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Chemically Fueled Dissipative Assembly and Metal−Ligand Coordination
Presented by Sophia Costantino
Introduction
Introduction
Welcome! This site showcases our work on dynamic polymer hydrogels that use chemical fuels and metal–ligand coordination to control mechanical properties. Our materials exhibit tunable stiffness, self-healing, and reversible network behavior—offering applications in smart materials, tissue engineering, and soft robotics.
By introducing temporary anhydride crosslinks through chemical fuels and stabilizing interactions with metal–ligand bonds, we can shift hydrogels in and out of mechanical states. Our research compares ligand structures and fuel concentrations to understand how network dynamics can be precisely tuned.
Polymer Synthesis
Polymer Synthesis
Scheme a) We synthesized polymers via RAFT polymerization, using acrylic acid, acrylamide, and para-substituted DPA-based ligands. N,N′-methylenebisacrylamide (MBAm) was used to introduce permanent covalent crosslinking between polymer chains.
Scheme b) Upon the introduction of the chemical fuel EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide), temporary anhydride crosslinks are formed between carboxylic acid groups. These transient bonds increase network strength and stiffness but hydrolyze over time, returning the material to its original equilibrium state.
Mechanical Properties and Fuel-Driven Dynamics
Mechanical Properties and Fuel-Driven Dynamics
We used frequency and time sweep rheology to evaluate how polymer composition, metal–ligand coordination, and chemical fuel affect mechanical behavior.
Fe²⁺ vs Ni²⁺ Hydrogels
MeO-DPA–based hydrogels exhibited the highest storage modulus (G′) with Fe²⁺, indicating stronger binding interactions. Cl-DPA showed the lowest G′ across frequencies. Hydrogels incorporating Ni²⁺ displayed generally lower moduli, suggesting weaker coordination compared to Fe²⁺ systems.
EDC-Fueled Dynamic Crosslinking:
Time sweeps after EDC addition demonstrated transient increases in G′ due to the formation of anhydride crosslinks. Once EDC was consumed, hydrolysis restored the polymer to its initial mechanical state. Chain length did not significantly impact the maximum G′, but higher EDC concentration led to stronger transient stiffness.
Self-Healing and Transient Behavior
Self-Healing and Transient Behavior
We tested the reversibility and spatial control of the polymer networks using adhesion, self-healing, and patterning experiments. When EDC was introduced between carboxylic acid–functionalized gels, adhesion increased due to temporary crosslink formation. Upon depletion of the fuel, the materials could be separated or reshaped—demonstrating the transient and tunable nature of the network.
Conclusion & Future Work
Conclusion & Future Work
By integrating chemically fueled and metal–ligand crosslinking, we designed responsive hydrogels with tunable and reversible mechanical properties. Our system allows control over stiffness, healing, and material dynamics through ligand selection and fuel concentration.
Future Directions:
Evaluate additional metal ions (e.g., Zn²⁺, Cu²⁺)
Optimize for biocompatibility and tissue scaffold applications
Test mechanical behavior under physiological conditions
Integrate with responsive imaging or stimulus-triggered release
Acknowledgements
Acknowledgements
Team Members:
Chamoni Rajawasam
Sophia Costantino
Corvo Tran
Rob Ross-Shannon
Kathleen McCoy
Obed Dodo
Jessica Sparks
C. Scott Hartley
Dominik Konkolewicz
Acknowledgement:
This project was funded by the U.S. Department of Energy under Award No. DE-SC0018645.
🏛️ Department of Chemistry and Biochemistry, Miami University
📍 Oxford, Ohio 45056
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