Coarse-Grained Molecular Dynamics Study of Styrene-block-isoprene-block-styrene Thermoplastic Elastomer Blends

Styrene-block-isoprene-block-styrene (SIS) triblock copolymers induce characteristic physical properties and domain morphologies when blended with different types of styrene copolymers. The domain morphology of two types of polymer blends, a binary symmetric/asymmetric SIS copolymer (SIS/aSIS) and a binary symmetric/symmetric SIS copolymer (SIS/sSIS) with different molecular weights, was investigated by both atomic force microscopy-based nanomechanical mapping and coarse-grained molecular dynamics simulations. In the simulations, optimal settings of the nonbonding interaction potentials were determined to help reproduce the experimentally observed properties; using those potentials, uniaxial elongation simulations were performed. Furthermore, the correlation between structures and mechanical properties under uniaxial elongation was studied. The structural factors affecting the magnitude of the stress were considerably different between the SIS/aSIS and SIS/sSIS models and changed depending on the strain.