One-pot solvent-free synthesis of self-catalyzed phosphorus/silicon cycloaliphatic epoxy resin with excellent flame-retardant and dielectric property

Developing superior flame-retardant and low dielectric epoxy resins used in electronics remains a great challenge. Herein, two cycloaliphatic epoxy molecules (CFP, CFDP) were designed by incorporating phosphaphenanthrene (DOPO) into a cyclic silicon resin (CFS) through one-pot solvent-free process. CFP and CFDP exhibited self-catalyzed ability toward anhydride hardener (MHHPA). Both CFP/MHHPA and CFDP/MHHPA resins achieved UL-94 V-0 rating with limited oxygen index of 26.5 % and 36.5 % owning to the emission of silicon/ phosphorus-containing segments in gas phase and enhancement of carbonation ability. Moreover, incorporating DOPO well-maintained the thermal stability and enhanced char yield in air, thus significantly suppressing heat release during combustion. Meanwhile, CFP and CFDP imparted epoxy resins with excellent dielectric properties. The dielectric loss of CFP/MHHPA and CFDP/MHHPA was 0.005 and 0.006 at 10 MHz, and dielectric constant was remained at 3.36. This work offers a facile and practical way to fabricate multifunctional epoxy resins used in electronic field.