Polyetheretherketone Research Articles

Mathematical Modeling of Load Capacity and Durability of Metal-Polymeric Bearings with a Composite Bushing Based on Polyamides, Polytetrafluoroethylenes, Polyetheretherketones, or Polyethylene Terephthalates

Predictive assessments of the performance characteristics of metal-polymer (MP) plain bearings at the design stage are necessary and important for engineering practice. They include assessments of bearing capacity, linear wear of the bushing, and bearing life. However, no method for their calculation has been developed. The authors created a generalized analytical method for the mathematical modeling of MP sliding bearings as a classical science-based method to study the contact mechanics of conformal cylindrical bodies with consideration of polymer bushing wear. The contact problem of the theory of elasticity takes into account the significant difference in the elasticity characteristics of polymeric materials from those of steel: their Young’s modulus is 60–250 times smaller, and Poisson’s ratio is 1.27–1.37 times larger. The method was used to study MP bearings with bushings made from several common groups of tribopolymers: polyamides (PAs), polytetrafluoroethylenes (PTFEs), polyethylene terephthalates (PETs), and polyetheretherketones (PEEKs). The maximum contact pressures and durability of the dry friction bearings were calculated while taking into account the load; radial clearance; bushing thickness; the tribopolymers’ elasticity characteristics and wear resistance; the sliding friction coefficient; and the type of tribopolymer material. The Young’s modulus of a polymer material had a significant impact on the level of maximum contact pressures. Polymer fillers, depending on their type and the type of polymer, had very different effects on pressure changes (increase, no change, or decrease). An increase in pressure caused an increase in contact pressures. The durability of a mechanical bearing depended not only on the contact pressure but also on the polymer’s wear resistance, Young’s modulus, and friction coefficient. This study determined the quantitative and qualitative effects of these factors on the maximum contact pressures and bearing durability. The presented analytical method provides an effective and reasonable assessment of the specified service characteristics of sliding bearings with consideration of the multifactorial influence of the above factors.

Amyloid Nanofilm-Induced surface mineralization of 3D-Printed Polyetheretherketone scaffolds for in situ orbital bone regeneration and repair

Orbital bone defect repair is both challenging and crucial and requires the comprehensive consideration of anatomical complexity, functional preservation, aesthetic outcomes, postoperative risks, and long-term effects. Polyetheretherketone (PEEK) is a promising orthopedic substitute material due to its cortical bone-like elastic modulus, biocompatibility, chemical stability, and natural radiolucency. However, PEEK is bioinert and lacks interfacial bioactivity, which limits its ability to promote bone growth and osseointegration. In this study, we fabricated porous PEEK scaffolds using Fused Deposition Modeling (FDM) 3D printing technology. We employed a phase-transitioned lysozyme (PTL) nanofilm as the organic matrix template to construct a robust hydroxyapatite (HAp) coating both inside and outside the porous PEEK scaffold, generating HAp@PTL@PO-PEEK. The PTL nanofilm acted as a strong glue, enhancing the interfacial bonding strength between the HAp coating and PEEK. In vitro cell biology experiments revealed that HAp@PTL@PO-PEEK promoted the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells. Furthermore, the modified scaffolds exhibited excellent osteoconductivity and osteoinductivity in the in vivo repair of rabbit orbital bone defects, promoting new bone formation and guiding new bone growth into the scaffold. Therefore, HAp@PTL@PO-PEEK scaffolds hold potential for clinical craniomaxillofacial bone regeneration and repair.

Nanoscale Poly(Dopamine)‐Modified ZIF‐8 Particle Hybrid Solvent‐Resistant Thin Film Nanocomposite (TFN) Membranes via Interfacial Polymerization on a Robust Polyether Ether Ketone (PEEK) Substrate

