Decoupling of Cohesive Fracture and Interfacial Detachment in Pressure‐Sensitive Adhesives Based on Amphiphilic Triblock Copolymers

ABSTRACT This work systematically investigates the adhesion behavior of pressure‐sensitive adhesives (PSAs) by synthesizing an amphiphilic triblock copolymer, poly(benzyl acrylate)‐block‐poly(2‐hydroxyethyl acrylate)‐block‐poly(benzyl acrylate) (PBzA‐ b ‐PHEA‐ b ‐PBzA), featuring tunable terminal block lengths. The PSA design harnesses synergistic interactions between dynamic hydrogen bonding in the mid‐block and physical crosslinking at the end‐blocks. A four‐region stress–strain phase diagram was constructed based on distinct debonding modes, while curves correlating adhesive energy to debonding velocity were derived using the time–temperature superposition principle, which enabled the decoupling of bulk viscoelastic dissipation from interfacial adhesive energy contributions. The results revealed that increasing terminal block lengths enhances mechanical performance but reduces adhesive energy at fixed debonding velocities. A modified Lake‐Thomas model confirms consistent interfacial adhesive energy across the three systems. This study demonstrates how tuning structural parameters in block copolymer architectures governs adhesion properties, providing new insights for developing robust yet flexible PSA systems through molecular architecture optimization.