Paper Number
GN40                         My Program 

Session
Self-assemblies, Gels and Networks

Title
Viscoelasticity of model polyisoprene vitrimers

Presentation Date and Time
October 22, 2025 (Wednesday) 1:30

Track / Room
Track 2 / Sweeney Ballroom B

Authors (Click on name to view author profile)

  1. Arcangela, Russo (University of Crete)
  2. Saibal, Bhaumik (KAUST)
  3. Konstantinos, Ntetsikas (KAUST)
  4. Nikolaos, Hadjichristidis (KAUST)
  5. Benoit, Loppinet (FORTH)
  6. Vlassopoulos, Dimitris (FORTH and University of Crete, Institute of Electronic Structure and Laser)

Author and Affiliation Lines (in printed abstract book)
Russo Arcangela1, Bhaumik Saibal2, Ntetsikas Konstantinos2, Hadjichristidis Nikolaos2, Loppinet Benoit3 and Dimitris Vlassopoulos4
1University of Crete, Heraklion, Greece; 2KAUST, Thuwal, Saudi Arabia; 3FORTH, Heraklion, Greece; 4Institute of Electronic Structure and Laser, FORTH and University of Crete, Heraklion 71110, Greece

Speaker / Presenter 
Vlassopoulos, Dimitris

Keywords
experimental methods; networks; polymer melts; rheometry

Text of Abstract
Vitrimers are known to combine the desirable properties of both thermoset and thermoplastic materials. The key feature is the presence of associative dynamic covalent bonds. At high temperatures, the material becomes easily processable due to the fast kinetic rate of bond exchange reactions, while upon cooling it acquires a thermosetting behavior. Given that vitrimes often suffer from parasitic reactions following preparation, to understand their rheology and in particular the intricate interplay between bond dynamics and mechanical response, we investigate well-characterized vitrimers. They are based on polyisoprene precursors whose molar mass varies systematically from the unentangled to the well-entangled regime. We analyze the evolution of storage and loss moduli across a range of frequencies and temperatures, unraveling the unique rheological fingerprint of these materials. The vitrimer network exhibits a broad transition from elastic response to viscoelastic flow, governed by the activation of bond exchange reactions. A strong aging is observed and monitored. Lower molar masses lead to a stiffer and disordered material, whereas for higher molar masses two plateau moduli can be discerned. These results, combined with information from systematic X-ray scattering measurements support the hypothesis of cluster formation due to the microphase separation of the crosslinkers (bonding groups) in samples with lower molecular weights. We further analyze the frequency shift factors from the rheological master curves and find a transition from WLF to Arrhenious behavior which should occur at the vitrimer temperature Tv. These insights pave the way for designing vitrimers having tunable mechanical properties, with emphasis on their possible use as compatibilizers for polymer blends.