Vitrimers are a recently developed class of polymers whose crosslinked structures grant them the mechanical properties of thermosets, while the dynamic nature of such crosslinks renders them reprocessable like thermoplastics. A major challenge of the current vitrimer field is the development of robust dynamic covalent chemistries that not only exhibit efficient associative exchange reactions, but also are scalable for industrial polymers. Toward this goal, we discovered a new siloxane exchange chemistry whose Si–O–Si bridge is thermodynamically strong, kinetically dynamic via efficient catalysis, and more hydrolytically stable than our previously reported silyl ether system. Commodity polymers such as high-density polyethylene (HDPE) and isotactic polypropylene (iPP) were converted into vitrimers by simple reactive extrusion. The resulting vitrimers demonstrate excellent creep resistance at temperatures beyond their melting transition (T<sub>m</sub>). The stress relaxation behavior and reprocessability/recyclability of the materials were also explored.  Additionally, an investigation into the siloxane crosslinks’ effect on the morphology of plastic materials is described. Collectively, we demonstrate the promise of the dynamic siloxane chemistry by converting high volume commodity polymers into recyclable, reprocessable thermosets using industrially accessible methods.

Catalyzed siloxane exchange chemistry for commodity plastic vitrimer materials

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.