ABSTRACTThis study introduces an innovative approach to fabricating a poly ether ketone (PEEK)‐based thin‐film nanocomposite (TFN) nanofiltration membrane. Ultrafine polydopamine (PDA) modified zeolitic imidazolate framework‐8 (ZIF‐8) nanoparticles were integrated into the polyamide (PA) layer through a process of interfacial polymerization. The impacts of PDA@ZIF‐8 nanoparticle loading on composite membranes were examined, and their separation performances with different solvents and small molecular organics with various molecular weights and charges were evaluated. The PDA modification is credited with inducing a thinner, less crosslinked PA layer, culminating in the formation of a selective barrier that is both loose and ultra‐thin, improving the separation capabilities of membranes. The TFN‐3 membrane, with a 0.01 wt% loading of PDA@ZIF‐8 nanoparticles, emerged as a standout, demonstrating notably enhanced hydrophilicity. The pure water and organic solvent permeances through the TFN‐3 membrane were remarkably enhanced, with recorded values of 6.19 ± 0.26 L h−1 m−2 bar−1 for pure water and 3.44 ± 0.21 L h−1 m−2 bar−1 for methanol. Furthermore, the TFN‐3 membrane showcased impressive molecular retention in ethanol solutions for compounds with a molecular weight cut‐off (MWCO) of 464 g/mol. The PEEK‐based TFN‐3 membrane also exhibited exceptional creep resistance, ensuring consistent performance during long‐term testing. In a 5‐day ethanol separation test, the TFN‐3 membrane maintained a Rose Bengal (RB) retention rate exceeding 99%, underscoring its stability and reliability. The newly developed PEEK‐based TFN membrane not only promises robust solvent resistance and stability but also delivers efficient separation and purification capabilities. It holds great potential for offering effective and sustainable solutions across a spectrum of industries, particularly in pharmaceutical production and chemical processing, where the separation, recovery, and purification of solvents are paramount.

Mechanical Behaviour of Additive Manufactured PEEK/HA Porous Structure for Orthopaedic Implants: Materials, Structures and Manufacturing Processes

Polyether-ether-ketone (PEEK) composites represent one of the most promising approaches to overcoming the weak osseointegration associated with the bioinertness of PEEK, making them highly suitable for clinical translation. Implants with porous structures fabricated by additive manufacturing offer the potential for long-term stability by promoting bone ingrowth. However, despite the importance of porous design, there is still no consensus on the optimal approach for PEEK-based composites. Given the significance of permeability and mechanical properties as functional indicators closely linked to osseointegration, the effects of material composition, structural design, and manufacturing processes on the permeability and mechanical properties of PEEK/hydroxyapatite (HA) scaffolds were systematically investigated in this study. In terms of permeability, the axial permeability of scaffolds with different pore sizes and representative volume elements varied within the range of 0.3-24.8 × 10-9 m2. Among scaffolds with similar relative density, the Gyroid structure exhibited the lowest permeability, while the orthogonal structure demonstrated the highest. For cylindrical scaffolds, circumferential permeability decreased with increasing penetration depth, suggesting a potential reduction in bone ingrowth speed with depth. As for mechanical properties, the experimentally determined effective elastic modulus and effective yield strength of the scaffolds ranged from 675.1 MPa to 65.2 MPa and 43.5 MPa to 4.1 MPa, respectively. The permeability and mechanical properties of PEEK/HA scaffolds with relative density ranging from 35-50% aligned with the those of human cancellous bone. By applying heat treatment at 240°C for 120 minutes, the crystallinity of PEEK increased to 37.2%, resulting in a substantial improvement in both the strength and stiffness of the scaffolds. However, excessive crystallinity led to brittle fracture, which in turn reduced the strength of the scaffolds. This study employed a systematic research approach to investigate how material composition, structural design, and manufacturing processes influence the mechanical properties and permeability of PEEK composite bone scaffolds, which are crucial for bone ingrowth. The results offered insights that support the design, manufacturing, and performance evaluation of PEEK-based porous implants.

