Preparation of Polyimide Films with Ultra-Low Dielectric Constant by Phase Inversion

Due to the high value of its dielectric constant, polyimide does not meet the requirements of the development of integrated circuits and high-frequency printed circuits. The development of novel low dielectric constant polyimide materials for the preparation of flexible copper clad laminates is of theoretical and practical significance in the application of polyimide for 5G communications. In this work, different fluorinated graphene/polyamic acids (FG/PAA) were used as the precursor, and the porous polyimide film was successfully prepared by phase inversion. The dielectric constant of the porous polyimide film is relatively low, being less than 1.7. When the content of fluorinated graphene is 0.5 wt%, the overall dielectric performance of the porous film is the best, with a dielectric constant of 1.56 (10 kHz) and a characteristic breakdown field strength of 56.39 kV/mm. In addition, the mechanical properties of the film are relatively poor, with tensile strengths of 13.87 MPa (0.2 wt%), 13.61 MPa (0.5 wt%), and 6.25 MPa (1.0 wt%), respectively. Therefore, further improving the breakdown resistance and mechanical properties of the porous film is essential for the application of porous ultra-low dielectric polyimide materials.

Efficient Adsorptive of Carbofuran Via Tailored Porous Polyacrylonitrile Film Incorporated Ti-MIL Coordination Polymer

Carbofuran is largely applied insecticide which resulted in its wide spreading in ground/surface water and food products and consequently investigation of efficient techniques for removal of carbofuran is extensively considered. Herein, facile approach for removal of carbofuran was developed via exploitation of highly adsorptive porous film based on polyacrylonitrile (PAN) and NH2-MIL-Ti as a coordination polymer. NH2-MIL-Ti@P-PAN film was prepared by immobilization of NH2-MIL-Ti within the pre-prepared porous (P-PAN) film. The pore diameter of PAN film was estimated to be 8.5 – 51.2 µm. The removal of carbofuran from the porous film was systematically studied and fitted to both pseudo 2nd ordered and Langmuir models. Results showed that Langmuir maximum removal of carbofuran was largely enhanced from 292.2 mg/g for P-PAN to 489.5 – 690.1 mg/g for NH2-MIL-Ti@P-PAN. Thus, by increasing the amount of immobilized NH2-MIL-Ti@P-PAN in the film, the adsorption capacity of carbofuran was markedly improved, reaching a 2.4 times higher when 30% NH2-MIL-Ti is immobilized. Importantly, after six reusing times, the removal of carbofuran by 30% NH2-MIL-Ti@P-PAN film was decreased by only 12.5%. The overall results attest that the fabricated NH2-MIL-Ti@P-PAN film could be efficiently used for trace removal of various insecticides and other environmental applications.

One-Step Dynamic Fabrication of Asymmetric Multi-Layered Porous Films for Sustained Drug Delivery

Asymmetric multi-layered porous film was prepared by casting inverse emulsion following the breath figure method. The porous morphologies both on the surface and in the bulk of the fabricated film...