Energy Dissipation and Mechanoresponsive Color Evaluation of a Poly(n-hexyl Methacrylate) Soft Material Enhanced by a Mechanochromic Cross-Linker with Dynamic Covalent Bonds

2020 ◽  
Vol 53 (21) ◽  
pp. 9313-9324
Author(s):  
Yuchen Mao ◽  
Yuto Kubota ◽  
Takashi Kurose ◽  
Akira Ishigami ◽  
Kota Seshimo ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Soft Material ◽  
Covalent Bonds ◽  
Cross Linker ◽  
Hexyl Methacrylate

scholarly journals Injectable dynamic covalent hydrogels of boronic acid polymers cross-linked by bioactive plant-derived polyphenols

2018 ◽  
Vol 6 (9) ◽  
pp. 2487-2495 ◽  
Author(s):  
Zhuojun Huang ◽  
Peyman Delparastan ◽  
Patrick Burch ◽  
Jing Cheng ◽  
Yi Cao ◽  
...  
Keyword(s):  
Boronic Acid ◽  
Polyphenolic Compounds ◽  
Functionalized Polymers ◽  
Covalent Bonds ◽  
Cross Linker ◽  
And Function

Wisdom from nature: Plant-derived polyphenolic compounds can crosslink boronic acid functionalized polymers through formation of dynamic covalent bonds and function as both cross-linker and bioactive cargo.

scholarly journals A universal method to easily design tough and stretchable hydrogels

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Chisa Norioka ◽  
Yuino Inamoto ◽  
Chika Hajime ◽  
Akifumi Kawamura ◽  
Takashi Miyata
Keyword(s):  
Energy Dissipation ◽  
Polymer Chain ◽  
Mechanical Performance ◽  
Monomer Concentration ◽  
High Water ◽  
High Water Content ◽  
Universal Method ◽  
Covalent Bonds ◽  
Physical And Chemical ◽  
Chain Entanglements

AbstractHydrogels are flexible materials that have high potential for use in various applications due to their unique properties. However, their applications are greatly restricted by the low mechanical performance caused by high water content and inhomogeneous networks. This paper reports a universal strategy for easily preparing hydrogels that are tough and stretchable without any special structures or complicated processes. Our strategy involves tuning the polymerization conditions to form networks with many polymer chain entanglements to achieve energy dissipation. Tough and stretchable hydrogels can be prepared by free radical polymerization with a high monomer concentration and low cross-linker content to optimize the balance between physical and chemical cross-links by entanglements and covalent bonds, respectively. The strategy of using polymer chain entanglements for energy dissipation allows us to overcome the limitation of low mechanical performance, which leads to the wide practical use of hydrogels.

A polyester–polystyrene hybrid connected by dynamic covalent bonds prepared via radical polymerization of styrene in a “RAFT gel”

2014 ◽  
Vol 5 (11) ◽  
pp. 3689-3696 ◽  
Author(s):  
Daiki Yoshimura ◽  
Shinji Yamada ◽  
Akinori Takasu
Keyword(s):  
Radical Polymerization ◽  
Chain Transfer ◽  
Vinyl Monomers ◽  
Covalent Bonds ◽  
Reversible Addition ◽  
Cross Linker

We cross-linked the polyester chains with 1,1-thiocarbonyldiimidazole to form a reversible addition–fragmentation chain-transfer (RAFT) gel, in which the trithiocarbonate moiety acted as a cross-linker. The “RAFT gel” was then swollen in vinyl monomers and styrene was radically polymerized within the gel, in which the polyester and polystyrene segments were miscible at the segment level.

Temperature Dependence of the Critical Electron Dose for Fatty Acid Monolayers

1982 ◽  
Vol 40 ◽  
pp. 78-79
Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser
Keyword(s):  
Electron Beam ◽  
Fatty Acid ◽  
Inelastic Scattering ◽  
Temperature Dependence ◽  
Structural Damage ◽  
Direct Result ◽  
Second Step ◽  
Strong Temperature Dependence ◽  
Electron Dose ◽  
Covalent Bonds

The structural damage of molecules irradiated by electrons is generally considered to occur in two steps. The direct result of inelastic scattering events is the disruption of covalent bonds. Following changes in bond structure, movement of the constituent atoms produces permanent distortions of the molecules. Since at least the second step should show a strong temperature dependence, it was to be expected that cooling a specimen should extend its lifetime in the electron beam. This result has been found in a large number of experiments, but the degree to which cooling the specimen enhances its resistance to radiation damage has been found to vary widely with specimen types.

Structural Transformation of a Germanium Σ=13 (510) [001] Tilt Grain Boundary under the Electron Beam

1990 ◽  
Vol 48 (1) ◽  
pp. 52-53 ◽  
Author(s):  
Jean-Luc Rouvière ◽  
Alain Bourret
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Structural Transformation ◽  
Mirror Symmetry ◽  
High Resolution Electron Microscopy ◽  
Structural Transformations ◽  
Covalent Bonds ◽  
Resolution Electron ◽  
Tilt Grain Boundary

The possible structural transformations during the sample preparations and the sample observations are important issues in electron microscopy. Several publications of High Resolution Electron Microscopy (HREM) have reported that structural transformations and evaporation of the thin parts of a specimen could happen in the microscope. Diffusion and preferential etchings could also occur during the sample preparation.Here we report a structural transformation of a germanium Σ=13 (510) [001] tilt grain boundary that occurred in a medium-voltage electron microscopy (JEOL 400KV).Among the different (001) tilt grain boundaries whose atomic structures were entirely determined by High Resolution Electron Microscopy (Σ = 5(310), Σ = 13 (320), Σ = 13 (510), Σ = 65 (1130), Σ = 25 (710) and Σ = 41 (910), the Σ = 13 (510) interface is the most interesting. It exhibits two kinds of structures. One of them, the M-structure, has tetracoordinated covalent bonds and is periodic (fig. 1). The other, the U-structure, is also tetracoordinated but is not strictly periodic (fig. 2). It is composed of a periodically repeated constant part that separates variable cores where some atoms can have several stable positions. The M-structure has a mirror glide symmetry. At Scherzer defocus, its HREM images have characteristic groups of three big white dots that are distributed on alternatively facing right and left arcs (fig. 1). The (001) projection of the U-structure has an apparent mirror symmetry, the portions of good coincidence zones (“perfect crystal structure”) regularly separate the variable cores regions (fig. 2).

Energy Dissipation Processes of Singlet Excited 1-Hydroxyfluorenone and its Hydrogen-Bonded Complex with N-Methylimidazole

2004 ◽  
Author(s):  
Krisztina Sebők-Nagy ◽  
László Biczók ◽  
Akimitsu Morimoto ◽  
Tetsuya Shimada ◽  
Haruo Inoue
Keyword(s):  
Energy Dissipation ◽  
Dissipation Processes ◽  
Hydrogen Bonded
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