Mechanical performance of the polymer-inorganic interfaces: Molecular mechanisms and modes of failure
SJ Wang and M Zhang and J Feng and ZP Xu, MECHANICS OF MATERIALS, 175, 104479 (2022).
Composites combining the polymer and inorganic phases are ubiquitous in nature and the industry. The relationship between interfacial molecular structures and their mechanical performance is a critical issue to be addressed in practical applications. Structural and mechanical properties of the polymer-inorganic interfaces are investigated by molecular dynamics simulations in this work. Representative material systems are constructed, consisting of compliant polymer films (ultraviolet-light adhesives, polymethyl methacrylate) and brittle inorganic substrates (Si, SiO2, ZrO2). The conformational characteristics of polymer chains near the inorganic surface shows a distinct contrast with that of bulk polymers. Interfacial strength and toughness are calculated from the simulations. We elucidate the underlying molecular mechanisms and report the material parameters that can be used in continuum models such as the cohesive zone models and assessed by experimental tests. The results allow us to predict the modes of failure, which are determined by the competition between cohesion in the polymer phases and adhesion at the polymer-inorganic interface. In addition, modifying the polymers and interfaces through the molecular weight, crosslink and surface charges is proposed as practical approaches to engineer the mechanical performance of the polymer-inorganic composites.
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