Control on Viscoelasticity of Recyclable Elastomer via Orthogonal Dynamic Bonds to Realize Extrusion Reprocessing

The recycling of elastomers presents significant challenges, primarily due to the constraints of continuous processing technologies. Though dynamic chemistries have been employed to create dynamic cross-linked structures in elastomers, thereby guaranteeing their recyclability, these materials cannot be reprocessed in a continuous manner that is conducive to industrial applications. The processability of polymers is largely determined by their viscoelasticity, fluidity, and other rheological properties. This study investigates the incorporation of orthogonal dynamic bonds in both associated (imine) and dissociated (anthracene dimerization) mechanisms within a single system to effectively regulate the viscoelasticity and fluidity of the elastomer, making it amenable to extrusion processing. The integration of orthogonal dynamic bonds results in a semisolid state with a viscosity ranging from approximately 10³ to 10⁴ Pa·s, providing controllable fluidity within the temperature range of 160–180 °C, which facilitates continuous extrusion processing. The dimerization of anthracene necessitates UV light to initiate, thereby allowing for the differentiation of reaction conditions for both mechanisms, which also enhances the properties of the reprocessed products. Consequently, the orthogonal dynamic bonds can effectively modulate the viscoelasticity of the recyclable elastomer, enabling the implementation of continuous processing technologies and providing potential for 3D printing.