High Elongation of Polyelectrolyte Chains in the Osmotic Limit of Spherical Polyelectrolyte Brushes:  A Study by Cryogenic Transmission Electron Microscopy

Wittemann, Alexander; Drechsler, Markus; Talmon, Yeshayahu; Ballauff, Matthias

doi:10.1021/ja0513234

Cited by 134 publications

(169 citation statements)

References 10 publications

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“…8a) [42]. By using cryo-TEM experiments, Wittemann et al demonstrated that under low-ionic strength, the chains of the brush layers in two opposing SPBs bend away when the SPBs are close to each other [42]. This low-ionic strength behavior of SPBs resembles the observation in the salt-free condition of the present study (Fig.…”

Section: Discussionsupporting

confidence: 85%

“…Under ionic solution, the sidearms are found to adopt a coiled conformation in both phosphorylation states. A similar transition from a stretched to coiled conformation has been observed experimentally for the interacting SBPs mentioned above [42]. The authors demonstrated that the polyelectrolyte chains are strongly stretched under low-ionic strength and assume a coiled conformation under high-ionic strength, i.e., in the limit of the salted brush.…”

Section: Discussionsupporting

confidence: 73%

“…It is interesting to point out that although the geometry is different, a similar behavior has been found in interacting spherical polyelectrolyte brushes (SPBs) (Fig. 8a) [42]. By using cryo-TEM experiments, Wittemann et al demonstrated that under low-ionic strength, the chains of the brush layers in two opposing SPBs bend away when the SPBs are close to each other [42].…”

Section: Discussionmentioning

confidence: 77%

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Conformational properties of interacting neurofilaments: Monte Carlo simulations of cylindrically grafted apposing neurofilament brushes

et al. 2012

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Neurofilaments are essential cytoskeletal filaments that impart mechanical stability to axons. They are mostly assembled from three neurofilament proteins that form the core of the filament and its sidearms. Adjacent neurofilaments interact with each other through their apposing sidearms and attain unique conformations depending on the ionic condition, phosphorylation state, and interfilament separations. To understand the conformational properties of apposing sidearms under various conditions and gain insight into interfilament interactions, we performed Monte Carlo simulations of neurofilament pairs. We employed a sequence-based coarse-grained model of apposing NF sidearms that are end-tethered to cylindrical geometries according to the stoichiometry of the three neurofilament subunits. Monte Carlo simulations were conducted under different conditions such as phosphorylation state, ionic condition, and interfilament separations. Under saltfree conditions, apposing sidearms are found to adopt mutually excluding stretched but bent away conformations that are reminiscent of a repulsive type of interaction. Under physiological conditions, apposing sidearms are found to be in a coiled conformation, suggesting a short-range steric repulsive type of interaction. Increased sidearm mutual interpenetration and a simultaneous decrease in the individual brush heights were observed as the interfilament separation was reduced from 60 to 40 nm. The observed conformations suggest entropic interaction as a likely mechanism for sidearm-mediated interfilament interactions under physiological conditions. Electronic supplementary materialThe online version of this article

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Section: Discussionsupporting

confidence: 85%

Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 77%

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Conformational properties of interacting neurofilaments: Monte Carlo simulations of cylindrically grafted apposing neurofilament brushes

et al. 2012

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“…Moreover, no staining agent has been used to enhance the contrast between the objects and the surrounding medium (for details of the general procedure cf. ref 11).…”

mentioning

confidence: 99%

Single Lamella Nanoparticles of Polyethylene

Weber¹,

Chiche²,

Krausch³

et al. 2007

Nano Lett.

