Ultrahigh energy-density flexible dielectric films achieved by self-bundled polymer nanocluster in necklace-like arrangement

Flexible dielectric materials with ultrahigh energy density (Ue) is of critical importance to reduce the size of dielectric capacitors, which has recently drawn ever-increasing attention. Herein, different from the incorporation of traditional 1D/2D inorganic nanofiller into single/multi-layer polymer matrix, a multifunctional poly (p-phenylene terephthalamide) (PPTA)-based derivative fluxible polymer (f-PPTA) nanocluster is selected and introduced to typical ferroelectric poly (vinylidene fluoride) (PVDF) matrix. As a novel polymer-based nanofiller, the f-PPTA nanocluster consists of self-bundled parallel sulfonated PPTA skeleton and grafted with octadecylamine polyoxyethylene ether amphiphilic (PEGO) amine ligand through ionic interaction. In the multi-arm amphiphilic PEGO, one alkyl chain with the length of 15 carbon atoms provides similar hydrophobic nature to that of PVDF, which contributes to improving the interfacial compatibility between polymer nanocluster and matrix. Furthermore, the relatively short hydrophilic chain with the length of 8 carbon atoms induces a specific necklace-like arrangement of the f-PPTA nanoclusters in PVDF matrix during film fabrication spontaneously. Consequently, an ultrahigh Ue ~ 22.5 J•cm−3 of the dielectric film is acquired at 600 MV•m−1 electric field. This value is the highest reported so far among all the poly (vinylidene fluoride) (PVDF)-based dielectric nanocomposites to the best of our knowledge. In addition, the elongation at break of the film can be increased to 390%, which is over 9 times that of pure PVDF sample. This work provides a new route to PVDF-based polymer nanocomposites with ultrahigh Ue and highly stretchable performance.