Theoretical Studies Of The Hydrogen Bonding Latent Curing Agent For Epoxy Resin

Epoxy resins are widely employed as electric insulating materials, adhesives or protective coatings, when cured with suitable curing agents. One-component epoxy system mixed with the epoxy resin and latent curing agents does have the advantages of easier operation, less environmental pollution and higher product quality, and it has become one of the hot research topics in the field of epoxy curing agents in recent years.In previous experiments, our research group has mixed novolac resin with DMP-30 using the melting or solvent method to prepare a new kind of latent curing agent for epoxy resin. In this paper, the dispersion correction using density functional theory (B3LYP-D3) quantum chemistry calculation method, the geometric parameters,interaction energies, frequency analysis, NBO analysis, electron density topological analysis, thermodynamic analysis, solvent effect and so on, to study the interaction of hydrogen bonds in the complexes.1. The study of the hydrogen bonding between the oligomer model (n=2) of the novolac resin and DMP-30 was carried out, and then its latent curing mechanism was preliminary interpreted,2. A series of analysis and calculation were carried out to investigate the influence of the structure and stability of the novolac resin (n=3?8),and the cauculated results were compared with the experimental results.The results shows that, with the increase of the chain length of novolac resin, the hydrogen bonded complexes are more and more stable. In practical application, it is more appropriate to select novolac resin (n=6?8). With the increase of temperature,the spontaneous tendency of hydrogen bond rupture process becomes larger, the stability of the complexes decreases, and the intermolecular hydrogen bondassociation gradually weakens. Therefore, the complexes shows good latency at room temperature, and the curing reaction can be carried out when the temperature is raised.3. The solvent effects of methanol, ethanol and acetone on novolac resin,DMP-30 and their complexes were investigated by explicit and implicit solvation model.The results shows that, the complexes are more stable and have better latent when using higher-polar solvent, such as methanol.4. The study of the hydrogen bonding between the novolac resin and DETA was carried out.The results shows that,novolac resin and DETA could also form a complex structure with strong hydrogen bonding effect. Compared with DMP-30, DETA has a smaller molecular volume and the amino groups are more concentrated. When the chain length of novolac resin increases, it is easier to form the inclusion structure and the stability of the complex is stronger. On the basis of the above theoretical results, it is expected to prepare a new type of potential curing agent for epoxy resin.