CAS: Reprocessable Thermosets for High Performance Composites

Polymer matrix composites (PMCs) are an important class of lightweight structural materials used in applications relevant to sustainable energy production and use, with examples including electric vehicles and wind turbines. Traditional epoxy resins used as matrix materials for PMCs are inherently non-recyclable, however. One solution to this problem is to take advantage of recent advances in the development of covalent adaptive networks with dynamic bonds that are able to break and reform at a rate that depends on the temperature. Polymeric materials with dynamic bonds as crosslinks can be repaired after fracture or completely recycled, a capability that has led to the development of a large range of sustainable materials. The nature of these dynamic crosslinks is commonly assessed above the glass transition temperature, where the dynamic nature of the crosslinks leads to a well-defined relaxation time of the elastomeric material. The proposed project is based on the hypothesis that dynamic bonds will also impact the nature of yield and fracture in the glassy polymer regime. A corollary to this hypothesis is that when appropriately understood, incorporation of dynamic bonds in a glassy polymer network can lead to the development of rigid, glassy materials with toughness exceeding values obtained with existing materials. The dynamic nature of the network also enables more efficient processing routes for on-demand manufacturing and repair of materials with complex geometries.