Mechanics of Peeling Adhesives From Soft Substrates: A Review

Understanding peeling behavior in soft materials is integral to diverse applications, from tissue engineering, wound care, and drug delivery to electronics, automotive, and aerospace equipment. These applications often require either strong, permanent adhesion or moderate, temporary adhesion for ease of removal or transfer. Soft adhesives, especially when applied on soft substrates like elastomer-coated release liners, flexible packaging films, or human skin, present unique mechanical behaviors compared to adhesives applied on rigid substrates. This difference highlights the need to understand the influence of substrate rigidity on peeling mechanics. This review delves into both energy- and stress-based analyses, where a thin tape with an adhesive layer is modeled as a flexible beam. The energy analysis encompasses components like the energy associated with tape deformation, kinetic energy, and energy lost due to interfacial slippage. The stress analysis, on the other hand, focuses on structures with thin, deformable substrates. Substrates are categorized into two types: those undergoing smaller deformations, typical of thin soft release liners, and thicker deformable substrates experiencing significant deformations. For substrates with small deformations, the linear Euler–Bernoulli beam theory is applied to the tape in the bonded region. Conversely, for substrates experiencing significant deformations, large deflection theory is utilized. These theoretical approaches are then linked to several practical, industrially relevant applications. The discussion provides a strategic guide to selecting the appropriate peeling theory for a system, emphasizing its utility in comprehending peeling mechanisms and informing system design. The review concludes with prospective research avenues in this domain.