Linear Rheology of Immiscible Polydimethylsiloxane/Polybutadiene Vitrimer Blends

Polymer blending offers a cost-effective approach to tailoring material properties for industrial applications. However, the inherent incompatibility between polymers often results in poor interfacial adhesion, necessitating the use of compatibilizers. Vitrimers are networks cross-linked through dynamic covalent chemistry, which undergo molecular network rearrangement via associative exchange. By incorporating vitrimer chemistry, a polymer gains enhanced chemical and physical durability, maintains processability through stress relaxation and flow, and improved interfacial adhesion with other materials. Consequently, it offers an alternative compatibilization method for immiscible polymer blends. In this talk, we consider polydimethylsiloxane (PDMS) and polybutadiene (PB) blends containing dioxaborolane cross-links that undergo associative exchange. PB weight percent and cross-link density were systematically varied. Linear rheology measurements indicated two relaxation regimes: fast and slow. The fast regime – associated with segmental motions – is governed by PB weight percent, whereas the slow regime is independent of PB weight percent and follows time-temperature and time-composition superposition. Potential mechanisms governing the linear rheology are discussed.