Control of Polymer Crystallization by Pseudo-Polyrotaxane Nanosheets

We present a straightforward yet highly efficient approach for controlling the orientations of poly(ethylene oxide) (PEO) lamellae by introducing pseudopolyrotaxane nanosheets (PPRNSs), a novel class of two-dimensional fillers featuring well-organized polymer brushes. Grazing-incidence wide-angle X-ray scattering reveals parallel alignments of uniformly flat-on PEO lamellae to the film surface, and the degrees of their orientations are closely linked to the PPRNS concentration. Via control experiments and comprehensive investigations of crystallization kinetics and morphological evolutions of nanocomposites with different PPRNS contents, we elucidate the mechanism driving lamellar orientation. PPRNSs provide additional nucleation sites for PEO crystallization, thereby influencing the crystallization kinetics. PPRNSs, acting as nucleating agents, accelerate crystallization rates, impacting crystal morphology, crystal growth direction, and crystallinity preservation. Control experiments emphasize the distinct roles of polymer brushes in offering nucleation sites. This study lays the foundation for diverse applications and further explorations of PPRNS-based materials in the fields of polymer nanocomposites, surface engineering, and functional material design.