Surface Modification of Poly(ether ether ketone) through Friedel–Crafts Reaction for High Adhesion Strength

Abstract

Poly­(ether ether ketone) (PEEK) possesses attractive mechanical and thermal properties but demonstrates poor adhesion. To overcome this disadvantage, in this study, the surface modification of PEEK or PEEK-based carbon-fiber-reinforced thermoplastics (CFRTP) was performed through the Friedel–Crafts reaction and successive epoxidation. Under optimized reaction conditions, surface modification was achieved without surface deterioration, and epoxy groups were introduced. The progress of the Friedel–Crafts reaction and epoxidation was demonstrated by X-ray photoelectron spectroscopy measurements after fluorine labeling through thiol–en reaction and amine addition, respectively. The adhesive strength between CFRTP and epoxy adhesives was increased to 23.5 MPa, and cohesive fracture of epoxy adhesives, rather than interfacial peeling, occurred. In addition, compared with conventional plasma treatment, the durability of the modified surface and thickness of the modified surface layer increased. Therefore, we succeeded in modifying the surface properties through the epoxidation of the PEEK surface.

Design strategies for composite matrix and multifunctional polymeric scaffolds with enhanced bioactivity for bone tissue engineering

“…Chemical modification methods include wet chemical reaction ( Duan and Wang, 2006 ), click chemistry ( Bayraktar et al, 2012 ), crosslinkers assisted modification ( Yang and Moloney, 2017 ). Further, the crosslinking-assisted modification encompasses of various crosslinkers like carbodiimide ( Ikeda et al, 2010 ), aldehyde ( Lin et al, 2016 ), ether ( Miyagaki et al, 2019 ) and green crosslinking agents ( Hubbe et al, 2015 ). In order to overcome the main drawbacks associated with chemical methods, which frequently require stringent process control, may result in environmental issues due to the chemical agents used, and may involve undesirable changes in the polymer surface morphology, surface treatment methods based on physical principles have been developed to introduce oxygen-containing functional groups on to polymer surfaces.…”

Adhesion Promoting Copolymer of Acetate-Protected Vinyl Catechol with Glycidyl Methacrylate: Unraveling Deprotection, Adsorption, and Adhesion Behaviors on Metal Substrates

“…Several surface treatment methods have been reported to strengthen the interfacial interactions between epoxy adhesives and adherends. − For example, cleaning surfaces through plasma/UV irradiation can form hydroxyl groups and effectively increase the wettability of adhesives on the adherend surfaces. , Nevertheless, the improved interactions remain to be the secondary bonding interactions such as van der Waals bonds or hydrogen bonds, which are inherently weak (10–50 kJ/mol), and the improved wettability is usually not maintained for a long period when stored under the ambient conditions . In contrast, coating a thin primer layer on the adherend surface containing reactive functional groups such as amine or epoxide units is a feasible and commonly used approach to form stronger primary bonding (300–500 kJ/mol) for epoxy/amine-based adhesive systems. , …”

Improve the Interfacial Properties between Poly(arylene sulfide sulfone) and Carbon Fiber by Double Polymeric Grafted Layers Designed on a Carbon Fiber Surface

“…However, the interfacial interaction between CF and thermoplastic resin is indeed weak, which can be attributed to the lack of active groups in the thermoplastic chains as well as the extremely inert graphite structures on a carbon fiber surface, − making it very difficult to create effective physical and chemical bonding as well as outstanding interfacial properties. Similarly, the lack of reactive groups of molecular chains for a thermoplastic matrix always results in a big obstacle in the formation of chemical bonds with carbon fiber. , Consequently, in order to increase the interfacial interaction, improve the thermal and mechanical performance, and broaden the application field for the thermoplastic composite, some methods and equipment for modifying the interphase of composite have emerged as the times require, such as oxidation, γ-ray irradiation, electrochemical or grafting modification, , and some other nanoparticle modification. − Nevertheless, there are several concerns in the above method, which was applied in the enhancement to the interface of CF/PASS composite, such as, carbon fiber will be corroded under strong acid conditions, destroying the original structure and causing the performance of carbon fiber itself to decline . Therefore, in our research, a double polymeric grafted layer was constructed on carbon fiber with polydopamine (PDA) film and NH 2 –PASS molecular chains, respectively, which can act as a solid bridge to build a reliable interphase between carbon fiber and matrix by chemical and physical bonds.…”