Micromechanics of PS/PB/PS Triblock-Copolymer Films with Lamellar Morphology

Abstract

ABSTRACTHighly oriented, near single-crystal lamellar triblock copolymer films with alternating rubbery-glassy layer morphology possess an interesting anisotropy in their mechanical behavior, which can prove to be attractive for various applications. Here, the deformation micromechanics of highly oriented styrene-butadiene-styrene (SBS) lamellar triblock copolymers are investigated. The competing roles of the glassy (PS) and rubbery (PB) phases in the layered configuration are studied with micromechanical finite element based representative volume element (RVE) models subjected to tensile loading at different directions to the lamellar plane. The calculated material response is compared to x-ray and microscopy data from the literature, and proves to be successful in linking the macroscopic material response to the underlying physics of the microstructural evolution. Moreover, the RVE simulations are successful in reproducing the mechanical behavior of highly oriented nano-clay block copolymer nanocomposites. The response of layered-silicate models having 2wt% clay content is compared to the behavior of the respective neat block copolymer (BCP) and to existing experimental data. The ultimate objective is to facilitate these micromechanical models to design hierarchically ordered materials with properties, which will be optimally tailored for different classes of applications.