Molecular Understanding on the Underwater Oleophobicity of Self-Assembled Monolayers: Zwitterionic versus Nonionic

Cheng, Gang; Liao, Mingrui; Zhao, Daohui; Jian, Zhou

doi:10.1021/acs.langmuir.6b03988

Cited by 39 publications

(38 citation statements)

References 77 publications

(149 reference statements)

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“…This MD study also investigated the balance between charge, hydration, and molecular volume/chain density effects. The principal effects are illustrated in Figure 11 complexation, or "self-association", [71][72][73][74] of the charged sidechains is especially significant at "low" chain densities but still leads to lowered electrostatic potentials of the zwitterionic brushes compared to their uncharged (but polar) counterparts at all chain densities. Indeed, we emphasize in this study a highly dynamic nature of such transient charge complexation.…”

Section: Resultsmentioning

confidence: 99%

Atomistic Study of Zwitterionic Peptoid Antifouling Brushes

Cheung

Lau

2018

Langmuir

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Using molecular dynamics (MD) simulations, we study the molecular behavior and hydration properties of a set of zwitterionic "peptoid" brushes, grafted on a rutile surface, that has been previously reported to exhibit excellent resistance against protein adsorption and cell attachment. Peptoids are novel poly( N-substituted glycine) peptide mimics with the side chains attached to amide nitrogens. They constitute a unique model polymer system because hundreds of side chains have been demonstrated, and the exact chain length and sequence order of the residues/monomers may be specified in experiments. In this report, we vary the brush grafting density as well as the side chain/polymer molecular volume. We include in our study polysarcosine as an uncharged comparison with a small polymer chain cross-section. Sarcosine is the simplest peptoid residue with only a nominally hydrophobic methyl group as side chain, but is also reported to exhibit high antifouling performance. Overall, we show in detail how molecular volume and hydration effects are intertwined in a zwitterionic polymer brush. For example, the zwitterionic design significantly promotes extended chain conformations and could actually lower the overall electrostatic potential. Some properties promoted by the balanced charges, such as chain flexibility and hydration, increase more prominently at "low" to "intermediate" chain densities. These and other observations should provide insight on the molecular behavior of peptoids and inform the design of zwitterionic antifouling polymer brushes.

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Section: Resultsmentioning

confidence: 99%

Atomistic Study of Zwitterionic Peptoid Antifouling Brushes

Cheung

Lau

2018

Langmuir

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“…The obtained results demonstrated a mutual correlated interaction between oil/water wettability of polyelectrolytes in specific surrounding liquid media (Shi et al 2016). In addition, it is worth mentioning that molecular dynamics simulations have also been demonstrated to be an effective way in revealing the interaction mechanism of underwater oleophobicity of self-assembled monolayers (SAMs) with different head groups (Cheng et al 2017;Liao et al 2017).…”

Section: Introductionmentioning

confidence: 74%

Probing surface interactions of underwater oleophobic polyelectrolyte multilayers

Wang

et al. 2020

Pet. Sci.

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In the present work, the interaction mechanism of specific polyelectrolyte multilayers (PEMs), fabricated by layer-by-layer deposition of polydiallyldimethylammonium chloride (PDDA) and poly(sodium 4-styrenesulfonate) (PSS), is studied using atomic force microscopy. The underwater oil-repellency of PSS-capped PEMs was further explored by measuring the interaction forces between tetradecane droplets and PEMs-coated silica substrates under various salinities. The force curves were analyzed following the Stokes–Reynolds–Young–Laplace theoretical model. Desirable consistency was achieved between the experimental and theoretical calculations at low NaCl concentrations (0.1 mM and 1 mM); however, underestimation of the attractive force was found as the NaCl concentration increases to moderate (10 mM) and high (100 mM) levels. Discrepancy analyses and incorporated features toward a reduced surface charge density were considered based on the previous findings of the orientation of anionic benzenesulfonate moieties (Liu et al. in Angew Chem Int Ed 54(16):4851–4856, 2015. https://doi.org/10.1002/anie.201411992). Short-range steric hindrance interactions were further introduced to simulate “brush” effect stemming from nanoscale surface roughness. It is demonstrated in our work that the PSS-capped PEMs remains a stable underwater lipophobicity against high salinity, which renders it potential application in surface wetting modification and anti-fouling.

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“…In our previous works, 33‐35 a cylindrically shaped oil nanodroplet 36 was built to study the wetting behaviors of underwater oil droplet on different SAMs, including nonionic, ionic and mixed‐charged SAMs. Here, we continue using this model to simulate the underwater oleophobicity of six SB‐SAMs.…”

Section: Model and Simulation Methodsmentioning

confidence: 99%

Molecular simulations on the hydration and underwater oleophobicity of zwitterionic self‐assembled monolayers

et al. 2020

Self Cite

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Zwitterionic materials have attracted increasing attentions in the underwater super‐oleophobic applications for its strong hydration via electrostatic interactions. Herein, molecular dynamics simulations were used to investigate the hydration and underwater oleophobicity of sulfobetaine‐terminated self‐assembled monolayers (SB‐SAMs) with different carbon spacer lengths (CSL) between oppositely charged groups of SB molecules. Simulation results show that the hydration of SB‐SAMs is positively dependent on CSL; the underwater oleophobicity is strengthened and then weakened with the increase of CSL, reaching optimal performance when CSL = 3; adhesion force of oil droplet on SB‐SAMs is inversely correlated with their contact angles, reaching the minimum value when CSL = 3. Moreover, the addition of NaCl can weaken the self‐association of SB molecules resulted from interactions between cationic and anionic groups, which promotes hydration and enhances underwater oleophobicity of SB‐SAMs. These results will benefit for the design of novel zwitterion‐based materials for anti‐fouling and oil–water separation applications.

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Molecular Understanding on the Underwater Oleophobicity of Self-Assembled Monolayers: Zwitterionic versus Nonionic

Cited by 39 publications

References 77 publications

Atomistic Study of Zwitterionic Peptoid Antifouling Brushes

Atomistic Study of Zwitterionic Peptoid Antifouling Brushes

Probing surface interactions of underwater oleophobic polyelectrolyte multilayers

Molecular simulations on the hydration and underwater oleophobicity of zwitterionic self‐assembled monolayers

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