Mechanical and Thermal Performance of Interpenetrating versus Single Networks of Dynamically Crosslinked Polymers

Dynamically crosslinked polymer composites have received great attention in the past decade due to their unique properties such as self-healing, malleability, and shape memory. Dynamic crosslinkers of two main types, i.e. non-covalently bound crosslinkers and dynamic covalently bound crosslinkers, provide a versatile platform to engineer various types of crosslinked networks with desired properties.

Here, we report a combined computational and experimental study of two main categories of self-healing polymer composites: Interpenetrating Networks (IPNs) and Single Networks (SNs). We establish detailed models of the polymer networks by implementing a coarse-grained scheme: IPNs are modeled based on allowing one type of crosslinker per polymer chain, while SNs are modeled through random positioning of both types of crosslinkers along polymer chains. We then perform Non-equilibrium Molecular Dynamics simulations to evaluate mechanical and thermal properties of various IPN and SN systems. Our predictive models and experiments show that, in general, IPNs outperform SNs in terms of their mechanical and thermal properties provided that the overall crosslinker densities are the same within the two network types.