Room temperature bonding of cycloolefin polymer by vacuum ultraviolet surface photoactivation

We have applied vacuum ultraviolet (VUV) irradiation to room temperature bonding (RTB) of cyclo-olefin polymer (COP). The COP surface was oxidized into oxygen functional groups through the VUV irradiation in air. The extent of oxygenation was evaluated by water contact angle (WCA), X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The obtained results showed that the concentration of oxygen functional groups increased with VUV-irradiation time. The VUV-irradiation conditions for RTB were optimized based on our finding that prolonged irradiation resulted in a decrease in bonding strength. Observation of the fractured surfaces indicated that cohesive failure occurred after the appropriate irradiation time, but deterioration of the surface layer occurred with longer irradiation times.