Surface functionalization of poly(ether ether ketone) by wet-chemical modification with carboxylic acids and diamine

Polyaryletherketones (PAEK) are high-performance plastics with excellent mechanical properties and high thermal resistance used, e.g. as material for implants. Their molecular structure gives them a high level of chemical inertness but prevents bonding and adhesive interactions with other materials and integration into body tissue. Using the example of poly(ether ether ketone) (PEEK), we show novel synthetic routes for wet-chemical modification of the surface to create reactive carboxylic and amino groups. In a first approach, the ketone functionalities of the PEEK molecules were reduced to hydroxy groups and subsequently esterified with carboxylic acids. Using dicarboxylic acids, one acid group was bonded covalently to the PEEK surface while the other provided free acidic functionalities. In a second approach, the PEEK surface was modified in one step by reaction of the ketone group with a diamine, creating primary amino groups on the PEEK surface. All reaction products were analyzed by a powerful combination of surface sensitive X-ray photoelectron spectroscopy (XPS) and advanced infrared spectroscopic methods.