Coupled Effects of Crosslink Density, Chain Length, and Dynamic Bond Exchange in Covalent Adaptable Networks

In covalent adaptable networks (CANs), strand molecular weight and crosslink density are intrinsically coupled through the network architecture, yet their combined influence on network topology and dynamic behavior has not been systematically quantified at the molecular level. Here, atomistic molecular dynamics simulations are performed on amine-ester-based CANs with systematically varied strand length and crosslink density to quantify their coupled effects on network topology and dynamic characteristics. A nonmonotonic dependence on strand length is consistently observed, arising from the combined influence of chemical crosslinking and topological constraints. Topological constraints from primitive path analysis also show distinct spatial distributions with respect to crosslink points. Additionally, the residual stress ratio between systems with and without dynamic bond exchange exhibits an approximately linear relationship with the kink number, suggesting that the stress associated with permanent network connectivity is relaxed more efficiently than stress arising from topological constraints. These findings provide a comprehensive molecular understanding of the coupled structure–property relationships in CANs and demonstrate that network topology should be considered together with bond exchange chemistry in the molecular design of adaptable polymer networks.