Integrated Simulation System for Soft Materials.

It may be possible to use a simplified chemical reaction model to create a complex three dimensional network structure when using molecular dynamics to study cross linked structure of thermoset plastics. However, the molecular weight required for such a reaction process would be so large that it would require a long calculation time to relax the entire system structure.

It is therefore recommended to use coarse-grained molecular dynamics to create the cross linked structure from the reaction process, and then apply reverse mapping to the full atomistic model after thoroughly relaxing the system.^[1]

In order to create the coarse-grained model for the reverse mapping, it is necessary to generate a potential parameter value reflecting the molecular chemical properties. To solve this problem, we used the J-OCTA COGNAC modeler to obtain the coarse-grained potential of an epoxy monomer before and after a reaction along with a hardening agent. We then performed a reaction calculation using coarse-grained molecular dynamics to create a cross linked structure of epoxy resin (Figure 1).

As shown in Figure 2, the density of a mixed system with the pre-reaction monomer plus the hardening agent was 0.91 [g/cm3]. After the reaction, the density increased to 1.28 [g/cm3].

We are currently working on easier way to apply reverse mapping to the full atomistic model.