer (CP1) decorated with thymine along its chains with potential utility as an environmental humidity sensor and as a water sensor in organic solvents. This new composite object has a remarkable sensitivity, ranging from 0.3 to 4% of water in organic solvents. The sensing capacity is related to the structural transformation due to the loss of water molecules that CP1 undergoes with temperature or by solvent molecules competition, which induces significant change in color simultaneously. The CP1 and 3D printed materials are stable in air over one year and also at biological pHs (5-7), therefore suggesting potential applications as robust colorimetric sensor. These results open the door to generate a family of new 3D printed materials based on the integration of multifunctional coordination polymers with organic polymers.

New Promises and Opportunities in 3D Printable Inks Based on Coordination Compounds for the Creation of Objects with Multiple Applications

“…Thus, intelligent CPs, without practical utility, if synthesized as colloids or polycrystals, can be printed as sensors with different morphologies. This is the case of 1D Cu II CP and thymine, [22] which changes color with humidity (from blue to violet). Its easy preparation as colloidal nanofibers enabled its formulation as a 3D printed ink.…”

“…For example, DLP was used to fabricate a composite based on a copper(II) 1D coordination polymer (CP) decorated with thymine residues. The stimuli‐responsive CP was embedded in an organic matrix, and the 3D printed objects can be used as robust and simple humidity sensors [22] …”

“…recently fabricated a water sensor based on a nonporous copper(II) 1D CP grafted with modified thymine as a terminal ligand and 4,4′‐bipyridine as a bridging ligand between the metal centers (Figure 13 a). [22, 50] The structure also contains one water molecule coordinated to the Cu II metal center and two other solvation water molecules.…”

Control-Based 4D Printing: Adaptive 4D-Printed Systems

“…Functional polymers, due to their variable mechanical and electrical response to external stimuli such as humidity, temperature, pH and stress, are often used in 4D printing. In an adaptive 4D-printed system, sensing can be done in spatial layers using integrated sensors [88]. Electrically conductive extrudates, which contain conductive nano particles, have frequently been used in capacitive-based sensor 3D printing for measuring humidity and temperature [89].…”

Hierarchical ordering in light-triggered additive manufacturing

“…The same group used [Cu(TAcO) 2 (H 2 O)(4,4′-bipy)] n •2H 2 O, a 1D metal-organic coordination polymer, together with dipropylene glycol diacrylate and diethylene glycol methyl ether, to fabricate, by DLP, 3D-printed structures capable of moisture sensing. 200 Effectively, the reversible substitution of the water ligand by a solvent molecule leaded to a colour change from blue to purple after substitution. The original being recovered after several minutes when exposed to ambient atmosphere.…”