Suppression of Proton Mobility by Hydrophobic Hydration

Bonn, Mischa; Bakker, Huib J.; Rago, Gianluca; Pouzy, Frederick; Siekierzycka, Joanna R.; Brouwer, Albert M.; Bonn, Daniel

doi:10.1021/ja9083094

Cited by 27 publications

(42 citation statements)

References 16 publications

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“…In order to interpret it, the concepts of hydration and hydrophobic effect conventionally discussed in the aqueous phase were introduced to the amphiphobic segment-alcohol interactions because alcohol is similarly to water in the aspect of H-bonds network. It is said, according to the water dynamics that the re-orientation time scale of Hbond near to the interface of hydrophobic segment/water was much slower than anywhere in the bulk water, [31] and the diffusion rate of protons [32] or charge transfer [33] was greatly suppressed by the hydrophobic hydration, protons accumulated on the surface of amphiphobic segments. In this paper, we try to inspire this thought into the mechanism of particle formation in the soap-free emulsion polymerization because it is a common knowledge that the hydration of monomer molecule and polymer chain in the aqueous phase and/or in the particle, and so incurred hydrophobic effect do exist in the heterophase polymerization system, however, so far it is rarely discussed in the formation of particles.…”

Section: Propositionmentioning

confidence: 99%

Roles of Proton in the Formation of Particles: Soap‐free Emulsion Polymerization of Styrene using AIBN and Potassium Persulfate as Initiators

Xia

Qian

et al. 2021

ChemistrySelect

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In this paper, the hydrophobic effect or hydration of hydrophobe was firstly introduced into the mechanism of polystyrene particles formation. Negatively charged surface of hydration shell was proposed due to the ordered structure of water molecules. Consequentially the concentration of hydrophobic chains depended on pH because protons destroyed the hydration shell, thereby extruded hydrophobic chains from the H-bonds networks. The soap-free emulsion polymerization of styrene by using AIBN (azodiisobutyronitrile) and KPS (Potassium Persulfate), respectively was performed at various pHs. It was proved that protons played a crucial role on the formation of PSt (polystyrene) particles. By using AIBN, particles were not prepared at pH 2.0 (HAc), pH 4.0 (HCl) and pH 2.0 (HCl), whereas by using KPS, particles were obtained regardless to pH. It indicated that anions of sulfate greatly enhanced the tolerance of hydration shell to the suffering from protons. Meanwhile, the roles of polymerization in the monomer phase, aqueous phase and growing particles were elucidated. By using AIBN, ca. 30 % PSt with M n (Numeral average molecular weight) = 300-1500 formed in the monomer phase at pH 6.8, which dissolved in water at pH 8.0 and pH 10.0. By using KPS, ca. 20 % and 30 % conversion of St were found in the aqueous phase at pH 2.0 (HCl) and pH 10.0 (NaOH), respectively. At pH 2.0 (HCl), oligomers generated in the aqueous phase were protonated, whereas at pH 10.0 (NaOH), they were soluble due to the seriously suppressed dissociation of water. At other pHs, oligomers captured protons, thereby relieved particles and interface from the suffering of protons. As the concentration of oligomers increased, oligomers precipitated to form clusters due to the increase of average number of protons on the surface of oligomers hydration shell, which successively incorporated into the growing particles, thus enlarged PDI (Polydispersity index) of MW (Weight-average molecular weight) distribution in particles. By using AIBN, owing to the limited partition of AIBN in the interfacial layer of St phase, the flat-roof peaks of GPC curves were observed, namely that the weight fraction of M i was constant. It implies that the freeradicals are living in the growing particles.

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Section: Propositionmentioning

confidence: 99%

Roles of Proton in the Formation of Particles: Soap‐free Emulsion Polymerization of Styrene using AIBN and Potassium Persulfate as Initiators

Xia

Qian

et al. 2021

ChemistrySelect

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“…One strategy that has successfully been used to gain access to out-of-equilibrium species of a self-assembly system relies on microfluidics. 20,21 For instance, it has been used for real time monitoring [22][23][24] and control 25,26 of chemical reactions, following mixing reactions, 27,28 steer molecular self-assembly 29,30 and study (out-of-equilibrium) reactions in biological systems. [31][32][33] In this paper, we use a lab-on-a-chip approach as a means to achieve out-of-equilibrium control over the structural hierarchy of an artificial light-harvesting complex: double-walled molecular nanotubes.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic out-of-equilibrium control of molecular nanotubes

Kriete

Feenstra

Pshenichnikov

2020

Phys. Chem. Chem. Phys.

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The bottom-up fabrication of functional nanosystems for light-harvesting applications and excitonic devices often relies on molecular self-assembly. Gaining access to the intermediate species involved in self-assembly would provide valuable insights into the pathways via which the final architecture has evolved, yet difficult to achieve due to their intrinsically short-lived nature. Here, we employ a lab-on-a-chip approach as a means to obtain in situ control of the structural complexity of an artificial light-harvesting complex: molecular double-walled nanotubes. Rapid and stable dissolution of the outer wall was realized via microfluidic mixing thereby rendering the thermodynamically unstable inner tubes accessible to spectroscopy. By measurement of the linear dichroism and time-resolved photoluminescence of both double-walled nanotubes and isolated inner tubes we show that the optical (excitonic) properties of the inner tube are remarkably robust to such drastic perturbation of the system's supramolecular structure as removal of the outer wall. The developed platform is readily extendable to a broad range of practical applications such as e.g. self-assembling systems and molecular photonics devices.

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“…tion retarded by hydrophobic groups. 13 However, it has also been proposed that the reduction of the proton mobility in solutions is caused by microscopic phase separation induced by water clustering at high solute concentrations. 14 To shed light on this issue, simulations at the atomic level are needed.…”

Section: Introductionmentioning

confidence: 99%

Proton transport in a binary biomimetic solution revealed by molecular dynamics simulation

Liang

Jansen

2011

The Journal of Chemical Physics

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We report the simulation results of the proton transport in a binary mixture of amphiphilic tetramethylurea (TMU) molecules and water. We identify different mechanisms that either facilitate or retard the proton transport. The efficiency of these mechanisms depends on the TMU concentration. The overall picture is more complicated than a recent suggestion that the presence of amphiphilic molecules suppresses the proton mobility by slowing down the reorientation of the surrounding water molecules. It has also been suggested that the hydronium ion induces local water orientational order, which results in an ordered region that has to move along with the proton potentially slowing down the proton transport as suggested by experiment. We find that water-wire like structures formed at low amphiphile concentrations facilitate proton transfer, and reduction of the hydrogen bond connectivity induced at high concentrations retards it.

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Suppression of Proton Mobility by Hydrophobic Hydration

Cited by 27 publications

References 16 publications

Roles of Proton in the Formation of Particles: Soap‐free Emulsion Polymerization of Styrene using AIBN and Potassium Persulfate as Initiators

Roles of Proton in the Formation of Particles: Soap‐free Emulsion Polymerization of Styrene using AIBN and Potassium Persulfate as Initiators

Microfluidic out-of-equilibrium control of molecular nanotubes

Proton transport in a binary biomimetic solution revealed by molecular dynamics simulation

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