Introduction to BPDA Chemical Name: 3,3′,4,4′-Biphenyltetracarboxylic dianhydride Molecular Formula: C₁₆H₆O₆ Molecular Weight: 294.22 CAS Number: 2420-87-3 BPDA is an aromatic tetracarboxylic dianhydride compound , and one of the most important dianhydride monomers for synthesizing high-performance polyimides (PI) . Due to its rigid biphenyl structure and symmetric molecular backbone, BPDA significantly enhances the thermal stability, mechanical strength, and chemical resistance of polyimide materials. Consequently, it is widely used in aerospace, electronics, electrical insulation, and flexible display technologies . 1. Chemical Structure and Characteristics BPDA consists of two benzene rings linked by a carbon–carbon bond, with carboxylic anhydride groups attached at the 3,3′,4,4′ positions. This planar, highly conjugated, and rigid molecular architecture gives BPDA-based polyimides their exceptional properties: Excellent thermal stabil...
Rhodium(III) oxide ( Rh₂O₃ ， Rhodium oxide ， CAS: 12 036-35-0) is a gray, high-melting-point inorganic compound that is extremely insoluble in water. It possesses excellent thermal stability and chemical inertness, characteristics that determine its outstanding applicability under high temperatures and harsh environments. For example, rhodium hydroxide is insoluble in common solvents, with a melting point of about 1100 °C and a density of approximately 8.2 g/cm³. Due to its strong stability and basic oxide nature, rhodium oxide is often used as a component of high-temperature structural materials, optical ceramics, and high-performance electronic materials. In rhodium oxide thin films, reversible electrochromic properties (visible light changing between yellow ↔ green) as well as photoconductive behavior similar to ITO (indium tin oxide) transparent conductive oxides have been observed. These physicochemical properties lay the foundation for the application of rhodi...