Femtosecond laser texturing assisted cold plasma hydrophilization of polytetrafluoroethylene surface

Polytetrafluoroethylene (PTFE) is one of the most widely used engineering polymers, but PTFE-based bonding pairs are prone to failure due to its natural hydrophobicity induced weak interfacial bonding strength. Herein, we propose to improve the hydrophilicity of PTFE surface by femtosecond laser texturing assisted cold plasma modification. Specifically, PTFE surface is firstly textured by femtosecond laser ablation, and then modified by either direct cold plasma treatment or cold plasma induced graft polymerization of acrylic acid. The synergetic treatment roughens the PTFE surface on both micro and nano scales and introduces a large amount of oxygen-containing groups, making the treated surface hydrophilic (water contact angle < 30°). The hierarchically rough and hydrophilic PTFE surface favors its bonding with Cu by forming a mechanically interlocked and robust adhesive interface, and the maximum shearing strength and peeling strength of the bonding pairs were measured to be 2.75 MPa and 6.37 N/mm, respectively. The laser texturing assisted plasma modification enables durable surface hydrophilization and adhesive property improvement for PTFE compared with other previously reported methods, and thereby offers new insights into the fabrication of high-performance PTFE-based bonding components, as well as other functional units that require high-efficiency surface hydrophilization and robust bonding.