Min Zhao,Fahu Yang,Dinggao Wang,Chao Zhang,Shaomin Zhou,Lin Li,Zhongming Li,Haili Zhao,Tao Chen
The development of porous films with biodegradability, high electromagnetic interference (EMI) shielding, and thermal conducting performance for advanced electronics is urgent. Herein, a superthin and flexible film composed of PBAT/MWCNT and PEDOT:PSS/PEO/SWCNT is fabricated through combining electrospinning and spin-coating. In this work, the content of PEO and SWCNT should be controlled to 1 and 10 wt % for achieving the optimal layered-cavity structure within the film, guaranteeing the proper flow ability of the suspension. The robustly constructed layered-cavity structure within the film allows the electromagnetic waves to suffer multiple reflections, which enhances the EMI shielding performance. Meanwhile, the structure also plays an important role in promoting the electric and heat conduction of the film. Consequently, the film with a thickness of 0.14 mm exhibits the most optimal EMI shielding efficiency (SE) of 26.02 dB, electrical conductivity of 40.371 S/m, and thermal diffusion coefficient of 0.124 mm2/s. The EMI SE/thickness is about 185.86 dB/mm, attaining a cutting-edge level compared to reported polymer-based films. Besides, the PEO or SWCNT content should be controlled, and the two-side spin-coating is also needed for thicker films. This work offers a method to develop superthin biodegradable films with excellent performance, positioning it as a strong alternative for flexible electronics.
A high dielectric constant and electric breakdown strength are desired in high-energy-density polymer/ceramic composites. Ultrahigh interface leakage conduction between polymer and carbon nanotubes (CNTs) hinders the development of CNT-filled composite dielectrics. In this work, composite dielectrics bearing V2C MXene-CNT hybrid-particles were fabricated. Environment-friendly polyvinyl alcohol (PVA) was employed as the matrix. Interface polarization between PVA and ceramics improved the dielectric constant of composites. A switchboard micro-structure was obtained in the hybrid-ceramic consisting of layered V2C and thread-like single-walled carbon nanotubes (SWCNTs). This micro-structure led to adsorption-migration of fluorine from V2C to CNTs, triggering Coulomb-blockade zones at CNT surfaces supported by first-principles molecular-dynamics calculations. Interface leakage conduction between CNTs and PVA was depressed by quick-slow-quick (QSQ) electron transmission of CNTs. Compared to PVA/CNT composites, PVA/V2C–CNT composites exhibited a favorable high dielectric constant, strongly depressed low dielectric loss and conductivity, and elevated high breakdown strength. The ternary composite with 5 wt% hybrid-ceramic showed a dielectric constant of ∼232 (122 times that of PVA) and a dielectric loss of ∼0.2 (1.4 times that of PVA) at 100 Hz, as well as a breakdown strength of ∼35 MV m−1 (60% of that of PVA). A balance of high dielectric constant and breakdown strength was achieved in the ternary system. This work might enable large-scale preparation of high-performance composite dielectrics.
危险品化学品经营许可证（带存储）