Influence of Chain Stiffness on the Segmental Dynamics and Mechanical Properties of Cross-Linked Polymers

Zheng, Xiangrui; Nie, Wenjian; Guo, Yafang; Douglas, Jack F.; Xia, Wenjie

doi:10.1021/acs.macromol.3c01077

Cited by 15 publications

(2 citation statements)

References 87 publications

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“…This overall decrease in effective activation energy with disulfide bond inclusions is likely due to the increase in network flexibility as carbon linkages are replaced with disulfides. This relationship of stronger glass formation (i.e., lower E g or fragility) with more flexible networks has both experimental and simulation support. ,, The relationship between E g and T g is also shown in Figure , where a relatively linear relationship is observed (and this range of E g s and T g s would lie on the right-hand side of the cloud of polymer glass former data collected in Figure of the work by Qin and McKenna). This linear relationship makes sense for this material system, where the general cohesive energy density and reactive chemistry are held constant while the average flexibility of the network is systematically increased (by increased inclusion of disulfide linkages).…”

Section: Resultsmentioning

confidence: 67%

Glassy Dynamics of Epoxy-Amine Thermosets Containing Dynamic, Aromatic Disulfides

Lewis,

Dennis,

Park

et al. 2024

Macromolecules

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Continued progress in understanding the relaxations and mechanical performance of covalent adaptable networks (CANs) will lead to the further adoption of these unique materials across a wide range of applications. Using a model CAN system consisting of dynamic, aromatic disulfides in epoxy-amine thermosets, several network characteristics were found to vary as a function of disulfide concentration and topological placement. The mass density was found to increase significantly with the disulfide concentration, while the glass transition temperature decreased linearly with disulfide content (from 190 to 130 °C), as measured by modulated differential scanning calorimetry and dynamic mechanical analysis. Furthermore, the apparent activation energy of the glass transition, E g , as estimated by time− temperature superposition, decreased with increasing disulfide concentration. Significant changes in the sub-T g relaxations were also observed and correlate strongly with the concentration and placement of disulfide bonds within the network.

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Section: Resultsmentioning

confidence: 67%

Glassy Dynamics of Epoxy-Amine Thermosets Containing Dynamic, Aromatic Disulfides

Lewis,

Dennis,

Park

et al. 2024

Macromolecules

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“…The process employing the scCO 2 flow field is capable of producing dense wrinkles with a highly controllable wavelength in the range of 0.5–3 μm, which is highly favorable for various functional applications such as energy absorption, anticounterfeiting, self-cleaning, and catalysis. ,,− This study performs an in-depth molecular dynamic research on the motion behavior of TPU molecular chains in the scCO 2 flow field, aiming to reveal the underlying wrinkle formation mechanism. Previous studies employing fluorescence labeling techniques were limited to dilute − or semidilute systems. − Molecular dynamics (MD) simulations and nonequilibrium molecular dynamics (NEMD) simulations play a crucial role in macromolecular physics, enabling researchers to observe and analyze the behavior and interactions of polymer chains such as stretching, orientation, and twisting under shear flow at the atomic level with precision. − …”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations and Mechanistic Insights into Wrinkle Formation in TPU under Supercritical CO₂ Flow Field

Cui,

Zhou,

et al. 2024

Macromolecules

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The external force field has a profound influence on the molecular structure and properties of polymers, but the effect of the supercritical carbon dioxide (scCO 2 ) flow field on the molecular dynamics (MD) of thermoplastic polyurethane (TPU) remains uncharted. We previously discovered the formation of wrinkled structures in TPU during scCO 2 foaming in the presence of a scCO 2 flow field, but the underlying mechanism is elusive. In this work, the flow-induced orientation of TPU molecular chains and the subsequent chain relaxation when the flow field is removed are systematically investigated with nonequilibrium molecular dynamics simulations. The orientation and stretching of molecular chains intensified with an increasing shear rate (Wi), which led to increases in internal stress and kinetic energy. Although TPU chains reached similar orientation conformations under various Wi, the internal stress and orientation speed are higher in the case of high Wi. In the relaxation process, the molecular chains that are stretched at a higher Wi exhibited faster stress release and conformation disordering, which caused a smaller radius of gyration (R g ) and higher stress level compared to the initial coiled state. This fast stress relaxation behavior is believed to be responsible for the formation of fine and dense wrinkles on the TPU surface. The molecular insight from our simulations reveals the wrinkle formation mechanism and is meaningful for controlling the microstructure and properties of wrinkled TPUs.

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Enabling High Strength and Toughness Polyurethane through Disordered‐Hydrogen Bonds for Printable, Recyclable, Ultra‐Fast Responsive Capacitive Sensors

Chen,

Zhao,

Yuan

et al. 2024

Advanced Science

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The rapid advancement of smart, flexible electronic devices has paralleled a surge in electronic waste (e‐waste), exacerbating massive resource depletion and serious environmental pollution. Recyclable materials are extensively investigated to address these challenges. Herein, this study designs a unique polyurethane (SPPUs) with ultra‐high strength up to 60 MPa and toughness of 360 MJ m−3. This synthetic SPPUs can be fully recycled at room temperature by using green solvents of ethanol. Accordingly, the resultant SPPU‐Ni composites, created by mixing the ethanol‐dissolved SPPUs solution with nickel (Ni) powder, effectively combine the flexibility and recyclability of SPPUs with the electrical conductivity of the nickel filler. Notably, this work develops the printable capacitive sensors (PCBS) through transcribing the paste of SPPUs‐Ni slurry onto PET film and paper using screen‐printing technology. The devised PCBS have fast response time ≈50 ms, high resolution, and multiple signal recognition capabilities. Remarkably, SPPUs and Ni powder can be fully recycled by only dissolving the waste PCBS in ethanol. This work offers a sustainable solution to the growing e‐waste problem in recyclable flexible electronics.

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Influence of Chain Stiffness on the Segmental Dynamics and Mechanical Properties of Cross-Linked Polymers

Cited by 15 publications

References 87 publications

Glassy Dynamics of Epoxy-Amine Thermosets Containing Dynamic, Aromatic Disulfides

Glassy Dynamics of Epoxy-Amine Thermosets Containing Dynamic, Aromatic Disulfides

Molecular Dynamics Simulations and Mechanistic Insights into Wrinkle Formation in TPU under Supercritical CO₂ Flow Field

Enabling High Strength and Toughness Polyurethane through Disordered‐Hydrogen Bonds for Printable, Recyclable, Ultra‐Fast Responsive Capacitive Sensors

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Influence of Chain Stiffness on the Segmental Dynamics and Mechanical Properties of Cross-Linked Polymers

Cited by 15 publications

References 87 publications

Glassy Dynamics of Epoxy-Amine Thermosets Containing Dynamic, Aromatic Disulfides

Glassy Dynamics of Epoxy-Amine Thermosets Containing Dynamic, Aromatic Disulfides

Molecular Dynamics Simulations and Mechanistic Insights into Wrinkle Formation in TPU under Supercritical CO2 Flow Field

Enabling High Strength and Toughness Polyurethane through Disordered‐Hydrogen Bonds for Printable, Recyclable, Ultra‐Fast Responsive Capacitive Sensors

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Product

Resources

About

Molecular Dynamics Simulations and Mechanistic Insights into Wrinkle Formation in TPU under Supercritical CO₂ Flow Field