Femtosecond-Laser-Induced Blister Formation on Polymer Thin Films

Surface adhesion of back-illuminated ultrafast laser-treated polymers

“…Despite the losses in the substrate, the remaining energy delivered to the polymer film at the interface leads to a blister formation. Increasing the energy, especially for a low NA lens, will lead to continuum generation and breakdown in the substrate, but still the blister expands [13]. In this section, we report pulse energies delivered through the substrate accounting for the nonlinear absorption in the substrate.…”

“…This observation confirms what we expect. When an ultrafast laser pulse is focused on the material interface, it forms a plasma [12][13]. At the temperature that we achieve, the material vaporizes and undergoes a chemical change creating the embedded layer and the solidified material on glass, as seen in Fig.…”

“…The increase in contact angle by 13° is due to the increased surface roughness caused by formation of blisters. Since the film thickness was 1.3 µm, we lowered the energy to avoid rupturing of the film [13]. We decreased the energy to 260 nJ for N = 2 and 220 nJ for N = 4.…”

“…In contaminant-free LIFT, the nonlinear interaction of an ultrafast pulse with the polymer film (often called a dynamic release layer (DRL)) between a glass substrate and transfer material, ensures confinement of chemical changes to the glass-polymer interface, leaving the transfer material unaffected [12]. When an ultrafast pulse (duration of ~ a few femtoseconds) interacts with a polymer film at the interface, it creates a localized hot plasma [13][14]. The hot plasma expands leading to formation of a blister.…”