Freeze-drying and hot-pressing strategy to embed two-dimensional Ti_0.87O₂ monolayers in commercial polypropylene films with enhanced dielectric properties

The dielectric capacitor has been widely used in advanced electronic and electrical power systems due to its capability of ultrafast charging-discharging and ultrahigh power density. Nevertheless, its energy density is still limited by the low dielectric constant (≈ 2.2) of the commercial dielectric polypropylene (PP). The conventional enhancement strategy by embedding inorganic fillers in PP matrix is still difficult and challenging due to that PP hardly dissolves in any inorganic/organic solvent. In this work, we develop a new strategy including freeze-drying, surface functionalization, and hot-pressing to incorporate Ti_0.87O₂ monolayers in PP film. A series of uniform composited Ti_0.87O₂@PP film has been successfully fabricated with Ti_0.87O₂ content range of 0-15 wt%. The maximum dielectric constant of the as-prepared Ti_0.87O₂@PP film is 3.27 when the Ti_0.87O₂ content is 9 wt%, which is about 1.5 times higher than that of pure PP. Our study provides a feasible strategy to embed two-dimensional material into commercial PP thin-film with superior dielectric performance for practical application.