Effect of Cross Linking on Molecular Structure of Polydimethylsiloxane/Hydroxyapatite: Molecular Dynamics Simulation

The potential of nontoxic elastomers like polydimethylsiloxane (PDMS) and bioceramic hydroxyapatite (HA) crystals has been demonstrated in numerous advanced applications. However, their crosslinking behavior in a composite system has not yet been modeled through simulation. Therefore, we employed a simulation-based approach to construct initial unit cell models of PDMS and HA, and for the first time, created PDMS-HA molecular structures using Materials Studio (MS) software. Molecular dynamics (MD) methods were applied to gain deeper insight into the structural framework and physical properties of PDMS, HA, and PDMS-HA composite. Equilibrium state via Forcite, physical, chemical, and thermal properties via VAMP, and density distribution factors via MesoDyn, were determined by MD simulations employing MS software. The Forcite analysis indicated that during dynamic simulations, the kinetic and non-bond energies of PDMS and HA molecules were more stable than their potential energy, whereas the MesoDyn simulation performed much faster and efficiently. Furthermore, this study investigated the influence of PDMS-HA crosslinking mechanisms on various material properties. Energy calculations revealed that the PDMS-HA molecular structure exhibited greater stability over the examined time period compared to pure PDMS and HA. Notably, the thermal performance, particularly the entropy of PDMS-HA, improved by 93.33% and 31.82% relative to PDMS and HA, respectively.