Atomistic insights into the toughening role of surface-treated boron nitride nanosheets in PLA-based nanocomposites

Abstract

The poor toughness of polylactic acid (PLA) has led to imposing certain restrictions on its use in various applications. In similar cases, introducing nanostructures is known to be a practical strategy for tailoring the mechanical features of polymeric materials. Herein, the contributory impacts of the presence of pristine and surface-treated boron nitride nanosheets on the mechanical behavior of PLA were explored through molecular dynamics simulations. Comparatively, it was observed that embedding 3 wt% untreated boron nitride nanosheet (BNNS) improved Young’s modulus and toughness of the polymer by 24.5% and 42%, respectively. Both chemical and physical surface treatments resulted in significantly lower polymer chains mobility during the deformation by intensifying interfacial interactions. Moreover, the obtained findings illustrated that applying either of chemical hydroxyl functional groups or PLA chains onto BNNS would contribute to the enhancement of PLA toughness. Among all the analyzed systems, approximately 5% functionalized nanosheets indicated the best toughening role by increasing PLA absorbed energy per unit volume by 131% on average although the enhancing role of chemically functionalized nanofiller was slightly better. The present findings could give a deeper insight into obtaining more efficacious designs for tailoring mechanical properties of polymer-based nanocomposites.