Modulation of Depolymerizable Poly(thioether-thioester) Properties in Reversible Covalent Composites

We incorporated thiol-functionalized silica particles as macroinitiators for the construction of composites by ring-opening polymerization of thiolactones. A separate photochemical cross-linking step was employed to enhance the stability of the polymer composite material. The thermal and mechanical properties of the materials can be tuned by varying the amount of particles, and a representative formulation could be 3D printed. The polymer composite was depolymerized in the presence of a catalytic amount of thiol and 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) base to recover substantial amounts of monomer, which were repolymerized and photo-cross-linked to give a material very similar in mechanical properties to the virgin composite. The modular nature of this system and the reliability of the bond-forming and bond-breaking steps suggest that it may prove to be useful as a new type of recyclable plastic.