Synthesis and Characterisation of Borate Ester for Brake Fluid Applications

Abstract Brake fluids are indispensable for ensuring the safety and reliability of automotive braking systems. Despite the increasing adoption of electric vehicles and regenerative braking technologies, conventional hydraulic brake fluids remain critical due to their ability to deliver rapid response times and minimal stopping distances. Among commercial formulations, glycol and borate ester based fluids such as DOT4 are widely used; however, there is limited open-research on the systematic synthesis and detailed characterization of their constituent compounds. In this study, a borate ester was synthesized through the esterification of boric acid with triethylene glycol monomethyl ether (TEGMME) and subsequently char acterized using a suite of physicochemical and spectroscopic techniques. Key perfor mance parameters,including equilibrium reflux boiling point (ERBP), wet ERBP, pH, density, and viscosity,were measured to evaluate the ester’s suitability for brake fluid applications. FTIR and GC-MS analyses confirmed the intended molecular structure and highlighted the presence of higher molecular weight species compared to commercial DOT4 fluids, suggesting potential improvements in thermal stability and performance. The results demonstrate that the synthesized borate ester exhibits excellent thermal stability, favorable rheological properties, and compatibility with established brake fluid specifications. These findings provide valuable insights into the design of advanced brake fluid formulations and establish a foundation for future studies on long-term durability, corrosion resistance, and formulation optimization.