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In this study, the early stage of interfacial crystallisation behaviour of low molecular weight polyethylene (PE) and isotactic polypropylene (iPP) oligomer on the surface of carbon nanotubes (CNTs) with different diameters, chiralities and topography structures was studied using MD simulations. We started to simulate the effect of CNTs chirality and diameter on PE molecular chain orientation, and then the effect of CNTs topography structure on PE and iPP molecular chain orientation was investigated. Finally, some experiments were carried out to prove the simulated results. Our study shows that for CNTs with a diameter comparable with the radius of gyration (Rg) of a polymer chain, an easy orientation of PE chains along CNTs axis is observed for all the systems of the CNTs with different chiralities due to a geometric confinement effect. For CNTs with a much larger diameter, multiple orientation of PE chains is induced on its surface due to the lattice matching between graphite lattice and PE molecular chains. In this case, the chirality of CNTs dominates the orientation of graphite lattice, which determines the orientation of PE chains arrangement on CNTs surface. More importantly, it was found that the groove structure formed by CNT bundles is very useful for the stabilisation of polymer chain, and thus facilitates the orientation of molecular chain along the long axis of CNTs. As a result, a novel nanohybrid shish–kebab (NHSK) structure with CNTs acting as central shish while polymer lamellae as kebab can be successfully obtained for both PE with zigzag conformation and iPP with helical conformation. This simulation result was well supported by the experimental observation. Our study could provide not only a deep understanding of the origin of the polymer chain orientation on CNTs surface but also the guidance for the preparation of polymer/CNTs nanocomposites with novel NHSK structure. [ABSTRACT FROM PUBLISHER]

Nanohybrid shish kebab (NHSK) structure, in which fibrous carbon nanotubes (CNTs) act as shish, while polymer lamellae as kebab, is of particular interest both scientifically and technologically. In this work, two types of CNTs with the same diameter range and different topography structure, namely multiwalled carbon nanotubes (MWNTs) with a relatively smooth surface and double-walled carbon nanotubes (DWNTs) bundles with a groove structure, were used to induce polyethylene (PE) crystallization for the formation of NHSK. For PE/MWNTs system, NHSK was formed only at a relatively low crystallization temperature (Tc), and PE lamellae are not completely perpendicular to the long axis of MWNTs. However, for PE/DWNTs bundles system, NHSK could be obtained even at a much higher Tc, and almost all the PE lamellae are perpendicular to CNTs long axis, due to the unique "groove structure" formed by DWNTs bundles. The enhanced nucleation ability and the facilitated lamellae orientation by using DWNTs bundles are not only of great crystallography interest but also are very important for functional design in nanodevice applications. [ABSTRACT FROM AUTHOR]

Nanohybrid shish kebab (NHSK) structure, in which fibrous carbon nanotubes (CNTs) act as shish, while polymer lamellae as kebab, is of particular interest both scientifically and technologically. In this work, two types of CNTs with the same diameter range and different topography structure, namely multiwalled carbon nanotubes (MWNTs) with a relatively smooth surface and double-walled carbon nanotubes (DWNTs) bundles with a groove structure, were used to induce polyethylene (PE) crystallization for the formation of NHSK. For PE/MWNTs system, NHSK was formed only at a relatively low crystallization temperature (Tc), and PE lamellae are not completely perpendicular to the long axis of MWNTs. However, for PE/DWNTs bundles system, NHSK could be obtained even at a much higher Tc, and almost all the PE lamellae are perpendicular to CNTs long axis, due to the unique “groove structure” formed by DWNTs bundles. The enhanced nucleation ability and the facilitated lamellae orientation by using DWNTs bundles are not only of great crystallography interest but also are very important for functional design in nanodevice applications. [ABSTRACT FROM PUBLISHER]