Reorganization of hydrogen bond network makes strong polyelectrolyte brushes pH-responsive

Wu, Bo; Wang, Xiaowen; Yang, Jun; Hua, Zan; Tian, Ke; Kou, Ran; Zhang, Jian; Ye, Shuji; Luo, Yi; Craig, Vincent S. J.; Zhang, Guangzhao; Liu, Guangming

doi:10.1126/sciadv.1600579

Cited by 50 publications

(113 citation statements)

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“…In Figure , the dissipation shift (ΔD) of the PMETAC brushes also exhibits distinct changes with the salt concentration in the presence of different types of counterions. ΔD is generally related to the conformation of the polymer brushes and the friction between the polymer brushes and the surrounding water molecules ,,. In the presence of ClO 4 − , ΔD sharply decreases as the salt concentration increases from 0 to 5×10 −5 M, and then gradually decreases with the increase in salt concentration from 5×10 −5 to 5×10 −3 M. As the salt concentration increases further from 5×10 −3 to 0.5 M, no obvious changes in ΔD are observed.…”

Section: Resultsmentioning

confidence: 99%

“…It is worth noting that the four types of counterions empolyed in this study are not the hydrogen bond donors. Thus, unlike the hydronium and hydroxide which are hydrogen bond donors, the variation of concentration of the counterions would not have obvious influences on the hydrogen bonding interactions between the grafted chains …”

Section: Resultsmentioning

confidence: 99%

“…The counterion specificity of the PMETAC brushes in aqueous solutions was investigated by the combination of QCM−D and SE with an ellipsometry‐compatible QCM−D module ,. The quartz crystal sensor with a fundamental resonance frequency of ∼5 MHz was mounted in a fluid cell with the sensing side exposed to the solution.…”

Section: Methodsmentioning

confidence: 99%

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Counterion Specificity of Polyelectrolyte Brushes: Role of Specific Ion‐Pairing Interactions

2018

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We demonstrate here that the properties of poly (2-(methacryloyloxy) ethyl trimethylammonium chloride) brushes can be tuned by counterion species. When the brushes are exposed to external chloride (Cl ) counterions, obvious dehydration and collapse are only observed at high salt concentrations. In the presence of very strongly chaotropic perchlorate (ClO ), the brushes strongly dehydrate and collapse at a very low salt concentration. For the strongly chaotropic thiocyanate ion (SCN ), the changes in hydration and conformation of the brushes are similar to those observed for ClO but at a smaller extent at very low salt concentrations. With the addition of kosmotropic acetate (Ac ), hydration of the brushes increases, accompanied by a swelling of the brushes in the low-salt-concentration regime. In contrast, the brushes dehydrate and collapse with increasing concentration of Ac in the high-salt-concentration regime. The counterion specificity of the brushes demonstrated here is determined by specific ion-pairing interactions through modulating the osmotic pressure within the brushes and the hydrophobicity of the ion pairs.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Counterion Specificity of Polyelectrolyte Brushes: Role of Specific Ion‐Pairing Interactions

2018

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“…Besides, there exists more hydrogen bonding between the deionized COOH and the CO of MPTC to form additional crosslinking in the hydrogel after immersing in HCl because the storage modulus decreases ≈66% by heating from 20 to 80 °C (Figure S4, Supporting Information) for the hydrogel after immersing in HCl, comparing the decrease of ≈43% during the same heating for the hydrogel after immersing in NaOH. Further study will be focused on the evolution of this interesting network of the present hydrogel in different pH solutions.…”

Section: Resultsmentioning

confidence: 99%

Polyampholyte Hydrogels with pH Modulated Shape Memory and Spontaneous Actuation

Zhang

Liao

Wang

et al. 2018

Adv Funct Materials

159

133

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Polyampholyte hydrogels are synthesized by one-step copolymerization of cationic monomer 3-(methacryloylamino)propyltrimethylammonium chloride, anionic monomers sodium p-styrenesulfonate (NaSS), and methacrylic acid (MAA) without chemical crosslinker and adding salts. The hydrogels exhibit pH responsive shape memory behavior; the temporary shape of the hydrogel is formed manually after immersing in NaOH solution and fixed in HCl solution, while the shape recovery occurs by immersing in NaOH again. Most interestingly, the hydrogel shows a spontaneous shape change after the first shape memory cycle. When the recovered hydrogel with a little residual deformation is immersed in HCl again, it twists spontaneously and rapidly to the previous temporary shape. The spontaneous twisting and recovering can be repeated for ten times. Furthermore, the hydrogel swells quickly and is strengthened in HCl, while shrinks and weakens in NaOH during the shape change procedure. This unique synergistic effect of fast swelling, residual helical deformation, and increased strength plays a significant role in the spontaneous shape alternation. This new finding will initiate a new prosperous design for new soft actuators requiring successive actions.

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“…[117] For polyelectrolyte brushes, the interchain hydrogen-bond network can be reorganized owing to the pH-induced adsorption-desorption balance of hydronium or hydroxide, as a result, oil-droplet adhesion also can be tuned by adjusting the pH value. [118] These pH-responsive surfaces have potential in the applications of microfluidic switching devices, drug delivery, biodetection, and bioseparation.…”

Section: Ph-responsive Surface Adhesionmentioning

confidence: 99%

External‐Field‐Induced Gradient Wetting for Controllable Liquid Transport: From Movement on the Surface to Penetration into the Surface

Zhang

et al. 2017

Advanced Materials

101

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External‐field‐responsive liquid transport has received extensive research interest owing to its important applications in microfluidic devices, biological medical, liquid printing, separation, and so forth. To realize different levels of liquid transport on surfaces, the balance of the dynamic competing processes of gradient wetting and dewetting should be controlled to achieve good directionality, confined range, and selectivity of liquid wetting. Here, the recent progress in external‐field‐induced gradient wetting is summarized for controllable liquid transport from movement on the surface to penetration into the surface, particularly for liquid motion on, patterned wetting into, and permeation through films on superwetting surfaces with external field cooperation (e.g., light, electric fields, magnetic fields, temperature, pH, gas, solvent, and their combinations). The selected topics of external‐field‐induced liquid transport on the different levels of surfaces include directional liquid motion on the surface based on the wettability gradient under an external field, partial entry of a liquid into the surface to achieve patterned surface wettability for printing, and liquid‐selective permeation of the film for separation. The future prospects of external‐field‐responsive liquid transport are also discussed.

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Reorganization of hydrogen bond network makes strong polyelectrolyte brushes pH-responsive

Abstract: The pH response of strong polyelectrolyte brushes originates from the pH-mediated reorganization of hydrogen bond network.

Cited by 50 publications

References 50 publications

Counterion Specificity of Polyelectrolyte Brushes: Role of Specific Ion‐Pairing Interactions

Counterion Specificity of Polyelectrolyte Brushes: Role of Specific Ion‐Pairing Interactions

Polyampholyte Hydrogels with pH Modulated Shape Memory and Spontaneous Actuation

External‐Field‐Induced Gradient Wetting for Controllable Liquid Transport: From Movement on the Surface to Penetration into the Surface

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