Pressure-sensitive adhesives (PSAs) are extensively used in diverse applications such as semiconductor manufacturing, labeling, and healthcare because of their quick and viscoelasticity-driven physical adhesion to dry surfaces. However, most of the existing PSAs normally fail to maintain or even establish adhesion under harsh conditions, particularly underwater, due to the lack of robust chemical functionalities for chemistry-based adhesion. Meanwhile, these PSAs are incapable of altering the adhesion in response to external stimuli, limiting their employment in applications requiring dynamic adhesion. Here, we develop a chemically functionalized PSA (f-PSA) with enhanced and phototunable underwater adhesion by incorporating an underwater adhesion enhancer (i.e., mussel-inspired catechol) and a photoresponsive functionality (i.e., anthracene) into a standard acrylic PSA matrix. The synergistic coupling of viscoelasticity-driven physical adhesion originating from the matrix with catechol-enabled chemical adhesion secures sufficient interfacial molecular interactions and leads to enhanced underwater adhesion. The efficient dimerization of anthracene via light-triggered cycloaddition facilely mediates the viscoelastic property of f-PSA, rendering the phototunable adhesion. We envision that this f-PSA can open up more opportunities for applications such as underwater manipulation, transfer printing, and medical adhesives.
Keywords: anthracene; catechol; pressure-sensitive adhesives; tunable adhesion; underwater adhesion.