Year: 2026
Type: article
Abstract: The nonlinear viscoelastic response of telechelic metallosupramolecular polymer networks in the melt state is investigated under start-up shear and uniaxial elongation. Networks are formed from well-defined poly( n -butyl acrylate) (P n BA) star precursors with varying molecular spans (unentangled, barely entangled, and well-entangled) and metal-ligand bond strength (Zn²⁺, Cu²⁺, and mixtures). Linear viscoelastic properties are quantitatively described using the Rouse model for short stars and a tube-based time-marching algorithm for entangled stars. In start-up shear, densely crosslinked networks exhibit pronounced shear hardening, with the transient viscosity η⁺(t) increasing well above the linear viscoelastic envelope before reaching a maximum when stickers start dissociating. For these systems, a strong failure of the Cox-Merz rule is observed, in contrast to networks based on entangled precursors. In shear, the strain at the stress overshoot, 𝛾 max , is found to be independent of shear rate when sticker exchange is slow relative to deformation, indicating strain-controlled bond dissociation and an effective nonlinear sticker lifetime scaling as 𝜏 sticker,NLVE ≈ 𝛾 max /(d𝛾/dt). The maximum stretching ratio is a key parameter to rationalize transient behavior in both shear (𝜆 max ≈ 𝑁 strand 1/2 ) and elongation (𝜖 H,max ≈ ln 𝑁 strand 1/2 ). Entanglements introduce additional dissipation through chain sliding, reducing strain hardening and enhancing network toughness.
Source: Macromolecules
Institutions: UCLouvain, KU Leuven
Language: English
Subfield: Fluid Flow and Transfer Processes
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7150823267