P(VDF-TrFE-CTFE)/PMMA Films with Enhanced Dielectric and Breakdown Properties for EWOD

A dielectric film with high breakdown strength and dielectric constant are crucial for the reliable operation of electrowetting on dielectric (EWOD). In this study, barium titanate (BaTiO₃) nanoparticles modified with a silane coupling agent (KH550) were incorporated into poly(vinyl fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) and poly(methyl methacrylate) (PMMA) to prepare a BaTiO₃–KH550/P(VDF-TrFE-CTFE)/PMMA composite film to enhance the breakdown strength and dielectric constant of a dielectric layer. Results revealed that BaTiO₃–KH550 is uniformly dispersed within the P(VDF-TrFE-CTFE)/PMMA polymer matrix. When the BaTiO₃–KH550 content is 10 wt %, the dielectric constant reached 24.6, and the energy density was 2.65 J cm^–3, representing increases of 94% and 73%, respectively, compared to the pure P(VDF-TrFE-CTFE)/PMMA film, where was 12.7 and 1.53 J cm^–3. Additionally, the breakdown strength of all films remains above 150 kV mm^–1 due to the strong interfacial interaction between PMMA and P(VDF-TrFE-CTFE). Furthermore, the breakdown strength can keep at 194.90 kV mm^–1. Electrowetting experiments demonstrated that the composite film exhibited a high initial contact angle of 105.04°, with a contact angle variation range of 35.3° under a low DC voltage ranged from 0 to 50 V. The results indicated that this film is potential for applications in low-cost and high-dielectric-performance EWOD dielectric layer materials.