Dense Hydrogen Bond Network Design of High-Strength Glycidyl Ester to Enhance the Mechanical Properties of Its CFRPs

The significant disparity between the compressive and tensile strengths of carbon fiber reinforced polymer (CFRP) composites restricts their widespread application. Designing and developing epoxy resin matrix materials with high strength and modulus is crucial for improving the compressive performance of composites. Here, carbonyl groups are introduced into the molecules as hydrogen bond receptors, and a novel trifunctional glycidyl ester TAEP is successfully synthesized. The construction of a dense hydrogen bond network achieves remarkably high tensile strength. The reaction mechanism of TAEP with various aromatic amine curing agents is investigated for the first time using DFT calculations, revealing that the hydrogen proton transfer leads to the formation of hydroxyl groups, which can effectively prevent the oxygen anions from damaging the ester groups. And m-phenylenediamine (MPD) with lower nucleophilic reaction energy barriers and higher hydrogen proton transfer energies is the preferred choice as a curing agent for glycidyl esters. The cross-linking network structures are characterized through PALS, BDS, LF-NMR, XRD, molecular dynamics simulations, and in situ IR, indicating that the presence of ester groups facilitates the activity of local motion, while the inherent hydrogen bond receptors provide more interaction sites. The enhanced intermolecular interactions and superior force transmission capability of TAEP contribute to its tensile strength reaching 111.92 MPa, significantly surpassing commercial resins like TDE85 and mAFG90 systems. Additionally, the TAEP system exhibits the highest compressive strength in CFRPs (1247.91 MPa). This result offers substantial value and potential for the preparation and application of high-performance CFRPs.