The polymer possessing with planar structure can be activated and guided to encapsulate the inner space of SWNT and form a helix through van der Waals interaction and the π-π stacking effect between the polymer and the inner surface of SWNT. The SWNT size, the nanostructure and flexibility of polymer chain are all determine the final structures. The basic interaction between the polymer and the nanotubes is investigated, and the condition and mechanism of the helix-forming are explained particularly. Hybrid polymers improve the ability of the helix formation. This study provides scientific basis for fabricating helical polymers encapsulated in SWNTs and eventually on their applications in various areas.

Novel scroll peapods are fabricated simply by utilizing the spontaneous scrolling mechanism of graphene onto fullerene string. The basic interaction between the graphene and the fullerene string is investigated, and the mechanism of the formation of the scroll peapod is explained in particular. The formation of the scroll peapod and its formation time are influenced by the combined effects of fullerene number, diameter and graphene size. It is also worth noting that narrow graphene nanoribbon wrapped onto a C720 bean can form a particular helical peapod. Higher temperature slows the scrolling dynamics, and even hinders the formation of the scroll peapod. This study provides a scientific basis for producing scroll peapods simply, and eventually their applications in various areas.

Molecular dynamics simulations demonstrate that several polyacetylene (PA) chains can encapsulate and self-assemble into multi-stranded helical structures in confined inner space of carbon nanotubes (SWCNTs). The driving van der Waals force and curvature provided by the tube wall enable polymers to bend and spiral to maximize the π-π stacking area with the tube wall when filling the inside of the SWCNT. Structural forms and knitting patterns of multiple helices are influenced by the combined effect of the tube space, the number of PA chains and the temperature. The knitting pattern of a six-helix is unique and a knitted six-helix can exist steadily after removing the SWCNT while a two- to five-helix will recover intrinsic straight configurations.

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Helical nanomaterials represent an emerging group of nanostructures because of their multiple functionalities enabled by unique spiral geometry and nanoscale dimensions. This study demonstrates that several trans-transoid polyacetylene (Tt-PA) chains can self-spiral limitlessly over the whole length of polymers to form regular multiple helices under the inducement of water cluster, fullerene ball and metallic nanoparticles (NPs). Multi-helices possess random chirality selection which have equal probability of left-handedness and right-handedness. Energy components, geometric parameters and differences of helices induced by different NPs are analyzed to deeply probe the possible mechanism and the nature of the limitless spiral of the PA polymer. Furthermore, the helical self-assembly of cis-formed cis-transoid (Ct-PA) and transcisoid (Tc-PA) isomers is further studied. The spiral ability of Ct-PA is much higher, but Tc-PA is much lower than that of Tt-PA. Remarkably, Tc-PAs are always form five-helix at room temperature.