116

142

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We present a complete analysis of the structure of polyethylene (PE) nanoparticles synthesized and stabilized in water under very mild conditions (15°C, 40 atm) by a nickel-catalyzed polymerization in aqueous solution. Combining cryogenic transmission electron microscopy (cryo-TEM) with X-ray scattering, we demonstrate that this new synthetic route leads to a stable dispersion of individual PE nanoparticles with a narrow size distribution. Most of the semicrystalline particles have a hexagonal shape (lateral size 25 nm, thickness 9 nm) and exhibit the habit of a truncated lozenge. The combination of cryo-TEM and small-angle X-ray scattering demonstrates that the particles consist of a single crystalline lamella sandwiched between two thin amorphous polymer layers ("nanohamburgers"). Hence, these nanocrystals that comprise only ca. 14 chains present the smallest single crystals of PE ever reported. The very small thickness of the crystalline lamella (6.3 nm) is related to the extreme undercooling (more than 100°C) that is due to the low temperature at which the polymerization takes place. This strong undercooling cannot be achieved by any other method so far. Dispersions of polyethylene nanocrystals may have a high potential for a further understanding of polymer crystallization as well as for materials science as, e.g., for the fabrication of extremely thin crystalline layers.Polyethylene (PE) is a commodity polymer that has become ubiquitous over the past several decades because of its low price and good mechanical properties. 1 Hence, the number of applications of the material is huge and many millions of tons are produced worldwide annually. However, PE has hardly played any role in the field of nanotechnology. This is due to the problem that PE is produced either by free radical polymerization under high pressure and temperature or with metal-organic catalysts working exclusively under strictly water-free conditions. Polymer nanoparticles and their composites with inorganic compounds, however, are very often produced in aqueous systems. 2 Recently, it was demonstrated that ethylene can be polymerized in aqueous systems in a catalytic fashion by Ni(II) complexes. [3][4][5][6] By virtue of this novel synthesis, long chains of polyethylene can be generated in a well-controlled environment and at ambient temperature. Thus, it could be shown that aqueous PE dispersions can be produced. This novel way of polymerization hence opens the way for the creation of nanostructures made from PE. Up to now, the particles synthesized in this way were semicrystalline and for the largest part consisted of stacks of several crystalline lamellae. 6

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“…The ITO electrodes were chemically modified with P DMAEMA brushes using the "grafting-to" method (Wittemann et al, 2005) according to the following procedure. ITO-coated glass slides were cut into 30 mm × 8 mm strips.…”

Section: Modification Of Electrodesmentioning

confidence: 99%

SMART POLYMER MODIFIED ELECTRODE SWITCHED BY IONIC STRENGTH AND pH

Sempionatto¹,

Perez²,

Basso³

et al. 2015

Anais Do XX Congresso Brasileiro De Engenharia Química

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-Poly(N,N-dimethylaminoethyl methacrylate) modified ITO (indium tin oxide) covered with gold nanoparticles electrode was synthesized by grafting to method and stimuli responses to pH and ionic strength (IS) was evaluated in PBS solution. At pH<5 PDMAEMA chains were found to be stretched generating a great electrochemical signal and at pH<5 collapsed with a signal decreasing. In IS≤0.001 molL -1 NaCl polymer chains were stretched and IS≥0.001mol L -1 collapsed. An interesting fact was observed when adding 0.001 molL -1 NaCl in a pH 7.40 solution, the signal response was increased comparing to pH 7.40 and 0 molL -1 NaCl, but when adding 0.001 molL -1 NaCl to a pH 3.00 solution, the signal response was decreased. This behavior can be explained in terms of protonation/deprotonation process and polymer brush regime. PDMAEMA brushes response was investigated by localized surface plasmonic resonance measurements (L-SPR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).

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High Elongation of Polyelectrolyte Chains in the Osmotic Limit of Spherical Polyelectrolyte Brushes: A Study by Cryogenic Transmission Electron Microscopy

Cited by 134 publications

References 10 publications

Conformational properties of interacting neurofilaments: Monte Carlo simulations of cylindrically grafted apposing neurofilament brushes

Conformational properties of interacting neurofilaments: Monte Carlo simulations of cylindrically grafted apposing neurofilament brushes

Single Lamella Nanoparticles of Polyethylene

SMART POLYMER MODIFIED ELECTRODE SWITCHED BY IONIC STRENGTH AND pH

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