Ionic Correlations in Random Ionomers

Ma, Boran; Nguyen, Trung Dac; Pryamitsyn, Victor; Cruz, Mónica Olvera de la

doi:10.1021/acsnano.7b07432

Cited by 43 publications

(75 citation statements)

References 56 publications

(91 reference statements)

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“…The charge not only changes interfacial adsorption of these copolymers but can also modulate the self-assembled morphologies in bulk chloroform due to electrostatic correlation driven aggregation. 18…”

Section: Discussionmentioning

confidence: 99%

“…16 In organic media, on the other hand, ionic correlations in charge-containing copolymers lead to the formation of ionic clusters. 18−22 The ionic clusters can lead to nontrivial thermodynamic changes in the molten state, such as the evolution of inverted phases, 6,23 and ion-dependent miscibility of ion-conducting block copolymers. 24 Theoretical developments have identified the effects of ion–ion correlations, 25−29 solvation energy of ions, 30−33 and translational entropy of ions as significant influences on determining the thermodynamics of charge-containing copolymers.…”

Section: Introductionmentioning

confidence: 99%

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Self-Assembly of Charge-Containing Copolymers at the Liquid–Liquid Interface

et al. 2019

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Quantitatively understanding the self-assembly of amphiphilic macromolecules at liquid–liquid interfaces is a fundamental scientific concern due to its relevance to a broad range of applications including bottom-up nanopatterning, protein encapsulation, oil recovery, drug delivery, and other technologies. Elucidating the mechanisms that drive assembly of amphiphilic macromolecules at liquid–liquid interfaces is challenging due to the combination of hydrophobic, hydrophilic, and Coulomb interactions, which require consideration of the dielectric mismatch, solvation effects, ionic correlations, and entropic factors. Here we investigate the self-assembly of a model block copolymer with various charge fractions at the chloroform–water interface. We analyze the adsorption and conformation of poly(styrene)- block -poly(2-vinylpyridine) (PS- b -P2VP) and of the homopolymer poly(2-vinylpyridine) (P2VP) with varying charge fraction, which is controlled via a quaternization reaction and distributed randomly along the backbone. Interfacial tension measurements show that the polymer adsorption increases only marginally at low charge fractions (<5%) but increases more significantly at higher charge fractions for the copolymer, while the corresponding randomly charged P2VP homopolymer analogues display much more sensitivity to the presence of charged groups. Molecular dynamics (MD) simulations of the experimental systems reveal that the diblock copolymer (PS- b -P2VP) interfacial activity could be mediated by the formation of a rich set of complex interfacial copolymer aggregates. Circular domains to elongated stripes are observed in the simulations at the water–chloroform interface as the charge fraction increases. These structures are shown to resemble the spherical and cylindrical helicoid structures observed in bulk chloroform as the charge fraction increases. The self-assembly of charge-containing copolymers is found to be driven by the association of the charged component in the hydrophilic block, with the hydrophobic segments extending away from the hydrophilic cores into the chloroform phase.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Self-Assembly of Charge-Containing Copolymers at the Liquid–Liquid Interface

et al. 2019

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“…For matrix-free model systems [34,35] it was observed that NPs diffuse similarly to a polymer solution [36][37][38], while chains diffuse faster than NPs [39]. Ionic interactions are also included in the case of ionomers in which the morphology and phase behavior depend on the electrostatic strength [40][41][42]. In particular, ionic clusters are formed by increasing the electrostatic strength developed from linear to branched structures [40].…”

Section: Introductionmentioning

confidence: 99%

“…Ionic interactions are also included in the case of ionomers in which the morphology and phase behavior depend on the electrostatic strength [40][41][42]. In particular, ionic clusters are formed by increasing the electrostatic strength developed from linear to branched structures [40]. In a simulation of ionomer (poly(ethylene-co-methacrylic acid)) nanocomposites [43], it was observed that ions were depleted around a neutral NP, but they were denser relative to the bulk value in the case of a sticky NP.…”

