Nanoparticles induced limitless spiral of polyacetylene isomers.

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 trans-cisoid (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.