Interfacial crystallization behavior and properties of T1100-grade carbon fiber reinforced PEEK composites

As a semi-crystalline resin, the crystallization behavior of Polyether ether ketone at the interface between carbon fiber and resin matrix profoundly affects the interfacial properties of carbon fiber-reinforced PEEK composite. Therefore, the research on the interfacial crystallization behavior of CF/PEEK composite is of great significance. Aiming at Chinese-made T1100-grade carbon fiber and PEEK resin matrix, the effects of cooling rate and sizing agent on the interfacial crystallization behavior of T1100-grade carbon fiber/PEEK were studied by POM and DSC, and the IFSS was tested by microdebond. The experimental results show that the increase of the cooling rate and the removal of the sizing agent can improve the nucleation ability of PEEK and promote the interfacial crystallization of PEEK. PEEK starts to form transcrystallization, when the nucleus density is increased to about 0.07/μm. The interfacial crystallization behavior has an effect on the interfacial properties. The IFSS increases with increasing cooling rate and removal of sizing agent.

Ultrasonic reconsolidation of separated CF-PEEK composite layers at 20 kHz — An experimental study on parameter optimization and Ex-situ characterization

Ultrasonic-assisted joining can replace the current repair strategies, such as adhesive bonding, to join the repair patches onto the damaged aerospace composite structures due to their energy and time efficiency. This work reports on the process optimization of repairing separated carbon fiber reinforced (CF)/ poly-ether-ether-ketone (PEEK) layers through ultrasonic reconsolidation at 20 kHz and its influence on the mechanical performance. The results showed that weld force and weld time dominate the temperature evolution, which was used to set the ultrasonic process window. Repairing CF-PEEK layers to different laminate architecture exhibited a 15% deviation from the reference repair. Compared with quantitative results, the ex-situ investigation showed that excessive holding force caused fiber–matrix debonding, leading to a cohesive failure inside the composite laminate. An optimal holding force, approximately 25% of the used weld force, is recommended to alleviate these damages.

Design of High-Performance Electrospun Membranes for Protective Clothing Applications.

The integration of nanomaterials into the textile industry has significantly advanced the development of high-performance fabrics, offering enhanced properties such as UV blocking, fire resistance, breathability, hydrophobicity, antimicrobial activity, and dust rejection. In this context, our research explores the development and characterization of electrospun membranes composed of polyether ether ketone (PEEK) and various polyimides (PIs (1-6)), focusing on their application in protective clothing. The combination of phosphorus-containing polyimides and PEEK, along with the electrospinning process, enhances the distinctive properties of both PEEK and polyimides, leading to composite membranes that stand out according to key parameters essential for maintaining physiological balance. The structural and morphological characteristics of these membranes have been evaluated using Fourier transform infrared spectroscopy (FTIR) to identify the functional groups and scanning electron microscopy (SEM) to examine their morphology. These analyses provide critical insights into these materials' properties, which influence key performance parameters such as moisture management, breathability, and barrier functions. The membranes' breathability and impermeability were assessed through the water vapor transmission rate (WVTR), contact angle measurements, water and air permeability, and flame resistance tests. The results obtained indicate that PEEK/polyimide composite membranes meet the complex requirements of modern protective textiles, ensuring both safety and comfort for users through their optimized structural properties and enhanced functional capabilities.

Volume and Distribution of Early Knee Effusion After TKA with a PEEK-Based Knee Prosthesis

Background: Early knee effusion is a common phenomenon after total knee arthroplasty (TKA), with potential clinical implications. Unlike traditional alloy knee prostheses, the polyetheretherketone (PEEK) knee system has radiographic transparency on magnetic resonance (MR) scans, which allows analysis of prosthetic knee effusion. We aimed to identify the distribution and volume of knee effusion after TKA with the PEEK prosthesis with use of MR imaging and to analyze whether dynamic changes in effusion were correlated with serum inflammatory marker changes and knee function recovery. Methods: Nine patients with osteoarthritis who were 59 to 74 years old underwent unilateral TKA with the PEEK prosthesis between June 2021 and August 2021. Dynamic early postoperative changes in the volume and distribution of knee effusion were evaluated with use of 3D MR stereoscopic images. Serum inflammatory markers were measured via blood tests, and joint function was evaluated with use of the subjective functional score of the Knee Society Score (KSS) and knee range of motion (ROM). Linear regression analyses were performed to assess for correlations between knee effusion volume and inflammatory markers and between knee effusion volume and joint function. Results: The mean serum inflammatory marker levels increased significantly at 1 week after TKA with the PEEK prosthesis and then gradually decreased with time from 1 to 6 months. The mean total knee effusion volume gradually decreased over time. Concurrently, the mean KSS subjective functional score and mean knee ROM improved with time. Total knee effusion volume was positively correlated with C-reactive protein level (R2 = 0.16; p = 0.007) and negatively correlated with the change in KSS score between the preoperative and postoperative time points (R2 = 0.19; p = 0.003). Using the 1-week total knee effusion volume as a reference, a positive correlation was observed between the reduction in total knee effusion volume and the actual value of the ROM (R2 = 0.36; p = 0.0001) from 3 to 24 months postoperatively. Conclusions: Through 3D MR imaging, the precise distribution and volume of, and dynamic changes in, knee effusion after TKA with the PEEK prosthesis were confirmed and were found to be correlated with inflammation and joint function in the early postoperative period. The results demonstrate the potential clinical benefit of the PEEK-based knee system for future use. Level of Evidence: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Biomineralized PEEK cages containing osteoinductive CaP bioceramics promote spinal fusion in goats

