Enhancement of Pressure-Sensitive Adhesive by CO2 Laser Treatment

Pressure-sensitive adhesives (PSAs) are polymeric films that can be adhered to and detached from surfaces without leaving residue. Researchers are looking to enhance the bond strength between PSAs and different substrates. It can be achieved by tuning PSA's peeling, shear, and tack properties for every specific case. ‘Very High Bond’ (VHB) is a widely used PSA because of its high compliance suitable for stretchable and soft-matter devices. In this study, a simple and fast surface treatment approach to modify the adhesion of VHB by CO2 laser engraving is reported. We characterized this surface treatment method for VHB with different substrates. Multiple laser settings were tested for each material combination to determine the conditions at which the surface adhesion would be the highest. Tests on mechanical properties, ablation directions, chemical composition, tackiness, surface viscosity, and peeling forces were conducted to understand the adhesion and viscoelasticity changes. A higher concentration of non-crosslinked materials was determined in the VHB structure after treatment than before. Thus, we reason that laser treatment changes the surface adhesion of the PSA by cleavage of the polymer network. This work provides a simple route for tuning peeling, shear, and tack forces of a popular VHB using common equipment.