Single-walled carbon nanotube nanoring induces polymer crystallization at liquid/liquid interface

Polymer crystallization confined at liquid/liquid (L/L) interface has attracted increasing attention during the past decade. In this study, we show that single-walled carbon nanotubes (SWCNTs) can be bent into ring-shaped structure via a Pickering emulsion method. These SWCNT rings are pinned at L/L interface of nanosized oil droplets suspended in water. When dilute crystalline polymer solution was used as the oil phase, upon cooling, these polymers crystallize onto the SWCNT nanorings. This system thus provides a unique platform to investigate heterogeneous nucleation and crystal growth at L/L interface. Polyethylene, poly(l-lactic acid), and poly(3-hexylthiophene) are used as the crystalline homopolymers. Our results show that heterogeneous nucleation dominates the crystallization process, and nano hybrid shish kebab nanorings have been formed. Despite small diameters of the rings, the previously reported soft epitaxy mechanism still holds. Polyethylene-b-poly(ethylene oxide) has also been patterned onto the SWCNT nanorings, leading to hierarchically ordered nanostructures. The block copolymer-decorated SWCNTs have been used to direct nanoparticle assembly. Our work therefore shows a promising means to produce complex, hierarchical, and functional hybrid materials.