Interbody fusion devices are critical in spinal surgery to restore spinal stability, reduce pain and improve function. Polyetheretherketone (PEEK) has become a commonly used alternative material for fusion cages owing to its excellent mechanical properties and biocompatibility, but its biological inertness limits bone regeneration and may lead to poor fusion. In this study, a novel strategy for preparing bioactive biomineralized PEEK cages was developed using a unique combination of osteoinductive CaP bioceramic fillings in the cage window, acid sulfonation and simulated body fluid incubation. In vitro experiments showed that biomineralized PEEK cages and CaP bioceramics regulate immunity and promote angiogenesis and bone integration via activation of hypoxia-inducible factor 1-alpha and cyclic guanosine monophosphate/protein kinase G signaling pathways. In vivo goat spinal fusion experiments demonstrated that PEEK cages filled with CaP bioceramics resulted in good bone growth and spinal fusion. Therefore, the high mechanical strength and good biocompatibility of biomineralized PEEK cages, together with the excellent bioactivity and degradation properties of CaP bioceramics, provide an ideal microenvironment for bone fusion. The development of this composite material not only addresses some of the limitations of existing fusion devices but also will facilitate the development of spinal fusion technology.

Design and Verification of Continuous Tube Forming Process Parameters for PEEK-Based Rod Aimed at Space Manufacturing Applications

To meet the in-orbit construction needs of super-large spacecraft for ultra-long rod structures, this paper proposes an innovative on-orbit roll forming method for polyetheretherketone (PEEK)-based rod stock. This method ingeniously integrates temperature gradient control into a continuous deformation surface cavity design to achieve an efficient forming of resin rod components. A parametric model of the forming die cavity was established based on the comprehensive bending and downhill methods, and the boundary conditions for the temperature distribution gradient within the cavity were determined. Through the simulation and analysis of the PEEK rod curling and stitching forming process, the influence of the cavity configuration parameters on the forming load was determined. By constructing a test platform for the roll forming characteristics of resin rod components, the effects of different forming methods, stitching temperatures, and feed rates on forming quality and load were verified, and the main factors affecting the width of the welding zone, the roundness of the rod, and the straightness of the weld were analyzed. Experimental results show that the proposed continuous roll forming scheme can achieve an efficient and continuous forming of resin rod structures. When the length of the member is processed to 300 mm, at a formed rod diameter of 20 mm, by employing a cavity deformation zone length of 210 mm, a cavity clearance of 0.1 mm, a sheet width of 61 mm, a feed rate of 1 mm/s, and a sealing zone temperature setting of 335 °C, optimal rod forming quality can be achieved, characterized by a straightness error of 0.0133 ± 0.005 mm and a roundness error of 0.19 ± 0.07 mm. The proposal of this scheme provides a reliable basis for the continuous manufacturing of rod structures in the on-orbit construction of large space structures in terms of both the scheme and the parameter selection.

