Atomistic Simulations to Understand Molecular Mechanics
Chemical structure governs the bulk material properties of polymers at the macro-scale. A recently developed Accelerated ReaxFF simulation approach for kinetically slow reactions can capture thermoset polymerization. Accelerated ReaxFF simulations provide reactants with energy (comparable to the barrier energy) to form a stable transition state that, depending upon the proximity and the path of approach, leads to successful cross-linking. Accelerated cross-linking and virtual testing of the polymer can capture the translation of variable chemical structure to thermo-mechanical properties of thermosets.
Vitrimer is a new class of sustainable polymers with the ability of self-healing through rearrangement of dynamic covalent adaptive networks. However, a limited choice of constituent molecules restricts their property space, prohibiting full realization of their potential applications. Through a combination of molecular dynamics (MD) simulations and machine learning (ML), particularly a novel graph variational autoencoder (VAE) model, we establish a method for generating novel vitrimers and guide their inverse design based on desired glass transition temperature (Tg). We build the first vitrimer dataset of one million and calculate Tg on 8,424 of them by high-throughput MD simulations calibrated by a Gaussian process model. The proposed VAE employs dual graph encoders and a latent dimension overlapping scheme which allows for individual representation of multi-component vitrimers. By constructing a continuous latent space containing necessary information of vitrimers, we demonstrate high accuracy and efficiency of our framework in discovering novel vitrimers with desirable Tg beyond the training regime. The proposed vitrimers with reasonable synthesizability cover a wide range of Tg and broaden the potential widespread usage of vitrimeric materials.
Reaction path of bisphenol-F and 3,3'- Diamini diphyneylsulfone using Accelerated ReaxFF molecular dynamics simulation
Virtual mechanical testing of bisphenol F and DETDA polymer
Final structure of Laser Induced Graphene simulated from Kapton polymer using reactive molecular dynamics simulations.Â
Degradation of bis-F and diethyltoluenediamine thermoset polymer during atomic oxygen impact using ReaxFF.