Shape- and size-dependent patterns in self-oscillating polymer gels

Chen, Irene Chou; Kuksenok, Olga; Yashin, Victor V.; Moslin, Ryan M.; Balazs, Anna C.; Vliet, Krystyn J. Van

doi:10.1039/c0sm01007c

Cited by 65 publications

(121 citation statements)

References 33 publications

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“…For example, in agreement with the experiments, we observed the in-phase synchronization of the chemical and mechanical oscillations for relatively small sized samples (19,20) and the decrease of the oscillation period with an increase in the concentration of malonic acid (12,19). Additionally, the shape-and size-dependent pattern formation observed in our gLSM simulations showed qualitative agreement with experimental studies (21). Our simulations were also useful in explaining how gradients in cross-link density could drive long, thin BZ gels to both oscillate and bend, and thereby undergo concerted motion (22).…”

supporting

confidence: 79%

“…Notably, millimeter-sized pieces of the BZ gels can actually undergo self-oscillations for a few hours without replenishment of reagents (14,15). Moreover, recent experiments demonstrated that upon depletion of reagents the system can be readily "refueled" by replenishing these solutes (21). The scenarios involving the rectangular samples also reveal that the self-generated distributions of activator can be tailored by simply altering the shape of the gel.…”

mentioning

confidence: 94%

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Reconfigurable assemblies of active, autochemotactic gels

Dayal

Kuksenok

Balazs

2012

Proc. Natl. Acad. Sci. U.S.A.

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Using computational modeling, we show that self-oscillating Belousov-Zhabotinsky (BZ) gels can both emit and sense a chemical signal and thus drive neighboring gel pieces to spontaneously self-aggregate, so that the system exhibits autochemotaxis. To the best of our knowledge, this is the closest system to the ultimate selfrecombining material, which can be divided into separated parts and the parts move autonomously to assemble into a structure resembling the original, uncut sample. We also show that the gels' coordinated motion can be controlled by light, allowing us to achieve selective self-aggregation and control over the shape of the gel aggregates. By exposing the BZ gels to specific patterns of light and dark, we design a BZ gel "train" that leads the movement of its "cargo." Our findings pave the way for creating reconfigurable materials from self-propelled elements, which autonomously communicate with neighboring units and thereby actively participate in constructing the final structure.self-oscillating gels | autochemotactic gels | autochemotactic self-organization S pecies ranging from single-cell organisms to social insects can undergo autochemotaxis, where the entities move toward a chemo-attractant that they themselves emit. This mode of signaling allows the organisms to form large-scale structures, with amoebas (1) and Escherichia coli (2) self-organizing into extensive multicellular clusters and termites constructing macroscopic mounds (3). Notably there are few equivalents of such autochemotactic-driven assembly in the synthetic world. Although researchers have devised a range of nano-and microscopic selfpropelled particles (4), hardly any exhibit autochemotaxis (5) that leads to the formation of extended structures (6). Although recent theoretical models provide insight into the autochemotaxis of a self-propelled walker (7) and active Brownian particles (8), these studies provide few guidelines for synthesizing specific materials that display autochemotactic self-organization. The latter materials would open new routes for dynamic, reconfigurable self-assembly, where self-propelled elements communicate with neighboring units and thereby actively participate in constructing the final structure. Herein, we use computational modeling to show that millimeter-sized polymer gels can display such self-sustained, autochemotatic behavior. In particular, we demonstrate that gels undergoing the self-oscillating Belousov-Zhabotinsky (BZ) reaction (9) not only respond to a chemical signal from the surrounding solution, but also emit this signal and thus, multiple neighboring gel pieces can spontaneously self-aggregate into macroscopic objects. These findings indicate that BZ gels can undergo a form of "selfrecombining": if a BZ gel is cut into distinct pieces and the pieces are moved relatively far apart, then their autochemotactic behavior drives the parts to move autonomously and recombine into a structure resembling the original, uncut sample (Fig. 1). We also show that the gels' coordinated motion can ...

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supporting

confidence: 79%

mentioning

confidence: 94%

Reconfigurable assemblies of active, autochemotactic gels

Dayal

Kuksenok

Balazs

2012

Proc. Natl. Acad. Sci. U.S.A.

