Session: Research Posters

Paper Number: 173822

Molecular Dynamics Study of Self-Healing and Thermomechanical Response in Epoxy-Amine Vitrimer Networks 

Vitrimers represent a major advancement in polymer science, combining the mechanical strength of thermosets with the recyclability and reprocessability of thermoplastics. Unlike conventional thermosets, which form permanent covalent networks after curing, vitrimers incorporate dynamic covalent bonds that enable bond exchange reactions (BERs). These reversible linkages allow the network to rearrange in response to external stimuli while retaining crosslink density, enabling properties such as stress relaxation, self-healing, creep resistance, and thermal remolding. As a result, vitrimers offer a sustainable alternative to traditional polymers, with growing applications in aerospace, automotive, adhesives, coatings, and high-performance composites where both durability and reprocessability are desired.

This research focuses on epoxy-amine based vitrimer networks, modeled at the molecular level using atomistic molecular dynamics (MD) simulations. The vitrimer formulation studied in this work includes diglycidyl ether of bisphenol A (DGEBA) as the diepoxide and 4-aminophenyl disulfide (AFD) as the aromatic diamine hardener, selected to represent reprocessable epoxy-based networks with dynamic S–S bond exchange. The curing process is designed to replicate primary and secondary amine crosslinking, forming a permanent yet reconfigurable network. Bond exchange behavior is introduced post-curing to capture vitrimer-specific responses to temperature and mechanical load. The simulation workflow includes initial monomer optimization, amorphous cell packing, thermal and pressure equilibration, bond network formation, and deformation under tensile and triaxial strain conditions. Temperature-controlled simulations are conducted to probe the influence of BER activity on molecular rearrangement, stress dissipation, and plasticity.

Self-healing is investigated by introducing controlled damage into the network and allowing it to recover under thermal activation. Stress-strain curves of healed networks are compared to their pristine counterparts to quantify recovery in terms of interfacial bonding, molecular interpenetration, and mechanical performance. The relationship between BER rate and healing efficiency is explored by varying temperature and observing the kinetics of bond reforming and mechanical restoration.

A key aim of the study is to map the trade-off between mechanical integrity and dynamic adaptability across thermal conditions. While elevated temperatures accelerate BERs and enhance healing, they can also lead to over-relaxation and weakened structural response. Conversely, lower temperatures preserve mechanical strength but reduce reprocessability. By capturing this balance, we aim to define optimal processing windows that preserve durability while enabling vitrimer function.

The results of this work will provide fundamental insights into vitrimer behavior under varying thermal conditions, helping to optimize vitrimer formulations for real-world applications. Understanding how temperature influences stress relaxation, plasticity, and self-healing efficiency is crucial for tailoring vitrimer properties to specific engineering needs. These findings will contribute to the design of next-generation recyclable, self-healing thermosetting materials, advancing sustainable material technologies and expanding the practical applications of vitrimers in high-performance, reprocessable polymer systems.

Presenting Author: Praneel Singla San Diego State University

Presenting Author Biography: Praneel is currently a graduate student in the integrated 4+1 B.S./M.S. program at San Diego State University, pursuing a Bachelor of Science in Mechanical Engineering and a Master of Science in Bioengineering. His research, under the guidance of Dr. Sara Adibi, focuses on vitrimers, where he utilizes atomistic modeling to explore their mechanical behavior, self-healing properties, and potential applications in biomedical engineering. Through his work, he aims to contribute to the advancement of sustainable and reprocessable biomaterials for future engineering applications.

Authors:

Praneel Singla San Diego State University
Sara Adibi San Diego State University