Fabrication and X-ray microtomography of sandwich-structured PEEK implants for skull defect repair

Bone defects pose a significant risk to human health. Medical polyetheretherketone (PEEK) is an excellent implant material for bone defect repair, but it faces the challenge of bone osteoconduction and osseointegration. Osteoconduction describes the process by which bone grows on the surface of the implant, while osseointegration is the stable anchoring of the implant achieved by direct contact between the bone and the implant. Bone defects repair depends on the implant’s three-dimensional spatial structure, including pore size, porosity, and interconnections to a great extent. However, it is challenging to fabricate the porous structures to meet specific requirements and to characterize them without causing damage. In this study, we designed and fabricated sandwich-like PEEK implants mimicking the three-layer structures of the skull, whose defects imposes a significant burden on young adulthood and paediatric populations, and performed in-line phase-contrast synchrotron X-ray microtomography to non-destructively investigate the internal porous microstructures. The sandwich-like three-layer microstructure, comprising a dense layer, a loose layer and a dense layer in succession, exhibits structural similarity to that in a natural skull. This work demonstrated the fabrication of the sandwich-like PEEK implant that could potentially enhance osteoconduction and osseointegration. Furthermore, the interior structures and residual porogen sodium chloride particles were observed within the PEEK implant, which cannot be realized by other microscopic methods without destroying the sample. It highlights the advantages and potential of using synchrotron X-ray microtomography to analyze the structure of biomedical materials. This study provides theoretical guidance for the further design and fabrication of PEEK bone repair materials and will advance the clinical application of innovative bioactive bone repair materials.

Investigating the Effect of Polyetheretherketone (PEEK) Veneers on Bond Strength and Discoloration When Repairing Various Composites

Investigating the Effect of Polyetheretherketone (PEEK) Veneers on Bond Strength and Discoloration When Repairing Various Composites

Mechanism and performance of thermal radiation recycling for in-space 3D printed continuous carbon fibre-reinforced PEEK composites

ABSTRACT The benefits of space recycling lie in reducing launch mass and achieving self-sufficiency. For 3D printed continuous fibre-reinforced composites (CFRCs), a reverse melt recycling technology was proposed, involving heating resin opposite to the 3D printing path and continuously peeling-off the fibres from the melt. An infrared radiation heating recycling device suitable for a vacuum environment was designed and the temperature distributions were optimised, achieving recycling of continuous carbon fibre-reinforced polyether ether ketone (CF/PEEK) thin-walled rotational structures. The recycled filaments with diameters of 0.7 and 0.8 mm could achieve good surface quality and low pore defects. The porosity decreased from 11.2% of original samples to 5.7% of remanufactured samples, leading to improvements in mechanical properties with flexural strength and modulus increased by 4.8% and 50.8% respectively. Overall, the recycling technology emphasised a non-degradation recycling solution for 3D-printed CFRCs in space to form a full lifecycle application model for space composites.

Powder casting of polyetheretherketone and polyphenylene sulfone: Sintering

Systematic studies of the influence of the basic powder characteristics and its sintering conditions on the physical and mechanical properties of samples intended for the implementation of the technology of powder injection molding of products from typical heat-resistant high performance engineering polymers - crystallizing polyetheretherketone (PEEK) and amorphous polyphenylene sulfone (PPSu) - were carried out. Polymers with different MW were synthesized as initial materials and powders with different sizes and bulk density were obtained. The influence of these parameters on the nature of powder sinterability and, as a consequence, on their elastic modulus and tensile strength was shown. Optimum characteristics for bulk density and sintering temperature were established, which provide maximum values of mechanical characteristics of the molded samples. The results of the fundamental research conducted allowed us to produce two typical products for biomedicine - an intervertebral cage (an implant replacing a removed vertebra) and a blood dialyzer part.

