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Full-Text Articles in Macromolecular Substances
Turning Zwitterions Into Toughening Agents: Salt-Activated Microdomains In Poly(Vinyl Alcohol) Double-Network Hydrogels, Louis D. Zhang, Jintao Yang, Si Yu Zheng
Turning Zwitterions Into Toughening Agents: Salt-Activated Microdomains In Poly(Vinyl Alcohol) Double-Network Hydrogels, Louis D. Zhang, Jintao Yang, Si Yu Zheng
University Research
Zwitterionic hydrogels, although highly biocompatible, are widely regarded as mechanically fragile, with typical tensile strengths below 0.1 MPa, which restricts their use in load-bearing applications. Here, we address this limitation by integrating a polyzwitterionic network with a poly(vinyl alcohol) (PVA) network through high-speed pregelation agitation that enhances chain entanglement and induces flow orientation. By exploiting the salt-driven conformational transition of zwitterionic chains, a controlled salting-out step generates uniformly dispersed nanoscale microdomains that act as reversible energy-dissipating units. At the same time, balanced hydrogen bonding between the two networks moderates PVA crystallinity, limiting embrittlement while preserving elasticity. The resulting double-network hydrogel …
Exploring The Theoretical Foundation With Rupture And Delayed Rupture Experiments, Shi-Qing Wang, Junpeng Wang, Asal Y. Siavoshani, Cheng Liang
Exploring The Theoretical Foundation With Rupture And Delayed Rupture Experiments, Shi-Qing Wang, Junpeng Wang, Asal Y. Siavoshani, Cheng Liang
University Research
We carry out uniaxial continuous and step stretching of various cross-linked polymer networks to demonstrate how characteristics of rupture during continuous stretching and delayed rupture after step stretching can be used to probe the structure of the emergent kinetic activation theory of bond dissociation (KATBD) for elastomeric failure. Based on delayed rupture experiments, we show that the network lifetime tntw, taken as the incubation time tdel-rupt for delayed rupture, depends on temperature in an Arrhenius like manner and is exponentially sensitive to the degree of network stretching (depicted by the step-stretch ratio λss). Rupture at λb during continuous stretching for …
Nitroarene-Mediated Photo-Oxidative Deconstruction And Upcycling Of Unsaturated Rubber Waste, Junpeng Wang, Zefeng Wang, Roberto Obergon, Obed Fernando
Nitroarene-Mediated Photo-Oxidative Deconstruction And Upcycling Of Unsaturated Rubber Waste, Junpeng Wang, Zefeng Wang, Roberto Obergon, Obed Fernando
University Research
Transforming waste polymers into materials with improved properties offers a compelling strategy for advancing the sustainable use of polymers, echoing the Chinese proverb: “Blue comes from indigo but surpasses it in blueness.” Herein, we report a photo-oxidative deconstruction and upcycling method for unsaturated rubber waste. Under 390 nm LED irradiation at room temperature, in the presence of a nitroarene oxidant, diverse unsaturated polymers─including natural rubber, polybutadiene, nitrile rubber, styrene–butadiene rubber, and even cross-linked nitrile gloves─are selectively converted into carbonyl-terminated oligomers. The aldehyde-functionalized products are cross-linked via dynamic imine chemistry with p-phenylenediamine to yield reprocessable elastomers with markedly improved tensile strength …