Quantum chemistry study of the interaction between ionic liquid-functionalized TiO₂ quantum dots and methacrylate...

Quantum Chemistry calculations within the density functional Theory (DFT) are a powerful feature to obtain the atomistic and molecular properties of macromolecules such as polymers and nanoparticles. DFT calculations are essential to understand the stability of new composite materials. In this work, DFT with the Local Density Approximation (LDA) and norm-conserving pseudopotentials is used to analyze the energetic stability as well the electronic properties when titanium dioxide quantum dots (TiO_2QDs) are added to an adhesive resin (methacrylate - HEMA - and dimethacrylate - BisGMA - monomers), which presents reliable physical, chemical, and biological properties in dentistry. The ionic liquid 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF₄) was previously used to functionalize the quantum dots, forming the complex system TiO₂QDs/BMI.BF₄. DFT provides the most stable configuration through binding energies and bond distances analysis. Our results show that van der Waals interactions between BisGMA and HEMA may contribute to the stabilization of the interaction between the resin and TiO₂QDs/BMI.BF₄. Furthermore, according to experimental results, the calculations show that the presence of the ionic liquid increases the quantum dots and resin interactions (binding energies), suggesting that the ionic liquid is important to stabilize the TiO₂QDs/BMI.BF₄-resin composite.