Mechanical and surface characterisation of additively manufactured polyetheretherketone for the tribo test

Purpose The additive manufacturing process, such as fused filament fabrication based on material extrusion, fabricates the samples layer-by-layer. The various parameters in the process significantly affect the dimensions, structure and mechanical properties of the fabricated parts. The purpose of this paper is to investigate the surface and mechanical properties that can affect the contact characteristics with other materials during tribological tests. Design/methodology/approach The investigation of 3D-printed Polyetheretherketone (PEEK) includes the measurement of dimensions, microhardness, surface roughness, surface energy and tensile strength to define material characteristics. The crystallinity is measured using an X-ray diffractometer to understand the hardness behaviour. Findings The printing parameters affect its surface roughness, hardness and crystallinity. This change in parameters such as layer thickness and infill density impacts mechanical properties such as hardness and surface roughness, which will influence the contact mechanism with the counter body during any tribological test. The change in a single parameter during the sample fabrication and the change in the surface and mechanical properties are observed. Research limitations/implications The material cost plays an important role in conducting numerous destructive tests, which is a major limitation to conducting parameter optimisation by varying more parameters. The study is limited to the as-fabricated samples rather than finished samples and without any heat treatment. Achieving optimal parameters is integral to the success of additive manufacturing, ensuring the production of components with consistent performance. Practical implications The study aims at the application of 3D-printed PEEK for bush or journal bearings that can be directly used in practice. The mechanical properties discussed in this paper can fill the gap between theory and practice. Social implications The research provides all fundamental properties, including the printing parameters and their effect on the dimensions and surface structure, which are required to understand the material and its use. The results are consistent as at least four samples were tested for tribological behaviour. The conclusion is updated as per suggestions. Originality/value The study outlines the relationship between the change in layer thickness and infill density with changes in surface energy, surface roughness, hardness and tensile strength. The deformation and adhesion during the friction test depend on these properties.

Investigations of the Interface Design of Polyetheretherketone Filament Yarn Considering Plasma Torch Treatment

Taking advantage of its high-temperature resistance and elongation properties, conductive-coated polyetheretherketone (PEEK) filament yarn can be used as a textile-based electroconductive functional element, in particular as a strain sensor. This study describes the development of electrical conductivity on an inert PEEK filament surface by the deposition of metallic nickel (Ni) layers via an electroless galvanic plating process. To enhance the adhesion properties of the nickel layer, both PEEK multifilament and monofilament yarn surfaces were metalized by plasma torch pretreatment, followed by nickel plating. Electrical characterizations indicate the potential of nickel-coated PEEK for structural monitoring in textile-reinforced composites. In addition, surface energy measurements before and after plasma torch pretreatment, surface morphology, nickel layer thickness, chemical structure changes, and mechanical properties were analyzed and compared with untreated PEEK. The thickness of the Ni layer was measured and showed an average thickness of 1.25 µm for the multifilament yarn and 3.36 µm for the monofilament yarn. FTIR analysis confirmed the presence of new functional groups on the PEEK surface after plasma torch pretreatment, indicating a successful modification of the surface chemistry. Mechanical testing showed an increase in tensile strength after plasma torch pretreatment but a decrease after nickel plating. In conclusion, this study successfully developed conductive PEEK yarns through plasma torch pretreatment and nickel plating.

Assessments and investigation of process parameter impacts on surface roughness, microstructure, tensile strength, and porosity of 3D printed polyetherether ketone (PEEK) materials

Additive manufacturing (AM) is emerging as a competitive technology with promising applications across various sectors, including biomedical, automotive, construction, and dental implants. This study investigates the influence of key process parameters on the surface roughness, microstructure, tensile strength, and porosity of Polyether Ether Ketone (PEEK), a high-performance thermoplastic used in dental prosthetics. Traditionally, metals and ceramics have been the standard for dental restorations, but advancements in computer-aided design (CAD) and computer-aided manufacturing (CAM) have improved accuracy, particularly for implant-supported prostheses. However, conventional methods like CAD-milling face challenges such as material waste and tool wear. AM techniques, such as fused deposition modeling (FDM), offer a solution by constructing objects layer by layer, minimizing waste. This research explores the effects of nozzle temperature on the mechanical properties of 3D-printed PEEK, emphasizing its role in optimizing performance and minimizing issues like porosity. Key factors like surface roughness and microstructure are highlighted as critical to the biocompatibility and longevity of dental restorations. The study identifies the optimal nozzle temperature range for PEEK 380–440 °C, noting that deviations from this range lead to compromised mechanical properties. Overall, the findings provide valuable insights into optimizing the AM process for PEEK in dental applications and suggest that further biological and chemical studies are necessary to fully realize the material's potential in replacing traditional dental restoration materials.

