Self-healing systems based on disulfide–thiol exchange reactions

2013 ◽  
Vol 4 (18) ◽  
pp. 4955 ◽  
Author(s):  
Mark Pepels ◽  
Ivo Filot ◽  
Bert Klumperman ◽  
Han Goossens
Keyword(s):  
Self Healing ◽  
Exchange Reactions ◽  
Thiol Exchange

scholarly journals Synthesis of Self-Healing Waterborne Polyurethane Systems Chain Extended with Chitosan

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 503
Author(s):  
Dae-Il Lee ◽  
Seung-Hyun Kim ◽  
Dai-Soo Lee
Keyword(s):  
Control Sample ◽  
Waterborne Polyurethane ◽  
The Self ◽  
Chain Extension ◽  
Hydroxyl Groups ◽  
Self Healing ◽  
Exchange Reactions ◽  
Healing Efficiency ◽  
Chitosan Content ◽  
A Chain

In this study, the self-healing properties of waterborne polyurethane (WPU) were implemented by chitosan as a chain extender of polyurethane prepolymers. The physical properties and self-healing efficiency of WPU were studied by changing the molar fractions of chitosan from 0.1 to 0.3. After thermal treatment for 24 h at 110 °C, the self-healing efficiency for the tensile strength of the highest chitosan content (WPU-C3) was found to be 47%. The surface scratch was also completely restored. The efficiency of the sample with the lowest chitosan content (WPU-C1) was found to be 35%, while that of the control sample without chitosan (WPU-C0) was 4%. The self-healing properties of the as-prepared films were attributed to the exchange reactions between the hydroxyl groups of chitosan and the urethane groups in the films at elevated temperature. It is inferred that self-healing WPU can be synthesized by chain extension with chitosan.

Self-Healing Polymer Films Based on Thiol–Disulfide Exchange Reactions and Self-Healing Kinetics Measured Using Atomic Force Microscopy

2011 ◽  
Vol 45 (1) ◽  
pp. 142-149 ◽  
Author(s):  
Jeong Ae Yoon ◽  
Jun Kamada ◽  
Kaloian Koynov ◽  
Jake Mohin ◽  
Renaud Nicolaÿ ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Polymer Films ◽  
Self Healing ◽  
Exchange Reactions ◽  
Force Microscopy ◽  
Disulfide Exchange ◽  
Atomic Force

Ultrafast and Reversible Multiblock Formation by the SET-Nitroxide Radical Coupling Reaction

2010 ◽  
Vol 63 (8) ◽  
pp. 1227 ◽  
Author(s):  
Jakov Kulis ◽  
Craig A. Bell ◽  
Aaron S. Micallef ◽  
Michael J. Monteiro
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Elevated Temperatures ◽  
Click Reaction ◽  
Coupling Reaction ◽  
Nitroxide Radical ◽  
Self Healing ◽  
Exchange Reactions ◽  
Radical Coupling ◽  
End Groups

The single electron transfer-nitroxide radical coupling (SET-NRC) reaction has been used to produce multiblock polymers with high molecular weights in under 3 min at 50°C by coupling a difunctional telechelic polystyrene (Br-PSTY-Br) with a dinitroxide. The well known combination of dimethyl sulfoxide as solvent and Me6TREN as ligand facilitated the in situ disproportionation of CuIBr to the highly active nascent Cu0 species. This SET reaction allowed polymeric radicals to be rapidly formed from their corresponding halide end-groups. Trapping of these carbon-centred radicals at close to diffusion controlled rates by dinitroxides resulted in high-molecular-weight multiblock polymers. Our results showed that the disproportionation of CuI was critical in obtaining these ultrafast reactions, and confirmed that activation was primarily through Cu0. We took advantage of the reversibility of the NRC reaction at elevated temperatures to decouple the multiblock back to the original PSTY building block through capping the chain-ends with mono-functional nitroxides. These alkoxyamine end-groups were further exchanged with an alkyne mono-functional nitroxide (TEMPO–≡) and ‘clicked’ by a CuI-catalyzed azide/alkyne cycloaddition (CuAAC) reaction with N3–PSTY–N3 to reform the multiblocks. This final ‘click’ reaction, even after the consecutive decoupling and nitroxide-exchange reactions, still produced high-molecular-weight multiblocks efficiently. These SET-NRC reactions would have ideal applications in re-usable plastics and possibly as self-healing materials.

scholarly journals Degradation of Wheat Germ Agglutinin during Sourdough Fermentation

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 340
Author(s):  
Luis E. Rojas Tovar ◽  
Michael G. Gänzle
Keyword(s):  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Reductase Activity ◽  
Size Exclusion ◽  
Enzyme Linked Immunosorbent Assay ◽  
Gluten Free ◽  
Exchange Reactions ◽  
Exclusion Chromatography ◽  
Thiol Exchange ◽  
Fungal Protease

Non Celiac Wheat Sensitivity (NCWS) is an intolerance to wheat products and individuals with NCWS often adhere to a gluten free diet. However, gluten free diets are often associated with a reduced sensory and nutritional quality. Wheat Germ Agglutinin (WGA) is one of the wheat components linked to NCWS. This study explored the fate of WGA during sourdough fermentation. To assess the role of thiol-exchange reactions and proteolysis, sourdoughs were fermented with Fructilactobacillus sanfranciscensis DSM20451, F. sanfranciscensis DSM20451ΔgshR, which lacks glutathione reductase activity, or Latilactobacillus sakei TMW1.22, with or without addition of fungal protease. The conversion of WGA was determined by size exclusion chromatography of fluorescence-labeled WGA, and by enzyme-linked immunosorbent assay (ELISA). Commercial whole wheat flour contained 6.6 ± 0.7 μg WGA/g. After fermentation with L. sakei TMW1.22 and F. sanfranciscensis DSM20451, the WGA content was reduced (p < 0.05) to 2.7 ± 0.4 and 4.3 ± 0.3 μg WGA/g, respectively, while the WGA content remained unchanged in chemically acidified controls or in doughs fermented with F. sanfranciscensis DSM20451ΔgshR. Protease addition did not affect the WGA content. In conclusion, the fate of WGA during sourdough fermentation relates to thiol-exchange reactions but not to proteolytic degradation.

A molecular dynamics simulation on self-healing behavior based on disulfide bond exchange reactions

Polymer ◽  
2021 ◽  
Vol 212 ◽  
pp. 123111
Author(s):  
Xiangrui Zheng ◽  
Hua Yang ◽  
Yaguang Sun ◽  
Yongqin Zhang ◽  
Yafang Guo
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Disulfide Bond ◽  
Dynamics Simulation ◽  
Self Healing ◽  
Exchange Reactions ◽  
Behavior Based
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