Self-Healing Mechanism of Supramolecular Gel Particles under High-Temperature and High-Salinity Conditions: A Molecular Simulation Study

Abstract

In heterogeneous reservoir development, profile-control agents repeatedly experience the cycles of temporary bridging, fracture-enabled unblocking, and replugging caused by accumulation. Hence, the self-healing capability acts as an effective route to improve the plugging efficiency. Currently, most self-healing materials are evaluated under mild conditions. Their applicability and mechanisms at high-temperature/salinity reservoirs remain unclear. Herein, a supramolecular block copolymer, PS-b-P(AAc-alt-DMAAm), is investigated by molecular dynamics simulations to clarify how high temperature and salinity regulate the self-healing behavior of gel particles. The results suggest that moderate heating can increase chain mobility and promote interfacial interdiffusion, thereby accelerating contact formation and supporting polymer interpenetration across the interface. By contrast, further elevating temperature weakens noncovalent interactions and destabilizes the interface. As a result, the highest self-healing efficiency is achieved at an intermediate temperature of around 343 K, where a balance between molecular mobility and interfacial stability is maintained. With respect to salinity, moderate ion concentrations can reduce interchain electrostatic repulsion through Na+ screening and transient ionic cross-linking, thereby enhancing the interfacial adhesion. However, excessive salinity leads to the formation of rigid static crosslink networks that suppress self-healing. The optimal self-healing performance is obtained at a salinity of 100 g/L, which provides a balance between the dynamic interactions and restricted chain mobility. These findings reveal a general mechanism in which the interplay between molecular mobility and reversible noncovalent interactions governs interfacial self-healing in supramolecular gels, providing molecular-level insights into tuning interfacial properties in complex environments.