Effective fabrication of flexible nickel chains/acrylate composite pressure-sensitive adhesives with layered structure for tunable electromagnetic interference shielding

Functional adhesives with electromagnetic interference (EMI) shielding capabilities are urgently required to protect portable electronic products and wearable devices from unwanted microwave radiation. However, it is still a huge challenge to achieve the combination of strong adhesion, electrical conductivity, and superior EMI shielding characteristics for the adhesives. Herein, an EMI shielding functional and flexible adhesive is fabricated by incorporating nickel (Ni) chains into acrylate pressure-sensitive adhesive (a-PSA) via the solution casting technology. Correlations between the structure, adhesive properties, electrical behaviors, and electromagnetic characteristics are extensively investigated. The strong adhesive property and effective EMI shielding capability are achieved simultaneously via the unique spatial distribution of Ni chains. The adhesive failure mode changes from mixed failure to interfacial failure with the Ni chain content. The dielectric and electromagnetic properties are revealed with respect to electrical conductivity, complex permittivity, permeability, and relaxation behaviors. The electromagnetic characteristics are mainly controlled by the spatial distribution of Ni chains, which can be facilely modulated by the particle concentration. At the optimum content of Ni chains (30.0 wt.%), the composite adhesive exhibits a strong EMI shielding effectiveness (SE) of up to 39.97 dB with a thickness of 0.18 mm. At the same time, a sufficient peel strength of 39.56 N/m, shear strength of 41.07 kPa, and the static shear adhesion of 612.87 min under 16.33 kPa shear strength are achieved. An absorption-dominated shielding mechanism is demonstrated. Additionally, the composite adhesives can be easily attached onto various material surfaces by just light finger touch. The findings of this study improve the basic principles of adhesion with functional electromagnetic characteristics and provide a solid framework for the rational design of high-performance EMI shielding adhesives. Graphical abstract Flexible Ni chains/acrylate pressure-sensitive composite adhesives with excellent EMI shielding capabilities are elaborated via a scalable and versatile strategy.