Polyethylene‐Assisted Exfoliation of Hexagonal Boron Nitride in Composite Fibers: A Combined Experimental and Computational Study. Issue 8 (14th February 2015) - Meng, Jiangsha
Abstract A joint experimental and computational approach is used to explore the exfoliation mechanism for hexagonal boron nitride (h‐BN) in polyethylene (PE)/h‐BN composite fibers during hot‐drawing. A shear‐flow gel‐spinning apparatus is utilized to fabricate PE/h‐BN composite fibers with 11 wt% h‐BN loading. Different exfoliation states of the h‐BN platelets before and after hot‐drawing are experimentally examined using wide‐angle X‐ray diffraction and Raman spectroscopy. Compared with the undrawn (as‐spun) fibers, both analyses show that the intensity of the major h‐BN peaks attributed to interlayer interaction significantly decreased for the drawn fibers, suggesting exfoliation of the h‐BN. A full atomistic steered molecular dynamics approach is used to obtain baseline force and work required for h‐BN layer separation, as well as to simulate the h‐BN exfoliation behavior as a result of the PE matrix shearing effect in the composite. Computational results indicate that a large interactive area between the polymer and the fillers is required to induce enough stress transfer to exceed the h‐BN exfoliation force/energy threshold. Once this threshold is achieved, complete exfoliation of the platelets to monolayer h‐BN is demonstrated. By understanding the relationship between interfacial area and interaction strength between polymer matrix and fillers, this work provides new insight toward use of polymers for producing mono‐ and few‐layered h‐BN.