N.K. Hansoge, Z. Liu
3M,
United States
Keywords: coarse-grained molecular dynamics, energy renormalization, rheology, adhesives
Summary:
A significant portion of 3M products are made of adhesive materials such as pressure sensitive adhesives and structural adhesives. There is a constant need to develop the capability to predict mechanical and rheological properties of these adhesive materials. Coarse-grained molecular dynamics (CG-MD) is a great tool that can be leveraged to evaluate different adhesive chemistries and predict these properties. However, obtaining precise forcefield parameters for these CG models is important to make accurate predictions. In this work, we describe a novel CG parametrization technique called the energy renormalization approach that facilitates quick and accurate parametrization of the CG models of adhesive materials. In this approach, we tune the cohesive interaction strength to match the pico-second mean square displacement value from all-atomistic (AA) simulations called the Debye-Waller factor (DWF), which has shown to be strongly connected to diffusion, relaxation time, modulus, and vibrational modes of polymeric materials. Taking one 3M adhesive as an example, we show that by matching the short-timescale DWF, we can capture the long-timescale dynamics of the polymeric system. We later use these CG models to carry out uniaxial extension and small angle oscillatory shear experiments to obtain the young’s modulus and dynamic mechanical analysis master curve respectively. We also compare these results with experimental values to show the applicability of this workflow to various adhesive materials.