Three-Dimensional Shape Transformation of Eu³⁺-Containing Polymer Films through Modulating Dynamic Eu³⁺-Iminodiacetate Coordination

Abstract

Shape-transformative materials that can autonomously adopt three-dimensional (3D) shapes in response to environmental stimuli are of interest for the development of sensors and soft robotics. We herein report a new synthetic strategy to fabricate shape-transformable Eu3+-containing interpenetrating polymer films consisting of poly­(vinyl alcohol) (PVA) and poly­(3-iminodiacetate-2-hydroxypropylmethacrylate-co-acrylic acid) (P­(IDHPMA-co-AA)). Given the dynamic nature of Eu3+-iminodiacetate (IDA) coordination, ink patterning and water/Fe3+ diffusion are used to generate the in-plane or z-directional heterogeneities of Eu-IDA dynamic coordination in the polymer film, respectively. The heterogeneities can be visualized by the distribution of fluorescence emission of Eu3+. When subjected to high humidity, the differences in the swelling ratio and modulus as a result of chemical inhomogeneity further drive various 3D shape morphings, including rolling, helixing, twisting, surface buckling, and folding. Shape transformation is reversible upon the removal of moisture from the polymer films. The ink concentration and environmental humidity are demonstrated to impact the shape transformation kinetics and the final 3D shape along with other geometric parameters. Our work illustrates a novel way to fabricate new-generation biomimetic actuators and sensors.

Modular Synthesis and Patterning of High-Stiffness Networks by Postpolymerization Functionalization with Iron–Catechol Complexes

“…This ability to prepare gradient Fe 3+ –catechol network structures also opens up the possibility of controlling the patterning of Fe 3+ –catechol domains in the X - and Y -directions. Soft lithography solution masking techniques coupled with controlled Fe 3+ diffusion allow 3D network films to be prepared with a diversity of hard (Fe 3+ –catechol) and soft (catechol only) network patterns. ,, To illustrate the utility of this strategy, swollen networks were covered with a PDMS mask that preferentially exposed distinct regions of the network surface to Fe 3+ via a reservoir of buffered Fe­(NO 3 ) 3 solution (Figure a). As iron diffusion is relatively slow in networks with high catechol grafting densities, this approach allows for control of feature sizes at resolutions of ∼700 μm (cf., QR code in Figure b).…”

“…Building on this success, there is significant opportunity for extending this design concept to a more modular synthetic strategy based on initial rapid and orthogonal free radical cross-linking followed by secondary functionalization with readily available catechol derivatives such as dopamine, alleviating the requirement for protection/deprotection of catechol moieties , (Figure ). The versatility of radical cross-linking systems and the wide availability of starting materials would also enable the preparation of patterned materials for soft robotics, , tissue engineering scaffolds, and high-strength, functional 3D printed materials …”

Dual Encryption in a Shape Memory Hydrogel with Rewritable Fluorescent Information

“…The mechanism of fluorescence quenching was competitive coordination of Cu 2+ and Eu 3+ to APA. [38,39] Once information www.advmattechnol.de was printed on the hydrogel by the ink, Cu 2+ diffused into the hydrogel and displaced Eu 3+ as the central ion coordinating with ligand APA. Since Cu-APA did not display fluorescence under 254 nm irradiation (Figure S7, Supporting Information), the fluorescence quenching of the patterned area was visible to naked eyes.…”

Strain sensing multi-stimuli responsive light emitting lanthanide-based tough and stretchable hydrogels with tunable luminescence and fast self-recovery using metal–ligand and hydrophobic interactions

“…25 Exploiting this dynamic Eu-iminodiacetate coordination, Yin et al reported a stimuli responsive shape transformation in polymer films consisting of polyvinyl alcohol (PVA) and poly (3-iminodiacetate-2-hydroxypropylmethacrylate- co -acrylic acid) (P-(IDHPMA- co -AA). 26 He and co-workers reported an Eu-DPA (dipicolylamine) containing random copolymer based film of poly( n -butyl acrylate- co -2-hydroxy-3-dipicolylamino methacrylate) (P( n BA- co -GMADPA)) which was responsive towards moisture. 27 Similarly, Holten-Andersen and co-workers proposed a strategy to obtain white light emitting hydrogels by tuning the concentration of carbon dots (for blue light emission), Eu 3+ and Tb 3+ ions in a polyacrylamide/polyacrylic acid gel network.…”