Effects of various laser applications on surface roughness and bond strength to veneering composites of polyether ether ketone (PEEK) and polyether ketone ketone (PEKK) materials.

The aim of this study was to investigate the bond strength between PEEK/PEKK and composite resins after various laser treatments and to compare the effectiveness of lasers on these polymers. 130 disc-shaped PEEK and PEKK blocks were obtained (10mm diameter-4mm height). One sample from each group (10 in total) was selected for scanning electron microscopy (SEM) analysis. The samples were randomly divided into 5 different surface treatment groups for each material (PEEK and PEKK): Er: YAG laser, Nd: YAG laser, diode laser, femtosecond laser and control (no surface treatment) (n = 12). Baseline and post-treatment surface roughness measurements were performed using a profilometer. The composite resin was bonded and SBS was measured. Comparisons among the groups were conducted via Kruskal-Wallis, one-way ANOVA; Tukey and Dunn tests were used as a post hoc test (p ≤ 0.05). All lasers significantly increased the roughness values of the PEEK and PEKK samples. In terms of shear bond strength; the Er: YAG and femtosecond laser groups had the highest values and the Nd: YAG, diode and control groups had the lowest values of the PEEK samples (p ≤ 0.05). The control group had the highest bond strength values and the femtosecond group had the lowest values for PEKK samples (p ≤ 0.05). All laser treatments increased the surface roughness of the PEEK and PEKK. Lasers increased the bond strength of PEEK to the veneering composite resin and decreased the bond strength values of PEKK. This shows that lasers behave differently in PEEK and PEKK materials.

Facile Depolymerization of Thermally Stable Polyetherethersulfone and Polyetheretherketone Using Hydroquinone and Bases.

Super engineering plastics such as polyetheretherketone (PEEK) and polyetherethersulfone (PEES) exhibit thermal stability, chemical resistance, and mechanical strength. Such characteristics are attributed to their robust chemical structures composed of stable aryl ethers. These features make chemical recycling difficult. This is because it is necessary to overcome through the stability of the material and then precisely cleave the stable bonds. This study demonstrates the depolymerization of PEES and PEEK by hydroquinone in the presence of sodium hydroxide in 1,3-dimethyl-2-imidazolidinone (DMI) solvent at 150 °C. This method effectively provides monomeric products, diphenylsulfone and benzophenone having two 4-hydroxyphenoxy groups at both para positions. DMI solvent was the crucial factor for this transformation, since it enhanced the reactivity of hydroquinone to cleave the aryl ether bonds.

“Janus” PEEK implant with sandwich Mg-containing coating for infected tissue repair

Having good antibacterial properties and promoting soft and hard tissue repair are the keys to successful implantation of intraosseous transcutaneous. Polyether ether ketone (PEEK) is a class of FDA-approved polymer implants. However, the surface of PEEK is bioinert, which is easy to cause postoperative infection and poor tissue integration. In this study, polypyrrole (Ppy) was polymerized on sulfonated PEEK, Mg3(PO4)2 nanosheets were grown in situ on one side, and polycaprolactone (PCL) was then spun on the surface to form a Janus-like surface on PEEK. The Ppy/Mg3(PO4)2/PCL composite coating could inhibit bacterial adhesion, and the excellent photothermal properties of Ppy/Mg3(PO4)2/PCL and Ppy coatings further promote the removal of bacteria due to the accumulated heat. After the infection was eliminated, the Janus-like surface of modified PEEK switched macrophages to anti-proinflammatory response and promoted both soft and hard tissue repair. The Ppy modified sulfonated PEEK could promote collagen secretion in the soft tissue, while the PCL films on Ppy/Mg3(PO4)2/PCL was densified by temperature response under near-infrared light treatment to close the exposed interface of Mg3(PO4)2 nanosheets that was more conducive to bone repair. In summary, PEEK with Janus-like surface consisting of Ppy/Mg3(PO4)2/PCL and Ppy has multiple biological functions of sequential antibacterial and soft and hard tissue repair, and is a promising candidate material for intraosseous transcutaneous implants.