“Computational Insights into Underwater Self-Healing Dynamics of Urethane, Urea, and Disulfide Bonds’’
Maryam Bonyani
Self-healing polymers are essential for enhancing the durability and sustainability of materials in harsh environments. Dynamic covalent bonds, such as urethane, urea, and disulfide linkages, offer chemical reversibility and recyclability, making them promising candidates for underwater self-healing systems. However, the reaction mechanisms and energetics of these bonds in aqueous conditions remain poorly understood. This study employed Density Functional Theory (DFT) using Gaussian 16 at the B3LYP/6-31+G(d,p) and ωB97X-D/def2-TZVP levels with the SMD implicit solvation model to investigate their thermodynamic and kinetic behavior. Geometry optimization, transition state identification, intrinsic reaction coordinate (IRC) analysis, and bond dissociation energy (BDE) calculations were conducted in both vacuum and water. Results showed that urethane bonds exhibit a high activation barrier (∆G‡ = 30.2 kcal/mol) and strong bond stability (BDE = 207.2 kcal/mol), while urea bonds follow a dual-transition-state mechanism, with the second transition state as the rate-determining step (∆G‡ = 22.3 kcal/mol; BDE = 181.8 kcal/mol). Disulfide exchange followed a three-step radical pathway, with S–S cleavage as the rate-limiting step (∆G‡ = 23.4 kcal/mol; BDE = 79.0 kcal/mol) and exhibited spontaneous reversibility in water (∆G = –6.42 kcal/mol). The high reverse activation energies of urethane and urea bonds may limit their self-healing capability at room temperature, whereas disulfide bonds could offer favorable reversibility and dynamic behavior in water, potentially making them suitable for underwater self-healing applications. The results of these simulations will be discussed along with an experimental kinetics study.
Wednesday, 04/16/2025 at 2:30 pm
CAMP 194
https://clarkson.zoom.us/j/95529580049
Biography:
Maryam Bonyani joined Clarkson University as a PhD student in Chemical Engineering in Spring 2023, under the supervision of Professor Sitaraman Krishnan. She holds a bachelor’s degree in chemical engineering from the University of Tehran and a master’s degree in chemical engineering from Sahand University of Technology (Tabriz), Iran. Her research focuses on developing self-healing polymers and biodegradable composites reinforced with natural fibers. She is also actively involved in computational studies using Density Functional Theory (DFT) to investigate the molecular mechanisms underlying dynamic covalent bonding in self-healing systems.