Séminaire PMMH, Joshua Dijksman (UVA)

Covalent adaptable polymer networks provide mechanical tunability via molecular and mesoscopic lengthscales

Polymeric materials are ubiquitous in society but also present a large source of waste. There is an ongoing search for polymeric materials that can be better tuned and recycled. One class of polymers that came into the spotlight for this purpose are so-called covalent adaptable polymer networks. Such polymer networks are dynamic due to the reversible nature of some of the bonds. We demonstrate that fine-grained, quantitative control over macroscopic dynamic material properties can be achieved in such materials using the Hammett equation that controls the strength of the dynamic bonds. Moreover, we reveal with Raman spectroscopy that mesoscopic phase separation occurs in these materials. The phase separation can be controlled via concentration and molecular design. The mechanisms of phase separation in dynamic polymer networks are particularly interesting as the reversible nature of the network participates in the structuring of the micro- and macromolecular domains, for which theoretical development is still largely incomplete.