Hydrolytic degradation and property aging in highly crosslinked cyanate ester resins: A computational study

• QC calculation identifies hydrolysis mechanisms with different water molecules • Highlights the critical role of hydrogen-bond networks in accelerating degradation • Incorporated QC pathways into MD to build different hydrolysis rates polymer models. • Linked microstructural changes during hydrolysis to aging of material properties The hydrolytic degradation of thermosetting resins significantly reduces their glass transition temperature (Tg), limiting their performance under humid conditions. In this work, we present a multiscale simulation framework to elucidate the hydrolytic degradation mechanism of cyanate ester (CE) resins under neutral environments by integrating high-accuracy quantum chemistry calculations with traditional molecular dynamics (MD) simulations, using a hydrolysis–global reaction route mapping (GRRM)/Monte Carlo (MC)/MD approach. A 2-H 2 O hydrolysis mechanism including reaction pathway and reaction energy in CE resins was identified via the GRRM method and implemented into MD simulations to construct realistic hydrolyzed models and predict degradation-induced property changes. Analysis of physicochemical properties confirms that the simulated structures closely resemble those observed experimentally. Microstructural analysis further reveals that increasing hydrolysis leads to enhanced chain mobility and reduced chain stiffness, thereby accelerating the aging of the material's physical properties. These results provide a molecular-level understanding of hydrolytic degradation in CE resins and offer a comprehensive view of humidity-induced polymer aging. This integrated approach supports the rational design of more durable polymeric materials.