Oscillatory chemical reactions in the quest for rhythmic motion of smart materials

Isakova, Anna; Novakovic, Katarina

doi:10.1016/j.eurpolymj.2017.08.033

Cited by 34 publications

(23 citation statements)

References 84 publications

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“…1 Currently these reaction systems are generating profound interest in materials science as a driving force for smart materials, owing to the ability of smart materials to sense and react to changes in the environment, generated during the oscillatory process. 2 A number of self-oscillating materials and architectures have been reported, based on such reactions as the Landolt clock or Belousov-Zhabotinsky reaction. [3][4][5] The palladium-catalysed oxidative carbonylation (PCOC) reaction has recently attracted attention due to its ability to exhibit oscillations in pH, redox potential, turbidity and heat of reaction.…”

Section: Introductionmentioning

confidence: 99%

From small molecules to polymeric catalysts in the oscillatory carbonylation reaction: multiple effects of adding HI

Isakova

Murdoch

Novakovic

2018

Phys. Chem. Chem. Phys.

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The oscillatory palladium-catalysed carbonylation reaction opens new horizons for applications in smart materials due to the versatility of its conditions and substrates, as well as the adjustability of amplitude and period of pH oscillations. A variety of viable substrates have been demonstrated, including polymeric alkyne-terminated substrates. However, so far, there have not been any reports of polymer-based palladium catalysts in oscillatory mode. In this paper, we demonstrate pH oscillations in various systems, using commercially available palladium acetate, a triphenylphosphine palladium acetate complex and a polymer-bound palladium catalyst. While palladium acetate was able to generate oscillations under the conditions already established in our previous research on PdI2-catalysed oscillators, the other two catalysts needed the addition of HI to induce oscillations. HI forced an initial pH drop, bringing pH into the range where oscillations generally occur. Addition of HI had a significant effect on all catalysts, modifying the amplitude and period of oscillations, oscillation mode, as well as starting material conversion and product distribution.

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Section: Introductionmentioning

confidence: 99%

From small molecules to polymeric catalysts in the oscillatory carbonylation reaction: multiple effects of adding HI

Isakova

Murdoch

Novakovic

2018

Phys. Chem. Chem. Phys.

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“…The immobilization of enzymes in particles may provide insight into some of their observed behaviors. There is also increasing interest in coupling pH oscillators with pH sensitive materials for applications [18]. The dynamics predicted in simulations of urease-loaded particles, including oscillations, are yet to be obtained and the stability of the enzyme must be increased for such studies.…”

Section: Discussionmentioning

confidence: 99%

Kinetics of the urea–urease clock reaction with urease immobilized in hydrogel beads

Bubanja

Bánsági

Taylor

2017

Reac Kinet Mech Cat

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Feedback driven by enzyme catalyzed reactions occurs widely in biology and has been well characterized in single celled organisms such as yeast. There are still few examples of robust enzyme oscillators in vitro that might be used to study nonlinear dynamical behavior. One of the simplest is the urea-urease reaction that displays autocatalysis driven by the increase in pH accompanying the production of ammonia. A clock reaction was obtained from low to high pH in batch reactor and bistability and oscillations were reported in a continuous flow rector. However, the oscillations were found to be irreproducible and one contributing factor may be the lack of stability of the enzyme in solution at room temperature. Here, we investigated the effect of immobilizing urease in thiol-poly(ethylene glycol) acrylate (PEGDA) hydrogel beads, prepared using emulsion polymerization, on the ureaurease reaction. The resultant mm-sized beads were found to reproduce the pH clock and, under the conditions employed here, the stability of the enzyme was increased from hours to days.

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“…The oscillatory nature of changes in pH and reaction heat during the palladiumcatalyzed phenylacetylene oxidative carbonylation (PCPOC) reaction has opened this reaction up to new areas of study and possible applications [4,5]. One of the interesting observations made during previous investigations of the PCPOC reaction at temperatures from 0 to 40°C was the effect adding methanol to the reaction mixture had on the period and amplitude of the pH oscillations.…”

Section: Introductionmentioning

confidence: 97%

The effect of using a methanol–water solvent mixture on pH oscillations in the palladium-catalyzed phenylacetylene oxidative carbonylation reaction

Parker

Novakovic

2017

Reac Kinet Mech Cat

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The palladium-catalyzed phenylacetylene oxidative carbonylation reaction has been shown to produce regular oscillations in pH, reaction heat, and turbidity when conducted in batch with methanol as solvent. Previous studies of the catalytic system showed that water plays an important role in the behavior of the catalytic cycle. Investigating this role further, the reaction was performed in methanol-water mixtures. Experiments demonstrated that, under the conditions studied, oscillations in pH are feasible when the water concentration in the system is increased (0-30 V%). At the same time oscillations visually changed, being transformed from regular oscillations to more stepwise behavior as the proportion of water is increased. By establishing the relationship between the recorded pH and HI concentration it was found that increased water concentration suppresses HI formation and hence slows the autocatalysis in the reaction. It was also found that oscillations begin when the HI concentration is in the region of 1 9 10 -3 mol L -1 . Additionally, as the amount of water in the system increases a slight decrease in the concentration of HI when oscillations start was noted.

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Oscillatory chemical reactions in the quest for rhythmic motion of smart materials

Cited by 34 publications

References 84 publications

From small molecules to polymeric catalysts in the oscillatory carbonylation reaction: multiple effects of adding HI

From small molecules to polymeric catalysts in the oscillatory carbonylation reaction: multiple effects of adding HI

Kinetics of the urea–urease clock reaction with urease immobilized in hydrogel beads

The effect of using a methanol–water solvent mixture on pH oscillations in the palladium-catalyzed phenylacetylene oxidative carbonylation reaction

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