Redox-Responsive Gel−Sol/Sol−Gel Transition in Poly(acrylic acid) Aqueous Solution Containing Fe(III) Ions Switched by Light

Peng, Fei; Li, Guangzhao; Liu, Xinxing; Wu, Shuizhu; Tong, Zhen

doi:10.1021/ja807087z

Cited by 250 publications

(193 citation statements)

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“…Within this context supramolecular low molecular weight gelators (LMWG), with their reversible and dynamic intermolecular interactions are achieving increasing prominence [10][11][12][13][14][15] . Work on switchable gels includes 2 systems involving photo-, pH, and redox based switching, ultrasound induced gelation, and switchable catalysis [16][17][18][19][20][21][22][23] . In order to systematically develop smart materials with controllable and well understood changes in bulk properties, an understanding of the intermolecular interactions in the system and the way in which they engage in hierarchical self-assembly in order to produce emergent morphologies with complex behavior is required.…”

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confidence: 99%

Halogen-bonding-triggered supramolecular gel formation

et al. 2012

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Tunable gel phase materials with novel properties such as switchable rheology and controlled flow characteristics are an emerging topic of interest in potential applications as diverse as pharmaceutical crystallization, catalysis, drug delivery and controlled release, wound healing, and stabilization of drilling mud [1][2][3][4][5][6][7][8][9] . Within this context supramolecular low molecular weight gelators (LMWG), with their reversible and dynamic intermolecular interactions are achieving increasing prominence [10][11][12][13][14][15] . Work on switchable gels includes 2 systems involving photo-, pH, and redox based switching, ultrasound induced gelation, and switchable catalysis [16][17][18][19][20][21][22][23] . In order to systematically develop smart materials with controllable and well understood changes in bulk properties, an understanding of the intermolecular interactions in the system and the way in which they engage in hierarchical self-assembly in order to produce emergent morphologies with complex behavior is required. The link between even primary supramolecular interactions and bulk material properties is often unclear, however. Recent work has highlighted some simple approaches to controllable or smart materials that have met with considerable success. A key theme in particular is setting up a 'tipping point' in a system comprising competing intermolecular interactions which contribute to either gel assembly or gel dissolution. In this way a number of research groups have shown that anion binding in competition with urea self-assembly can be used to 'turn-down' and ultimately 'turn-off' gelation behavior 24,25 . Interestingly, in alternative systems, anion binding has also been used to induce gelation 26,27 . In a similar way metal coordination has also been used to tune gel properties 25 . In a series of bis(urea) gels we have shown how a combination of metal-and anion-binding can allow comprehensive control over the system. Competitive anion binding reduces gel strength by inhibiting urea -tape hydrogen-bond formation [28][29][30][31] .Conversely, metal coordination in pyridyl-urea compounds results in metal binding to the pyridyl group which suppresses the alternative, gel-inhibiting urea-pyridyl hydrogenbonding interaction, freeing the urea groups to form fibrils, and hence gels, as a result of the urea tape hydrogen-bonding motif [32][33][34] . These competitive interaction modes are summarised in Figure 1. 3

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confidence: 99%

Halogen-bonding-triggered supramolecular gel formation

et al. 2012

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“…49 Since the Fe 3+ -carboxyl complexation is redoxsensitive, the hydrogel also exhibits ascorbic acid-responsive shape memory behaviour. After immersion in FeCl 3 solution, the carboxyl groups in the hydrogel can form complexation with Fe 3+ ions, introducing additional cross-linking into the hydrogel, which will act as switchable points for the ascorbic acid-responsive shape memory performance.…”

Section: Ascorbic Acid-responsive Shape Memory Performancementioning

confidence: 99%

Tough polypseudorotaxane supramolecular hydrogels with dual-responsive shape memory properties

et al. 2016

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“…Their use as actuation materials and structures for biomedical and soft-robotics applications has been widely studied recently; with the desired actuation pathway often being created by inhomogeneity to the material or structure either during construction or synthesis, or as presented here, programmed into the material post construction or synthesis [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Novel Multi-Stage Three-Dimensional Deployment Employing Ionoprinting of Hydrogel Actuators

Baker¹,

Wass

Trask³

2016

MRS Advances

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Novel multi-stage adaptive morphing of a hydrogel cube has been achieved by combining multi-metal ionoprinting and redox chemistry of iron. A demonstration of the two-stage deployment has been shown for (1) the selective opening and closing of the cube’s lid, where the hinge point has been ionoprinted with iron, and (2) the full unfolding and folding of the cube into its cruciform net, with remaining hinges ionoprinted with vanadium. The selective unfolding and folding is achieved by alternating the oxidation state of iron between +2 and +3. This is achieved using redox chemistry selective for iron. This approach could be applied, in principle, to more degrees of staging by adding additional redox responsive ionoprinted cations and appropriate selection of reducing agents.

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Redox-Responsive Gel−Sol/Sol−Gel Transition in Poly(acrylic acid) Aqueous Solution Containing Fe(III) Ions Switched by Light

Cited by 250 publications

References 19 publications

Halogen-bonding-triggered supramolecular gel formation

Halogen-bonding-triggered supramolecular gel formation

Tough polypseudorotaxane supramolecular hydrogels with dual-responsive shape memory properties

Novel Multi-Stage Three-Dimensional Deployment Employing Ionoprinting of Hydrogel Actuators

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