Autonomic composite hydrogels by reactive printing: materials and oscillatory response.

Soft Matter. 2014 Mar 7;10(9):1329-36.

Kramb RC, Buskohl PR, Slone C, Smith ML, Vaia RA.

AFRL/RX Materials & Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, USA. [email protected].

 

Abstract

 

Autonomic materials are those that automatically respond to a change in environmental conditions, such as temperature or chemical composition. While such materials hold incredible potential for a wide range of uses, their implementation is limited by the small number of fully-developed material systems. To broaden the number of available systems, we have developed a post-functionalization technique where a reactive Ru catalyst ink is printed onto a non-responsive polymer substrate. Using a succinimide-amine coupling reaction, patterns are printed onto co-polymer or biomacromolecular films containing primary amine functionality, such as polyacrylamide (PAAm) or poly-N-isopropyl acrylamide (PNIPAAm) copolymerized with poly-N-(3-Aminopropyl)methacrylamide (PAPMAAm). When the films are placed in the Belousov-Zhabotinsky (BZ) solution medium, the reaction takes place only inside the printed nodes. In comparison to alternative BZ systems, where Ru-containing monomers are copolymerized with base monomers, reactive printing provides facile tuning of a range of hydrogel compositions, as well as enabling the formation of mechanically robust composite monoliths. The autonomic response of the printed nodes is similar for all matrices in the BZ solution concentrations examined, where the period of oscillation decreases in response to increasing sodium bromate or nitric acid concentration. A temperature increase reduces the period of oscillations and temperature gradients are shown to function as pace-makers, dictating the direction of the autonomic response (chemical waves).

 

Go To Journal

 

Significance statement

Self-organization and synchrony are behaviors clearly demonstrated in living systems.  Fireflies blink in unison to coordinate mating calls, schools of fish swarm to evade and intimidate predators, and slime molds demonstrate advantageous collective behavior.  In each example, an assembly of complex, autonomous units developed order through the excitation and feedback of relatively rudimentary signals between near neighbors. Synchrony exists in synthetic systems too, such as electrons in an electrochemical potential or the assembly of chemically oscillating particles, suggesting that spontaneous organization could be encouraged through appropriate material design. Such composite materials provide a unique framework to perturb the dynamics of synchrony, and identify the key parameters to regulate autonomous networks. Furthermore, material synchrony and logic represent the next step in the evolution adaptive materials, and are critical building blocks for effective design of materials that sense and compute.

Composite, self-synching materials hold potential for a wide range of uses, however their implementation is limited by the small number of fully-developed systems. To increase the available systems, we have extended our prior work [1,2] by developing a post-functionalization technique where a reactive Ru catalyst ink is printed onto a non-responsive polymer substrate [3]. Using a succinimide–amine coupling reaction, patterns are printed onto co-polymer or biomacromolecular films containing primary amine functionality, such as polyacrylamide or poly-N-isopropyl acrylamide copolymerized with poly-N-(3 Aminopropyl)methacrylamide. When the films are placed in the Belousov–Zhabotinsky (BZ) solution medium, the oscillating reaction takes place only inside the printed nodes. In comparison to alternative systems, reactive printing provides facile tuning of a range of hydrogel compositions, as well as enabling the formation of mechanically robust composite monoliths. The precision of this reactive printing process enables the systematic investigation of shape, size, and composition effects on BZ chemical-mechanical feedback, which are critical to the design of synchronous materials.

  • “Autonomic Hydrogels through Postfunctionalization of Gelatin”, ML Smith, K Heitfeld, C Slone, RA Vaia Chemistry of Materials 24 (15), 3074-3080, 2012
  • “Designed Autonomic Motion in Heterogeneous Belousov–Zhabotinsky (BZ)-Gelatin Composites by Synchronicity “ Matthew L Smith, Connor Slone, Kevin Heitfeld, Richard A Vaia, Advanced Functional Materials 23 (22), 2835-2842, 2013
  • “Autonomic Composite Hydrogels by Reactive Printing: Materials and Oscillatory Response” RC Kramb, PR Buskohl, C Slone, ML Smith, RA Vaia, Soft matter 10 (9), 1329-1336, 2014

 

Autonomic composite hydrogels by reactive printing materials and oscillatory response

Check Also

Advancing Fusion Energy: High-Field REBCO Superconducting Magnets in the SPARC TFMC Program - Advances in Engineering

Advancing Fusion Energy: High-Field REBCO Superconducting Magnets in the SPARC TFMC Program