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“…5,49 Additionally, the shape-and size-dependent pattern formation observed in these gLSM simulations showed qualitative agreement with experimental studies. 20 Such simulations were also useful in explaining how gradients in crosslink density could drive long, thin BZ gels to both oscillate and bend, and thereby undergo concerted motion. 53 Recently, we modified the gLSM approach to model patches of BZ gels that are embedded within a neutral, non-responsive gel and through this model, could successfully capture the synchronization between circular BZ gel patches 54 that encompassed different concentrations of Ru catalyst.…”

Section: Dynamics Of the Bz Gelsmentioning

confidence: 99%

“…In fact, millimeter sized pieces of the BZ gels can pulsate autonomously for hours. 18,19 Moreover, these gels can be ''recycled'' by simply replenishing the consumed solutes, as demonstrated by Chen and Van Vliet et al 20 In the latter study, the researchers showed 20 that recycled samples displayed the same pattern formation and period of oscillation as freshly prepared gels.…”

Section: Introductionmentioning

confidence: 96%

Chemo-responsive, self-oscillating gels that undergo biomimetic communication

et al. 2013

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Species ranging from single-cell organisms to social insects can undergo auto-chemotaxis, where the entities move towards a chemo-attractant that they themselves emit. Polymer gels undergoing the self-oscillating Belousov-Zhabotinsky (BZ) reaction exhibit autonomous, periodic pulsations, which produce chemical species collectively referred to as the activator. The diffusion of this activator into the surrounding solution affects the dynamic behavior of neighboring BZ gels and hence, the BZ gels not only emit, but also respond to self-generated chemical gradients. This review describes recent experimental and computational studies that reveal how this biomimetic behavior effectively allows neighboring BZ gels to undergo cooperative, self-propelled motion. These distinctive properties of the BZ gels provide a route for creating reconfigurable materials that autonomously communicate with neighboring units and thereby actively participate in constructing the desired structures.

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“…Ru(vbpy), however, is difficult to synthesize from Ru(bpy) 3,8,10 costly to purchase from suppliers and, depending on the counter ion, has limited solubility in water and alcohols, which are the most common solvents for hydrogel polymerization reactions. Ru(bpy) 2 (4-methyacryloylmethyl-4'-methylbpy) [Ru(mbpy)], another BZ gel catalyst, requires numerous reaction and column purification steps, also limiting its broad utility.…”

Section: Introductionmentioning

confidence: 99%

Belousov–Zhabotinsky Hydrogels: Relationship between Hydrogel Structure and Mechanical Response

et al. 2015

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The novel chemo-mechanical feedback within autonomic Belousov-Zhabotinsky (BZ) hydrogels mimics the complex adaptivity found in natural systems, and inspires soft device concepts for chemical computing, sensing and actuation. A quantitative relationship between the dynamic response, strain, BZ reagents and hydrogel constituents however, is still evolving due to a limited material suite. Using a modular synthesis strategy for free-radical BZ-catalyst monomers, we compare the impact of cross-linker, catalyst, and total polymer concentration on the cyclic strain of PNIPAm and PAAm based BZ hydrogels. The oscillator strain of the hydrogel in the BZ solution relative to the difference between equilibrium swelling of the fully oxidized and reduced states highlights the trade-off between BZ reaction kinetics, hydrogel elasticity, and catalyst concentration. For a PNIPAm-based BZ gel, a maximum strain of 20% occurs at a total polymer and [Ru] concentration of 4.8 ± 0.5 μg/mm 3 and 1.5 mM due to a complementary balance of Ru content, extended BZ period (33 ± 8 min), and modest network crosslinking. The modular synthesis approach enables formulation studies to identify the BZ hydrogel architecture that provides maximum strain response and robustness, as well as elucidating the interrelationship between hydrogel structure, composition and reaction conditions.

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Shape- and size-dependent patterns in self-oscillating polymer gels

Cited by 65 publications

References 33 publications

Reconfigurable assemblies of active, autochemotactic gels

Reconfigurable assemblies of active, autochemotactic gels

Chemo-responsive, self-oscillating gels that undergo biomimetic communication

Belousov–Zhabotinsky Hydrogels: Relationship between Hydrogel Structure and Mechanical Response

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