Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications

基礎講座 電気泳動(Electrophoresis)

In this review, a brief synopsis of superhydrophobicity (i.e. extreme non-wettability) and its implications on marine fouling are presented. A short overview of wettability and recent experimental developments aimed at fabricating superhydrophobic surfaces by tailoring their chemical nature and physical appearance (i.e. substratum texture) are reviewed. The formation of responsive/"smart" surfaces, which adjust their physico-chemical properties to variations in some outside physical stimulus, including light, temperature, electric field, or solvent, is also described. Finally, implications of tailoring the surface chemistry, texture, and responsiveness of surfaces on the design of effective marine fouling coatings are considered and discussed.

Recent developments in superhydrophobic surfaces and their relevance to marine fouling: a review

Small Angle Scattering of X-Rays

The English-language dictionary defines wrinkles as “small furrows, ridges, or creases on a normally smooth surface, caused by crumpling, folding, or shrinking”. In this paper we review the scientific aspects of wrinkling and the related phenomenon of buckling. Specifically, we discuss how and why wrinkles/buckles form in various materials. We also describe several examples from everyday life, which demonstrate that wrinkling or buckling is indeed a commonplace phenomenon that spans a multitude of length scales. We will emphasize that wrinkling is not always a frustrating feature (e.g., wrinkles in human skin), as it can help to assemble new structures, understand important physical phenomena, and even assist in characterizing chief material properties.

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Soft matter with hard skin: From skin wrinkles to templating and material characterization

Stiff thin films on soft substrates are both ancient and commonplace in nature; for instance, animal skin comprises a stiff epidermis attached to a soft dermis. Although more recent and rare, artificial skins are increasingly used in a broad range of applications, including flexible electronics, tunable diffraction gratings, force spectroscopy in cells, modern metrology methods, and other devices. Here we show that model elastomeric artificial skins wrinkle in a hierarchical pattern consisting of self-similar buckles extending over five orders of magnitude in length scale, ranging from a few nanometres to a few millimetres. We provide a mechanism for the formation of this hierarchical wrinkling pattern, and quantify our experimental findings with both computations and a simple scaling theory. This allows us to harness the substrates for applications. In particular, we show how to use the multigeneration-wrinkled substrate for separating particles based on their size, while simultaneously forming linear chains of monodisperse particles.

http://www.hpmsl.neu.edu/content/2005Papers/nmat1342.pdf

Nested self-similar wrinkling patterns in skins.

Stiff thin films on soft substrates are both ancient and commonplace in nature; for instance, animal skin comprises a stiff epidermis attached to a soft dermis. Although more recent and rare, artificial skins are increasingly used in a broad range of applications, including flexible electronics1, tunable diffraction gratings2,3, force spectroscopy in cells4, modern metrology methods5, and other devices6,7,8. Here we show that model elastomeric artificial skins wrinkle in a hierarchical pattern consisting of self-similar buckles extending over five orders of magnitude in length scale, ranging from a few nanometres to a few millimetres. We provide a mechanism for the formation of this hierarchical wrinkling pattern, and quantify our experimental findings with both computations and a simple scaling theory. This allows us to harness the substrates for applications. In particular, we show how to use the multigeneration-wrinkled substrate for separating particles based on their size, while simultaneously forming linear chains of monodisperse particles.

http://absimage.aps.org/image/MAR05/MWS_MAR05-2004-003984.pdf

Nested self-similar wrinkling patterns in skins

We extended the self-assembly concepts of macromolecules in solutions to create a variety of unique nanosized polymeric core-shell nanoparticles by means which allow scale-up for industrial production. This paper describes the synthesis methods and the mechanisms governing the design of structural features required for a beneficial use as performance-enhancing additives in rubber vulcanizates as well as the performance of such rubber compositions. The nanoparticles were prepared by the polymerization of block copolymers and their self-assembly in solvents into micelles followed by a subsequent stabilization of their structure by core cross- linking. Depending on the type and macrostructure of the block copolymers, the solvent, the concentration, and other process parameters, a variety of core-shell nanoparticles of different shapes (spheres, hollow spheres, ellipsoids, linear and branched strings, etc.) and sizes have been reproducibly synthesized. Most of the nanoparticles were composed of a solid, highly cross-linked core and an elastomeric shell structure. The evolution and structure of the nanoparticles during the different process steps involved were examined and characterized. The unique performance of spherical nanoparticles as performance-enhancing additives and novel reinforcing agents was explored in rubber compounds. It was also shown that the basic spherical or string type nanoparticles can be used as templates for the design of composite structures comprising the basic polymeric nanoparticles and smaller organic, inorganic, or metallic substructures embedded in and attached to the elastomeric shell molecules.

Synthesis, Characterization, and Application of Novel Polymeric Nanoparticles

Tsagaropoulos and Eisenberg [Macromolecules 1995, 28, 396; Macromolecules 1995, 28, 6067] reported a second loss tangent (tan δ) peak in temperature-dependent viscoelastic data for various un-cross...

Further Consideration of Viscoelastic Two Glass Transition Behavior of Nanoparticle-Filled Polymers

The introduction of silanes to improve processability and properties of silica-reinforced rubber compounds is critical to the successful commercial use of silica as a filler in tires and other applications. The use of silanes to promote polymer–filler interactions is expected to limit the development of a percolated filler network and may also affect the mobility of polymer chains near the particles. Styrene-butadiene rubber (SBR) was reinforced with silica particles at a filler volume fraction of 0.19, and various levels of filler–filler shielding agent (n-octyltriethoxysilane) and polymer–filler coupling agent (3-mercaptopropyltrimethoxysilane) were incorporated. Both types of silane inhibited the filler flocculation process during annealing the uncured rubber materials, thus reducing the magnitude of the Payne effect. In contrast to the significant reinforcement effects noted in the strain-dependent shear modulus, the bulk modulus from hydrostatic compression was largely unaltered by the silan...

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Mindaugas Rackaitis

Papers

Nested self-similar wrinkling patterns in skins.

Nested self-similar wrinkling patterns in skins

Synthesis, Characterization, and Application of Novel Polymeric Nanoparticles

Further Consideration of Viscoelastic Two Glass Transition Behavior of Nanoparticle-Filled Polymers

Flocculation, reinforcement, and glass transition effects in silica-filled styrene-butadiene rubber