Silicon-containing branched chains active esters as curing agents to improve dielectric properties of epoxy resin

C-Si bond was widely used to enhance the dielectric characteristics of polymers owing to its inherent low polarity. However, the potential of silicon-containing branched chains for modifying epoxy resins has been rarely explored. In this research, two active esters with silicon-containing branched chains of different chain lengths (DASIO, DASIOL), and another active ester with silicon-free branched chains (DAO) have been synthesized and utilized as curing agents of DCPD epoxy resins. After introducing silicon-containing branched chains, the loss factor (D f ) value of the cured epoxy system was significantly reduced. At 10 GHz, the D f values of DASIO/EP and DASIOL/EP systems were 6.47‰ and 6.82‰ respectively, reflecting decreases of 29.8% and 26% from the DAO/EP system value. With the extension of the chain length of silicon-containing branched chains, the cured epoxy system's dielectric constant (D k ) value exhibited a downward trend. When compared to the DASIO/EP system, the D k value of the DASIOL/EP system showed a reduction from 2.84 to 2.62. The silicon-containing branched chains could improve the flexibility of the cured epoxy system. The elongation at break of DASIOL/EP system was 4.2%, which have increased by 30%, in comparison to the DAO/EP system. In addition, through introduction of silicon-containing branched chains, the cured epoxy system also showed improved thermo-mechanical properties, hydrophobic properties and thermal stability. The research findings indicated that the silicon-containing branched chains were capable of enhancing the dielectric performances of the epoxy system. Additionally, by regulating the length of the silicon-containing branched chains, a balance of mechanical properties, thermal properties, etc. could be achieved. This provided a novel approach for developing low-D f epoxy materials in the electronics industry.