(200b) Understanding Relationships Between Molecular Structures and Thermomechanical Properties of Thermosetting Polymers with Novel Bio-Based Building Blocks

Thermosetting polymeric materials are widely used in protective coatings and structural applications. Many thermal and mechanical properties of thermosetting polymers are related to their specific monomer molecular structures and random network architectures. Although properties of thermosetting materials can be obtained experimentally, an ability to predict properties of new materials based on molecular structure will significantly facilitate new thermosetting material design. In this work, we use computer simulations to investigate the structure and the properties of thermosetting materials based on novel bio-based building blocks. Molecular dynamics simulations and experiments are used to study highly cross-linked epoxy networks comprised of a furanyl epoxy monomer, 2,5-bis[(2-oxiranylmethoxy)methyl]-furan (BOF), that is cross-linked by two furanyl amine hardeners, 5,5â?²-methylenedifurfurylamine (DFDA) and 5,5â?²-ethylidenedifurfirylamine (CH3-DFDA). A general constant-NPT MD procedure is used to identify the glass transition temperature (Tg) of the cross-linked polymers with two versions of general AMBER force field (GAFF) for parameters: one with original GAFF parameters and one with refitted dihedral parameters for specific parts. Important properties of these four systems including density and Tg are compared with experimental results. We also compare the simulated and experimental values for fully furan-based thermosetting materials to those using the conventional resin diglycidyl ether of bisphenol A (DGEBA) cured with the two furanly hardeners. Predicted Tg overpredicts experimental results but captures experimental trends between different epoxies and amines very well. Finally we analyze the effect of epoxy/amine monomer on Tg through microscopic details of the structures and flexibility of the polymer chains.