Jun Wang

Partial vitrimer elastomers that combine static and dynamic covalent crosslinks provide a promising route to reconcile creep resistance with network reconfigurability; however, the mechanistic understanding of their cooperative roles under large deformation remains limited. Here, we report a high-performance silicone rubber system based on polymethylvinylsiloxane (PMVS) incorporating dynamic boronic ester bonds and static covalent crosslinks with tunable compositions. The resulting materials exhibit exceptional stretchability (>1200%) together with enhanced tensile strength and improved elastic recovery under large strains. Rheological and mechanical analyses reveal that dynamic covalent crosslinks (DCCs) enable topological rearrangement, leading to enhanced damping, extensibility, and rate-dependent response, while static covalent crosslinks (SCCs) provide a persistent elastic backbone and impose topological constraints that suppress long-time flow and delay DCC-mediated relaxation. To quantitatively describe this behavior, we develop a constitutive model that integrates non-Gaussian chain elasticity with finite extensibility, stress-assisted bond-exchange kinetics, and static-crosslink induced topological constraints. The model accurately reproduces rate- and strain-dependent mechanical behavior and enables direct partitioning of viscoelastic contributions from the static and dynamic subnetworks. This work establishes a quantitative constitutive framework linking effective bond exchange kinetics and hybrid network topology to the macroscopic nonlinear mechanics of partial vitrimer elastomers under large strains.

A simple one-step branching approach was employed to achieve simultaneous enhancement of compatibility, strength, toughness, viscoelasticity, and dimensional stability of PA6/PA66 blends through reactive extrusion. The occurrence of branching reactions and the presence of branched structures were confirmed by torque rheometer, FTIR, GPC, and rheological analysis. A selective foaming approach was adopted to investigate the effects of the modifier ADR on phase size and interfacial adhesion. The correlation between branched architecture and the mechanical properties, foamability, and creep resistance of PA6/PA66 blends was further investigated in detail. The results demonstrated that, compared to the unmodified PA6/PA66 blends, incorporation of 5.0 wt % ADR reduced the PA66 phase size from 28.0 to 7.9 μm, consequently increasing the tensile strength and tensile toughness by 18.4% and 390.6%, respectively. Furthermore, the branched structures introduced by ADR significantly enhanced both the foaming performance and dimensional stability of the blends, substantially broadening the foaming temperature window (35 °C), increasing the expansion ratio (18.2-fold), and reducing the creep strain. The branched PA6/PA66 blends also retained the toughness of branched PA6 as well as the strength and creep resistance of branched PA66. This work provides important insights for the controlled preparation and property optimization of multifunctional PA-based blends.

Rationally coupling nanoscale material design with macroscopic architecture is crucial for achieving lightweight absorbers with broadband and strong electromagnetic (EM) wave attenuation. Herein, multiscale‐engineered polyimide (PI)/MXene/Ni aerogels integrating magnetic Ni nanochains, dielectric MXene sheets, and anisotropic porous architectures are reported. Ni nanochains with controlled morphology were synthesized via NaOH‐assisted hydrazine reduction, while directional freezing enabled the fabrication of random, parallel, and normal aerogel architectures. The normal‐aligned PI/MXene/Ni aerogel exhibits a remarkable minimum reflection loss (RL _min ) of −72.42 dB at 2.8 mm. Guided by a genetic‐algorithm optimization, tri‐layer assemblies further expand the effective absorption bandwidth (EAB) to 8.4 GHz while maintaining an outstanding RL _min of −61.69 dB. The superior absorption originates from synergistic dielectric–magnetic–structural losses, including interfacial polarization, ohmic/eddy‐current dissipation, and gradient impedance matching enabled by the layered porous framework. Beyond EM attenuation, the aerogels feature ultralow density, high compressive strength, enhanced hydrophobicity, intrinsic flame retardancy, and low thermal conductivity, providing effective infrared stealth and thermal protection. This work demonstrates a multiscale design strategy to create multifunctional, broadband EM absorbers for demanding electronic and aerospace environments.

