Reactive Janus‐ <scp> SiO ₂ </scp> Reinforced Acrylic‐Polyisobutylene Semi‐Interpenetrating Pressure‐Sensitive Adhesive: The Combined Effect of Crosslinking and Entanglement

ABSTRACT Uncrosslinked pressure‐sensitive adhesives (PSAs) typically suffer from low cohesive strength and high cold flow, which significantly limit their practical applications. This study proposed a strategy to improve the performance of uncrosslinked pressure‐sensitive adhesives by using a Janus‐nanoparticle‐toughened three‐dimensional network structure. Specifically, reactive Janus nanoparticles (JPs) were designed and reinforced polyisobutylene/acrylic polymer semi‐interpenetrating network (Semi‐IPN) PSAs via a combination of free radical‐initiated cross‐linking and chain entanglement. The morphological structure, mechanical performance, adhesion properties, and rheological behavior of the Semi‐IPN PSAs were systematically investigated. The results demonstrated that the shear strength and peel strength of PSAs that retained the unique properties of polyisobutylene (PIB) increased by 362% and 301%, respectively. In addition, although the initial tack dropped by two grades, the cold flow was significantly reduced. This multiple interaction between the reactive JPs and the PSAs matrix substantially improves the performance of uncrosslinked PSAs. This offers valuable insights for the rational design of high‐performance adhesive systems.