Section: Introductionmentioning

confidence: 99%

Polymer Conformations, Entanglements and Dynamics in Ionic Nanocomposites: A Molecular Dynamics Study

et al. 2020

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We investigate nanoparticle (NP) dispersion, polymer conformations, entanglements and dynamics in ionic nanocomposites. To this end, we study nanocomposite systems with various spherical NP loadings, three different molecular weights, two different Bjerrum lengths, and two types of charge-sequenced polymers by means of molecular dynamics simulations. NP dispersion can be achieved in either oligomeric or entangled polymeric matrices due to the presence of electrostatic interactions. We show that the overall conformations of ionic oligomer chains, as characterized by their radii of gyration, are affected by the presence and the amount of charged NPs, while the dimensions of charged entangled polymers remain unperturbed. Both the dynamical behavior of polymers and NPs, and the lifetime and amount of temporary crosslinks, are found to depend on the ratio between the Bjerrum length and characteristic distance between charged monomers. Polymer–polymer entanglements start to decrease beyond a certain NP loading. The dynamics of ionic NPs and polymers is very different compared with their non-ionic counterparts. Specifically, ionic NP dynamics is getting enhanced in entangled matrices and also accelerates with the increase of NP loading.

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“…17 mV dec À 1 lower than that of Cu plate, implying the improved OER rate on a Cu/PVdF-HFP fibrous catalyst. The obtained Tafel slope value is little larger than the layered transition metal catalyst (e. g. 40 mV dec À 1 for NiFe-LDH in 1 M KOH [52] ), comparable with the transition metal oxide catalyst (e. g. 60 mV dec À 1 for Mn 3 O 4 in 1 M KOH [53] ) as well as the precious metal oxide catalysts (e. g. 55 mV dec À 1 for RuO 2 and 91 mV dec À 1 for IrO 2 in 0.5 M KOH [54] ), and smaller than the most of the perovskite-based catalysts (70 mV dec À 1 for LaCoO 3 and 91 mV dec À 1 for La 0.8 Sr 0.2 O 3 in 1 M KOH [20] ). It is unlikely that the unique fibrous structure of Cu/PVdF-HFP fiber catalyst affects the energetics of the OER; the much higher specific OER activity of Cu/PVdF-HFP fiber compared to the Cu plate is probably due to the synergetic effect between Cu and PVdF-HFP.…”

Section: Oxygen Evolution Reaction Activitymentioning

confidence: 70%

Electrospun Cu‐Deposited Flexible Fibers as an Efficient Oxygen Evolution Reaction Electrocatalyst

2019

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Developing oxygen evolution reaction (OER) catalysts with high activity, long‐term durability, and at low cost remains a great challenge. Herein, we report the high activity of fibrous Cu‐based catalysts. The synthesis process is simple and scalable. Electrospinning method was selected to synthesize fibrous polymer substrates (Poly(vinylidene fluoride‐co‐hexafluoropropylene, PVdF‐HFP), which are then covered by Cu via electroless deposition. Cu‐deposited PVdF‐HFP with different microstructures having smooth and roughened surfaces were also synthesized by drop‐casting and impregnation method, respectively, to emphasize the importance of the microstructures on OER activity. The OER activity and durability were studied by linear sweep voltammetry, chronoamperometry, and Tafel slope analysis. The Cu/PVdF‐HFP fibrous catalysts exhibit significantly improved OER activity and durability compared with Cu plate as well as Cu‐deposited PVdF‐HFP with different microstructures. The unique fibrous structure provides better mass transport, diffusion, and large active surface area. In addition to the advantages of the fibrous structure, attenuated total reflection infrared (ATR‐IR) and ex situ X‐ray photoelectron spectroscopy revealed that the improved specific activity for Cu/PVdF‐HFP fiber can be attributed to the synergistic effect between Cu and Cu/PVdF‐HFP (electron transfer from Cu to PVdF‐HFP) at the Cu|PVdF‐HFP interface, which results in optimized reaction energetics for the OER.

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Ionic Correlations in Random Ionomers

Cited by 43 publications

References 56 publications

Self-Assembly of Charge-Containing Copolymers at the Liquid–Liquid Interface

Self-Assembly of Charge-Containing Copolymers at the Liquid–Liquid Interface

Polymer Conformations, Entanglements and Dynamics in Ionic Nanocomposites: A Molecular Dynamics Study

Electrospun Cu‐Deposited Flexible Fibers as an Efficient Oxygen Evolution Reaction Electrocatalyst

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