Molecular Tensile Testing Machines: Breaking a Specific Covalent Bond by Adsorption-Induced Tension in Brushlike Macromolecules

Park, Insun; Sheiko, Sergei S.; Nese, Alper; Matyjaszewski, Krzysztof

doi:10.1021/ma8026996

Cited by 80 publications

(94 citation statements)

References 17 publications

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“…As a proofof-concept study, we demonstrated selective scission of disulfide bonds (S-S) incorporated into the middle of a bottlebrush backbone although S-C, C-O and C-C bonds remained intact or their scission rate was much slower (Fig. 10a), because the bond dissociation energy of the S-S bond is lower [45]. Even if the force is not large enough to break the S-S bond, it can accelerate the reduction of the S-S bond by dithiothreitol (DTT) [4].…”

Section: Molecular Bottlebrushesmentioning

confidence: 94%

“…These advances in materials engineering do not dismiss the traditional challenges in fundamentals of mechanochemistry related to understanding the transduction of macroscopic strain to individual bonds. In addition to conventional mechanochemistry tools (grinding, ultrasonic irradiation, and elongational flows), advanced techniques, such as optical tweezers [36], magnetic tweezers [37,38], atomic force microscopy (AFM)-based force spectroscopy [39][40][41], micro-needle manipulation [42], biomembrane force probes [43], and targeted incorporation of mechanophores [44][45][46], have been developed to control forces on a single-molecule scale. Simultaneously, theoretical frameworks for mechanochemistry undergo continuous development, from early work by Eyring [47], Kramers [48], Zhurkov [49], and Bell [50] to more recent fundamental studies by Evans [51], Klein [52], Beyer [53], Hummer [54], Dudko [55], Marx [56], Martinez [8], and many others reviewed in [57].…”

Section: Introductionmentioning

confidence: 99%

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Molecular Mechanochemistry: Engineering and Implications of Inherently Strained Architectures

Sheiko

2015

Topics in Current Chemistry

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Mechanical activation of chemical bonds is usually achieved by applying external forces. However, nearly all molecules exhibit inherent strain of their chemical bonds and angles as a result of constraints imposed by covalent bonding and interactions with the surrounding environment. Particularly strong deformation of bonds and angles is observed in hyperbranched macromolecules caused by steric repulsion of densely grafted polymer branches. In addition to the tension amplification, macromolecular architecture allows for accurate control of strain distribution, which enables focusing of the internal mechanical tension to specific chemical bonds and angles. As such, chemically identical bonds in self-strained macromolecules become physically distinct because the difference in bond tension leads to the corresponding difference in the electronic structure and chemical reactivity of individual bonds within the same macromolecule. In this review, we outline different approaches to the design of strained macromolecules along with physical principles of tension management, including generation, amplification, and focusing of mechanical tension at specific chemical bonds.

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Section: Molecular Bottlebrushesmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Molecular Mechanochemistry: Engineering and Implications of Inherently Strained Architectures

Sheiko

2015

Topics in Current Chemistry

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“…Recently, polymer brush, defined as a one-dimensional brush possessing densely grafted side chains on a linear polymer main chain or solid surfaces, has attracted much more attention due to their unique properties and several potential applications [1,2], such as high aspect ratio nanowires [3], supersoft elastomers [4], nanotubes and hollowed nanoparticles [5][6][7], photonic crystals [8][9][10], molecular tensile machines [11,12], and nanoporous materials [13,14]. Polymer brush has also been used in the liquid crystal display application for realizing the controllable alignment of liquid crystalline molecules in the devices.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of a Liquid Crystalline Polyferrocenylsilane Brush

Xiong

Wang

Qin

et al. 2014

J Inorg Organomet Polym

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A grafted side chain liquid crystalline polymer brush with poly(ferrocenylsilane) as the main chain and poly{6-(4 0 -butyloxyphenyl 4 00 -benzoyl)hexyl acrylate} as side chain has been synthesized by atom transfer radical polymerization (ATRP) technique. For comparison, a linear liquid crystalline polymer, poly{6-(4 0 -butyloxyphenyl-4 0 -benzoyl)hexyl acrylate}, was prepared by conventional radical polymerization method. Both of them were characterized by NMR, FT-IR, GPC and TGA. Their liquid crystalline properties have been investigated by means of differential scanning calorimetry, polarizing mciroscope and X-ray scattering. The liquid crystal phase behavior research demonstrated that both of them were reversible thermotropic nematic phase in the high temperature region and smectic A phase in the low temperature region. In comparison with linear liquid crystalline polymer, liquid crystalline polyferrocenylsilane brush exhibited the lower glass transition temperature (T g ) and clearing point (T NI ). Results showed that the brush architecture made the alignment of the mesogens more difficult than those in its monomer and linear polymer.

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“…5,6 In addition, steric repulsion between the side chains generates significant mechanical tension in the backbone which can be tuned by varying the grafting density, solvent quality, and the side chain length. 7,8 Furthermore, a stable unimolecular micelle of cylindrical shape formed from amphiphilic molecular brush copolymers cannot dissociate in aqueous solution, which is one of the major disadvantages associated with polymer micelles formed from amphiphilic linear polymers. 9,10 Because of their nonspherical macromolecular geometries and lengths up to a few hundred nanometers, brush polymers have afforded numerous potential applications in nanoscience, such as molecular actuators, 11 templates for inorganic particles, 9 and as precursors for nanocapsules, 12 nanotubes, 13 and other carbon nanostructures.…”

Section: ■ Introductionmentioning

confidence: 99%

Synthesis and Characterization of Brush-Shaped Hybrid Inorganic/Organic Polymers Based on Polyphosphazenes

et al. 2012

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A series of densely grafted star-and combshaped molecular brushes composed of polystyrene, poly(tertbutyl acrylate), and poly(N-isopropylacrylamide) were prepared by atom transfer radical polymerization (ATRP) using either cyclotriphosphazenes or polyphosphazenes as initiators. The initiators were prepared by the introduction of a free hydroxyl group into the side chains of a phosphazene cyclic trimer and polymer, followed by esterification with 2-bromopropionyl bromide. The grafting conditions were optimized for various monomers. The kinetics of the reaction were firstorder with respect to the monomer concentration in both cyclotriphosphazene and polyphosphazene systems. The molecular weights of the resulting polymers were estimated by gel permeation chromatography (GPC). The side chains of the brush polymers were cleaved from the backbone and analyzed by GPC to confirm the synthesis of well-defined polymer brushes. Brushes based on poly(tert-butyl acrylate) were subjected to hydrolysis to yield negatively charged brushes. In addition, the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide) brush polymers was measured by both dynamic light scattering (DLS) and differential scanning calorimetry (DSC), exhibiting a sharp phase transition at 33°C. Furthermore, starand comb-block copolymers with a hard polystyrene core and a soft poly(tert-butyl acrylate) shell were also synthesized.

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Molecular Tensile Testing Machines: Breaking a Specific Covalent Bond by Adsorption-Induced Tension in Brushlike Macromolecules

Cited by 80 publications

References 17 publications

Molecular Mechanochemistry: Engineering and Implications of Inherently Strained Architectures

Molecular Mechanochemistry: Engineering and Implications of Inherently Strained Architectures

Synthesis and Characterization of a Liquid Crystalline Polyferrocenylsilane Brush

Synthesis and Characterization of Brush-Shaped Hybrid Inorganic/Organic Polymers Based on Polyphosphazenes

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