Improving the Thermomechanical Properties and Processability of Elastomeric Vitrimers Using Thermoreversible Organic Nanofillers

Vitrimers are a promising class of polymer networks that feature thermally activated dynamic covalent bonds. Although promising for many applications in material science, vitrimers tend to be difficult to process because of high viscosity. Processability is commonly enhanced at the expense of mechanical performance at service temperature, and thus this trade-off remains an important challenge in the development of these materials. Herein, we report a new approach based on thermoreversible organic nanofillers (TRONs), which we define as low molar mass molecules that act as reinforcing fillers at the service temperature and plasticizers at the processing temperature. This concept is exemplified in the context of an elastomeric dioxaborolane-based polybutadiene vitrimer as a model matrix, and two different dibenzylidene sorbitol derivatives are evaluated as TRONs. We find that vitrimers loaded with TRONs exhibit improved creep resistance and tensile properties at service temperatures while also exhibiting lower viscosity at processing temperatures.