Ultra-high modulus epoxy resin reinforced by intensive hydrogen bond network: From design, synthesis, mechanism to applications

According to classic polymer physics, free volume is the decisive factor for the modulus of resin matrix. In rigid epoxy resin systems with high crosslink density, it's difficult to further reduce the free volume. Designing new epoxy resins from the perspective of molecular structure design is a feasible approach, however, how to select potential structures is a great challenge. In this paper, a polar epoxy resin with amide bond was efficiently synthesized, which was ingeniously designed according to the relationship between structure and performance as well as high-throughput screening. The free volume of this resin could be reduced by introducing high density of hydrogen bonds with strong bond energy based on Density Functional Theory (DFT) calculations. After formulation design, the flexural modulus of this resin was up to 6568 MPa using m-phenylenediamine (MPD) as curing agent, which is the highest level ever reported, and the theoretical mechanism of hydrogen bond on the modulus enhancement for high crosslink density epoxy resin was investigated in detail. The resin with ultra-high modulus as well as good interface property has great potential in high-performance carbon fiber composite industry.