Elasticity and Dynamics of Elastomeric Epoxy Networks: Comparing Simulations and Experiments at High Frequency

This study investigates the elastic and dynamic properties of elastomeric, stoichiometric epoxy networks formed between the telechelic functionalized poly(ethylene glycol) diglycidyl ether (PEGDE) and the linear cross-linker 1,4-diaminobutane across a range of extensional strain rates (10⁷ to 10¹⁰ s^-1), molar masses (n = 3, 5, 8 repeat units), and two reaction extents determining degree of cross-linking through atomistic simulations and compares them with the experimental n = 8 system. Investigated properties are Young's and shear moduli, the C₁₁ elastic constant, the glass transition temperature, and the network's mean-squared-displacement. Results reveal a notable agreement between simulation-obtained and experimental values of C₁₁ and its experimentally determined Brillouin light scattering (BLS) value and glass transition temperatures, bridging the gap between atomistic and macroscopic length scales. This work contributes to the renewed interest of BLS applied on soft systems and lays the groundwork for computational investigations of complex epoxy architectures, such as dual networks with epoxy covalent and noncovalent bonds.