RESUMO
Polyimides (PIs) are widely utilized polymeric materials for high-temperature plastics, adhesives, dielectrics, nonlinear optical materials, flexible hard-coating films, and substrates for flexible electronics. PIs can be facilely mass-produced through factory methods, so the industrial application value is limitless. Herein, we synthesized a typical poly(amic acid) (PAA) precursor-based solution through an industrialized reactor for mass production and applied the prepared solution to form thin films of PI using thermal imidization. The deposited PI thin films were successfully applied as gate dielectrics for organic field-effect transistors (OFETs). The PI layers showed suitable characteristics for dielectrics, such as a smooth surface, low leakage current density, uniform dielectric constant (k) values regardless of frequency, and compatibility with organic semiconductors. Utilizing this PI layer, we were able to fabricate electrically stable operated OFETs, which exhibited a threshold voltage shift lower than 1 V under bias-stress conditions and a field-effect mobility of 4.29 cm2 V-1 s-1. Moreover, integrated logic gates were manufactured using these well-operated OFETs and displayed suitable operation behavior.
RESUMO
The spherulitic and lamellar morphologies of melt crystallized isotactic polypropylene (iPP) have been investigated according to various crystallization temperatures and times. In this study, an appropriate chemical etching condition for the observation of iPP morphology by scanning electron microscopy (SEM) is determined. The optimum etchant formulation is 3 wt% potassium permanganate with the mixed solvent of sulfuric acid and phosphoric acid. The morphologies after etching reveal the microstructure of iPP clearly, such as the characterization of alpha/beta spherulites and the different lamellar growth patterns.
