2025 Student Poster Prize - 3rd Place

Viscoelasticity and extensional rheology of polystyrene vitrimers

1. Guarino, Teresiana (FORTH, Institute of Electronic Structure and Laser)
2. Russo, Arcangela (FORTH, Polymer and Colloids)
3. Mavromanolakis, Antonis (FORTH)
4. Conti, Matteo (ESPCI, Chimie Moléculaire, Macromoléculaire, Matériaux)
5. Van Zee, Nathan (ESPCI)
6. Nicolay, Renaud (ESPCI)
7. Coppola, Salvatore (Versalis s.p.a.)
8. Vlassopoulos, Dimitris (FORTH and University of Crete, Institute of Electronic Structure and Laser)

Abstract

A formidable challenge in soft matter is to develop materials that combine the reprocessing capabilities of thermoplastics with the shape stability and mechanical strength of thermosets. Most approaches aim to create crosslinked networks with dynamic covalent bonds, which can reversibly form and break in response to changes in external conditions. Materials containing these dynamic covalent bonds are referred to as Covalent Adaptable Networks (CANs). A specific subset of CANs, known as vitrimers, was introduced by Leibler and colleagues in 2011. Vitrimers exhibit two key characteristics: they maintain stable network connectivity across a range of temperatures and can relieve mechanical stresses through bond exchange reactions. In this work, we present our current results on the linear and extensional rheology of a series of polystyrene vitrimers, where dynamic exchange reactions are facilitated by dioxaborolane metathesis. We show how crosslink density and dynamic bond exchange influence the flow and deformation behavior under both linear and nonlinear deformations, which are particularly relevant for processing operations. In particular, a systematic investigation of the uniaxial extensional response of vitrimer systems is presented, detailing how the presence of dynamic crosslinkers affects strain hardening behavior. We also provide preliminary data on biaxial extension. These insights contribute to a deeper understanding of the fundamental rheological behavior of polystyrene-based vitrimers and their potential for use in advanced material design.

3^rd Place, 96^th Annual Meeting, Oct 2025, Santa Fe