Polyethylene terephthalate (PET) hydrolysis by Ideonella sakaiensis PETase (IsPETase) begins at a heterogeneous solid–liquid interface, yet the molecular basis of productive surface recognition remains poorly resolved. Here, we combined a Martini 3 coarse-grained PET model with Go̅Martini protein dynamics to investigate IsPETase binding to an extended PET surface. A four-state kinetic model, comprising unbound, encounter, docked, and precatalytic states, shows that productive binding is not limited by adsorption itself but by a postadsorption reregistration step that converts surface-bound encounter complexes into productively aligned configurations. The simulations reveal a stage-dependent role of conformational flexibility: flexible surface loops facilitate early capture, whereas excessive flexibility promotes misregistered hydrophobic contacts, overstabilizes nonproductive encounter states, and lowers the overall probability of productive commitment. Route analysis on the contact landscape further shows that successful trajectories either commit directly to a product-like basin or undergo reregistration through encounter/transition basins. Comparative simulations of engineered PETase variants uncover a flexibility-driven speed–yield trade-off in which increased flexibility accelerates successful binding events but reduces productive yield through encounter-state over-anchoring. Guided by this mechanism, we formulated a landscape-based design strategy that either weakens encounter-specific anchors or reinforces product-like contacts, leading to mutations that improve productive-binding yield. These results identify postadsorption alignment as the key kinetic bottleneck in PETase surface recognition and provide a mechanistic framework for designing enzymes that operate at heterogeneous polymer interfaces.

Encapsulation d'huile de DHA sous forme d'émulsion de Pickering : effet sur la bioaccessibilité et le métabolisme du DHA: L'encapsulation peut affecter la digestion et la bioaccessibilité des composés encapsulés, ce qui peut ensuite affecter leur métabolisme. Le but de ce projet était d'étudier les effets de l'encapsulation sur la bioaccessibilité et le métabolisme du DHA, en étudiant une huile de DHA non-encapsulée ou encapsulée, apportée sous forme d'omelette comme matrice alimentaire.L'huile de DHA, composée de triacylglycérols riches en DHA, a été préparée sous forme d'émulsion de Pickering, stabilisée par des isolats de protéines de lactosérum dénaturés par la chaleur. De l'huile pure ou sous forme d’émulsion a ensuite été ajoutée à l’œuf liquide pour obtenir de l’omelette. Les effets de l'encapsulation sur la digestion ont été étudiés à l'aide d'un modèle de digestion statique in vitro pour adulte, puis l’impact sur le métabolisme du DHA a été mesuré sur un modèle rat pris au sevrage.Les résultats ont montré in vitro que l'encapsulation peut augmenter la surface de contact entre l'huile de DHA et les enzymes de digestion, favorisant l'hydrolyse lipasique de l’huile de DHA et améliorant ainsi la bioaccessibilité du DHA. In vivo, l'encapsulation n'a pas impacté le profil global des acides gras, et particulièrement l’accrétion du DHA dans le cerveau. En revanche, le profil des oxylipines, dérivés oxydatifs d’acides gras, a été fortement modifié dans le plasma, le cœur et même le cerveau. Les métabolites dérivés du DHA ont globalement été augmentés tandis que ceux issus des acides gras de la famille n-6 ont été essentiellement atténués.Par conséquent, l'encapsulation de l'huile de DHA pourrait non seulement améliorer la bioaccessibilité du DHA, mais constitue également un facteur clé dans le métabolisme du DHA pour produire des précurseurs de protectines et de maresines, améliorant ainsi le statut de santé global.

Achieving simultaneously high-efficiency shielding effectiveness (SE) and ultralow reflection coefficient remains challenging for next-generation electromagnetic interference (EMI) shielding materials. In this work, we report rationally designed three-layer architectures comprising a low-reflection polyvinylidene fluoride (PVDF) foam layer, a carbon nanotube (CNT)/flaky Fe/PVDF composite foam as the absorption layer with tuned impedance matching and attenuation characteristics, and a thin graphene film as the reflective shielding layer to promote reflection–reabsorption cycles. Gradient and asymmetric sandwich configurations are designed based on intrinsic reflectance (Rη) considerations. With a total thickness of ~2 mm, the optimized multilayer structures achieve an ultrahigh EMI SE of up to 118 dB. Through systematic variation of layer sequence and thickness, distinct attenuation behaviors are revealed. Gradient structures enable progressive impedance transition and reduced overall reflection, achieving a low average reflection coefficient of 0.052 in the X-band. In contrast, asymmetric sandwich architectures enhance internal dissipation through multiple reflections and phase-dependent interference, yielding ultralow reflection at selected frequencies with a minimum reflection coefficient as low as 0.0001 and a corresponding ultrahigh absorption-to-reflection ratio (A/R) of 9962. Transmission-line theoretical predictions and CST simulations agree closely with experimental results, indicating that the reflection behavior is predominantly governed by impedance recursion and thickness-dependent phase interference, with higher-order microstructural effects implicitly accounted for through effective electromagnetic parameters. This work establishes a fundamental framework for rationally designing absorption-dominant multilayer EMI shielding systems through coordinated regulation of electromagnetic properties, impedance characteristics, and phase-controlled thickness optimization.