Geometrically Controlled Mechanically Responsive Polyelectrolyte Tube Arrays

Han, Lin; Wang, Lifeng; Chia, Khek-Khiang; Cohen, Robert E.; Rubner, Michael F.; Boyce, Mary C.; Ortiz, Christine

doi:10.1002/adma.201102917

Cited by 19 publications

(28 citation statements)

References 29 publications

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“…Quantification of polymer rigidity can delineate the mechanical properties of polyelectrolyte materials and LbL composites as a function of pH. 7,56 framework capture by the simple concept of an electrostatic contour length, L e , and a contour ratio, A/a, similar to the renormalization of charge density reported in early investigations. 50,51 While providing a good fit of observed data, our modified version of the OSF formulation suggests a more general parametric study, with extension to longer length scales, variation in salt concentration (and thus κ −1 ), as well as rigidity of the macromolecules (P 0 ).…”

Section: Resultsmentioning

confidence: 98%

Variation of Weak Polyelectrolyte Persistence Length through an Electrostatic Contour Length

Cranford

Buehler

2012

Macromolecules

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There is currently no consensus that the classical perspective of electrostatic persistence length (the so-called Odijk−Skolnick−Fixman, or OSF, formulation), derived by equating changes in electrostatic energy with bending rigidity, is applicable to weak polyelectrolytes. Here, with a focus on polyelectrolyte chains of finite length at a single scale, we formulate a simple and general theoretical model featuring the electrostatic persistence length, P e , through the introduction of an electrostatic contour length, L e , such that the electrostatic energy balance is applicable to highly flexible charged polyelectrolytes (where the intrinsic stiffness, P 0 is on the order of P e ). To isolate the effect of ionization, only the salt-free regime is considered. At the upper limit (relatively rigid molecules), the new formulation converges to the classical OSF form, while the lower bound (highly flexible molecules) approaches proportionality to the Debye screening length, κ −1 . In general, the electrostatic persistence can be described retroactively by the Debye screening, κ −1 , and the ratio of electrostatic to intrinsic contour lengths, A/a, complementary to predictive theoretical formulations. The theory is validated via full atomistic molecular dynamics simulations of single, isolated model weak polyelectrolyte chains in explicit solventspecifically poly(acrylic acid), PAA, and poly(allylamine hydrochloride), PAH, both of which undergo significant increases in persistence length under ionization. An ensemble of equilibrated polymer states is obtained via temperature assisted sampling, implementing molecular dynamics to drive the polymers into physically accessible conformations via cyclical temperature fluctuations and equilibration.

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Section: Resultsmentioning

confidence: 98%

Variation of Weak Polyelectrolyte Persistence Length through an Electrostatic Contour Length

Cranford

Buehler

2012

Macromolecules

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“…This achievement represents a significant improvement over the efficiency state-of-the-art for multinuclear-complex based LECs, since it is the first time such a device breaks the 1% barrier for the EQE. We also note that the overall best performance from red-emitting LECs based on any of the incumbent emitters, in the form of an mononuclear ionic transition metal complex or a conjugated polymer, is an EQE of 9.51 % measured at a luminance of 154 cd/m 2 , 23 and that the herein introduced device thereby introduces the dinuclear complex as a serious contender for the emitting species in efficient LEC devices.…”

Section: Device Development and Characterizationmentioning

confidence: 86%

“…For instance, Zhou and co-workers report on the successful application of Ir and Pt homodinuclear complexes as the emitter in OLEDs that exhibit a very high efficiency, 13,22 while others have demonstrated well-performing OLED devices based on homodinuclear and heterodinuclear complexes that emit with a broad variety of emission colors at high efficiency. 2 The light-emitting electrochemical cell (LEC) features a number of distinct advantages over the OLED, notably the opportunity to employ a robust single-layer active material and air-stabile electrodes, [23][24][25][26][27][28][29] which in turn render the LEC an ideal candidate for a low-cost 30 and low-energy solution-based [31][32][33][34][35][36] fabrication. However, only a few examples on the employment of multinuclear complexes in LEC devices exist in the scientific literature.…”

Section: Introductionmentioning

confidence: 99%

An efficient heterodinuclear Ir(iii)/Pt(ii) complex: synthesis, photophysics and application in light-emitting electrochemical cells

et al. 2019

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“…2c). Due to lateral constraint from interfibrillar contact and fiber bundling, indentation parallel to the fiber axis can result in a continuous multiaxial stress field, leading to an indentation response similar to a material continuum, which is much less compliant than bending or buckling of discrete fibrils [48]. These effects together contribute to the observed anisotropy (Fig.…”

Section: Discussionmentioning

confidence: 99%

Micromechanical anisotropy and heterogeneity of the meniscus extracellular matrix

Han

et al. 2017

Acta Biomaterialia

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To understand how the complex biomechanical functions of the meniscus are endowed by the nanostructure of its extracellular matrix (ECM), we studied the anisotropy and heterogeneity in the micromechanical properties of the meniscus ECM. We used atomic force microscopy (AFM) to quantify the time-dependent mechanical properties of juvenile bovine meniscus at deformation length scales corresponding to the diameters of collagen fibrils. At this scale, anisotropy in the elastic modulus of the circumferential fibers, the major ECM structural unit, can be attributed to differences in fibril deformation modes: uncrimping when normal to the fiber axis, and laterally constrained compression when parallel to the fiber axis. Heterogeneity among different structural units is mainly associated with their variations in microscale fiber orientation, while heterogeneity across anatomical zones is due to alterations in collagen fibril diameter and alignment at the nanoscale. Unlike the elastic modulus, the time-dependent properties are more homogeneous and isotropic throughout the ECM. These results enable a detailed understanding of the meniscus structure-mechanics at the nanoscale, and can serve as a benchmark for understanding meniscus biomechanical function, documenting disease progression and designing tissue repair strategies.

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Geometrically Controlled Mechanically Responsive Polyelectrolyte Tube Arrays

Cited by 19 publications

References 29 publications

Variation of Weak Polyelectrolyte Persistence Length through an Electrostatic Contour Length

Variation of Weak Polyelectrolyte Persistence Length through an Electrostatic Contour Length

An efficient heterodinuclear Ir(iii)/Pt(ii) complex: synthesis, photophysics and application in light-emitting electrochemical cells

Micromechanical anisotropy and heterogeneity of the meniscus extracellular matrix

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