Effect of Counterion Binding to Swelling of Polyelectrolyte Brushes

Ji, Chunda; Zhou, Chao; Zhao, Bintao; Yang, Jingfa; Zhao, Jiang

doi:10.1021/acs.langmuir.1c00309

Cited by 13 publications

(27 citation statements)

References 61 publications

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“…Excellent mechanical properties of the hydrogel broaden its application range and make it possible for its long-term role in marine antifouling and oil pollution prevention. Hydrophilic hydrogels are easily swollen in water, thereby affecting the mechanical properties. − As shown in Figure , the PVA/Gly hydrogel presented poor mechanical strength (0.58 MPa). After TA was introduced into the hydrogel through hydrogen bond interaction, the mechanical strength of the hydrogel increased to 1.30 MPa.…”

Section: Results and Discussionmentioning

confidence: 99%

Transparent Janus Hydrogel Wet Adhesive for Underwater Self-Cleaning

Feng

Yang

et al. 2021

ACS Appl. Mater. Interfaces

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The optical window is a key part of a sensor specially used for oceanographic detection, but it is often severely affected by marine biofouling and oil pollution, resulting in reduced transparency and lifespan. Hydrogel, as a hydrophilic polymer network, has excellent antifouling effects with good transparency, but it is difficult to adhere to substrates, which greatly limits its practical applications. To solve the above problem, a transparent Janus hydrogel wet adhesive was prepared through modifying poly(vinyl alcohol)/glycerol–tannic acid/Cu2+ (PVA/Gly-TA/Cu2+) hydrogel with the underwater adhesive poly(dopamine methacrylamide-co-methoxyethyl acrylate) (P(DMA-co-MEA)) via the coordination effect between Cu2+ and catechol. Even when coated with adhesive, the sample still retained good transmittance. The presence of Cu2+ endowed the hydrogel with better tensile strength and, at the same time, can improve the adhesion of the hydrogel to the substrate through the coordination effect with the adhesive. The tensile stress of Janus hydrogels can even reach 4.4 MPa, and the adhesion strength of the obtained Janus hydrogel can reach about 14 kPa in seawater. Furthermore, the Cu-rich Janus hydrogel presented a significant inhibitory effect on the growth of surface algae. The oil contact angle of the Janus hydrogel was as high as 148° underwater. After the hydrogel was reswollen, there were lower algae densities on the surfaces of the hydrogel and little change in transparency. Considering the above properties, this novel Janus hydrogel is anticipated to be a promising protective material to solve the marine pollution problem confronting optical equipment.

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Section: Results and Discussionmentioning

confidence: 99%

Transparent Janus Hydrogel Wet Adhesive for Underwater Self-Cleaning

Feng

Yang

et al. 2021

ACS Appl. Mater. Interfaces

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“…Accordingly, specific counterion effects in these systems refer to the ability of counterions to influence these two swelling mechanisms. Although it has been experimentally observed that specific counterion effects on the swelling behavior of polyelectrolyte brushes follow the Hofmeister series, various explanations, for example, ion hydrophobicity/hydrophilicity and ion-pair formation between counterions and immobile charges on the polyelectrolytes, have been used to rationalize the observations. − For example, Murdoch et al suggested that ion hydrophobicity can solely explain the specific ion effects in a hydrophobic weak polyelectrolyte brush. On the other hand, Zimmermann et al and Higaki et al demonstrated that ion-pair formation with weakly hydrated anions reduces the thickness of strong polyelectrolyte brushes at low ionic strength (where the ion osmotic effect is pronounced).…”

Section: Introductionmentioning

confidence: 99%

Specific Counterion Effects on the Swelling Behavior of Strong Polyelectrolyte Brushes

et al. 2022

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It is well known that specific types of counterions affect the hydration of polyelectrolytes both in the bulk and at interfaces, but the mechanisms of this effect have not yet been fully understood. In this work, we have designed a model system, consisting of imidazolium-based cationic polyelectrolyte brushes with controlled grafting densities, to systematically investigate how specific counterion properties affect well-established swelling mechanisms in brushes. With this approach, we show that two swelling mechanisms, namely, counterion influence on the ion osmotic pressure and counterion influence on brush−solvent nonelectrostatic interactions, are simultaneously at play. Here, we demonstrate that the former effect can be related to the polarizability of the counterions, while the latter effect can be correlated to the hydration enthalpy of the counterions. We further demonstrate that the interplay of these two mechanisms depends on the brush grafting density and ionic strength of the medium such that under certain conditions, one effect can dominate over the other. Specifically, at low ionic strength and low grafting density, swelling of the brush is significantly influenced by the polarizability of counterions, while at high grafting density and high ionic strength, the hydration enthalpy of ions is the dominating factor. Moreover, by employing a theoretical model, we rationalize the experimental findings and further quantify the contribution of specific counterion effects as a function of grafting density and ionic strength. We believe such an approach improves the general understanding of the influence of ions on the polyelectrolyte brush swelling and even beyond.

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“…This tendency agrees with a previous report on the ion penetration and swelling dynamics of a PSS brush on a QCM chip. [ 48 ] Each trend follows an empirical scaling‐law:

\begin{matrix} τ_{normalG} = A {(λ_{+}^{0})}^{α - 1} \end{matrix}

where A is the time constant at a small ion size limit, and α is the ideality factor that indicates the degree of deviation from free diffusion at α = 0. The time constant ratio A ex /A in has only a slight variation from unity, indicating the gate response is almost symmetric over a wide range of cation species.…”

Section: Resultsmentioning

confidence: 99%

Correlation between Transient Response and Neuromorphic Behavior in Organic Electrochemical Transistors

Yamamoto

Polyravas

Han

et al. 2022

Adv Elect Materials

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The factors controlling the neuromorphic response of organic electrochemical transistors (OECTs) are examined. In these devices, the gate voltage is used to supply the pre‐synaptic input, while the drain current is taken as the post‐synaptic output. The behavior of devices made from polymer blends of a mixed conductor (PEDOT:PSS) and an ion conductor (PSSNa) is analyzed. The experimental results highlight that the post‐synaptic response timescale depends on the size of ion in the electrolyte. Modeling shows that the neuromorphic response is controlled by the transient response of the ionic circuit of the OECT. These insights on device response time pave the way for a more rational design of OECT‐based neuromorphic devices.

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Effect of Counterion Binding to Swelling of Polyelectrolyte Brushes

Cited by 13 publications

References 61 publications

Transparent Janus Hydrogel Wet Adhesive for Underwater Self-Cleaning

Transparent Janus Hydrogel Wet Adhesive for Underwater Self-Cleaning

Specific Counterion Effects on the Swelling Behavior of Strong Polyelectrolyte Brushes

Correlation between Transient Response and Neuromorphic Behavior in Organic Electrochemical Transistors

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