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Poly(ether ether ketone) (PEEK) is a biocompatible polymer, but the lack of angiogenesis makes the long-term osteogenic fixation of PEEK implants challenging, which has hampered their wider application in orthopedics. Herein, we develop a multifunctional micro-/nanostructured surface presenting hydroxyapatite (HA) nanoflowers and nickel hydroxide (Ni(OH) 2 ) nanoparticles on PEEK implants (sPEEK-Ni-HA) to tackle the problem. The results show that the reasonable release of Ni 2+ from sPEEK-Ni-HA significantly facilitates the migration, tube formation, and angiogenic gene expression of human umbilical vein endothelial cells (HUVECs). In addition to angiogenesis, the sPEEK-Ni-HA displays enhanced cytocompatibility and osteogenicity in terms of cell proliferation, spreading, alkaline phosphatase activity, matrix mineralization, and osteogenesis-related gene secretion, exceeding pure and other multifunctional sPEEK samples. Importantly, in vivo evaluations employing a rabbit femoral condyle implantation model confirm that such dual decoration of Ni elements and HA nanoflowers boosts bone remodeling/osseointegration, which dramatically promotes the in vivo osteogenic fixation of implants. Therefore, this work not only sheds light on the significance of angiogenesis on the osteogenic fixation of an implant but also presents a facile strategy to empower bioinert PEEK with a well-orchestrated feature of angiogenesis and osteogenesis.

Biomedical applications of poly(ether ether ketone) (PEEK) are hindered by its inherent bioinertness and lack of osseointegration capability. In the present study, to enhance osteogenic activity and, hence, the osseointegration capability of PEEK, we proposed a strategy of combined phosphate and calcium surface-functionalization, in which ozone-gas treatment and wet chemistry were used for introduction of hydroxyl groups and modification of phosphate and/or calcium, respectively. Surface functionalization significantly elevated the surface hydrophilicity without changing the surface roughness or topography. The cell study demonstrated that immobilization of phosphate or calcium increased the osteogenesis of rat mesenchymal stem cells compared with bare PEEK, including cell proliferation, alkaline phosphatase activity, and bone-like nodule formation. Interestingly, further enhancement was observed for samples co-immobilized with phosphate and calcium. Furthermore, in the animal study, phosphate and calcium co-functionalized PEEK demonstrated significantly enhanced osseointegration, as revealed by a greater direct bone-to-implant contact ratio and bond strength between the bone and implant than unfunctionalized and phosphate-functionalized PEEK, which paves the way for the orthopedic and dental application of PEEK.

Poly(ether ether ketone) (PEEK) is an alternative material to metals for orthopedic applications. However, the compatibility of PEEK with hard tissues needs to be improved. To address this issue, this study proposes a novel technique for PEEK surface modifications. A polyphosphodiester macromonomer (PEPMA·Na) was synthesized via the demethylation of polyphosphotriester macromonomer obtained via the ring-opening polymerization of cyclic phosphoesters using 2-hydroxypropyl methacrylamide as the initiator. The surface modification of PEEK was performed via photoinduced and self-initiated graft polymerization of PEPMA·Na without using any photoinitiators. The amount of phosphorus due to poly(PEPMA·Na) immobilized on PEEK increased with an increase in the photoirradiation time. The PEEK surface turned hydrophilic due to poly(PEPMA·Na) grafting, with almost similar advancing and receding contact angles, implying that the modified PEEK surface (PEEK-g-poly(PEPMA·Na)) was homogeneous. Specimens were mineral coated by simple static soaking in ×1.5 simulated body fluid (1.5SBF) and by an alternative process that included additional soaking steps in 200 mM CaCl 2 aq. and 200 mM K 2 HPO 4 aq. before static soaking in 1.5SBF. Specimens were immersed in 1.5SBF for 28 days in simple static soaking, after which the PEEK-g-poly(PEPMA·Na) surface was completely covered with spherical cauliflower-like mineral deposits that resembled octacalcium phosphate (OCP). Their structural similarities were confirmed via X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), and X-ray fluorescence (XRF) analyses. However, these mineral deposits were not observed on the bare PEEK surface. Due to the additional soaking steps (alternative soaking) undertaken before the static soaking of the specimens in 1.5SBF, the mineral coating on the PEEK-g-poly(PEPMA·Na) was dramatically accelerated and the surface was fully covered with mineral deposits in only one day of soaking. The mineral deposits resulting from both the soaking processes had similar structures. Compared with bare PEEK, osteoblastic MC3T3-E1 cells proliferated more actively on mineral-coated PEEK-g-poly(PEPMA·Na). Thus, the surface immobilization of poly(PEPMA·Na) on a PEEK surface is effective for mineral coating and may be useful to provide hard-tissue compatibility on PEEK.

Nonaqueous capillary electrophoresis (CE) and organic-aqueous CE using high content of organic solvents are common techniques in capillary electrophoresis-mass spectrometry (CE-MS) due to various advantages. However, the long-term stability of commonly used polyimide coated fused silica capillary remains a major problem that polyimide coating is prone to swelling in organic solvents and aminolysis in alkaline buffer, which cause serious problems like irregular electrospray, current drop or clogging event. In this work, robust PEEK capillary was used as separation capillary for tolerance to high content of organic solvents in CE-MS system. It is interesting that the high mechanical and chemical stability of PEEK capillary ensured stable CE separation and electrospray when used in CE-MS. All quantitative experiments were accomplished by single PEEK capillary. In addition, the using of organic solvents as running buffer reduced adsorption of hydrophobic compounds on PEEK capillary wall and improved the symmetry of peak shape. The PEEK-based CE-MS method showed good separation performance in analysis of several groups of active alkaloids in traditional Chinese medicines and was applied for quantitative analysis of peimine and peiminine in Bulbus Fritillariae thunbergii herb with high sensitivity. Based on the advantages like simple pretreatment, easy to cut, stable and good separation performance of PEEK column in CE-MS, this study provides an effective way for improving the stability and employment of high content of organic solvents in CE-MS analysis., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Improved thromboresistance of mechanical valves is desired to decrease the risk of thromboembolism and thrombosis and reduce the dosage of anticoagulation with a vitamin K antagonist (e.g., warfarin). For several mechanical valves, design-related features are responsible for their improved thromboresistance. However, it remains unclear whether material-related features provide a practical level of thromboresistance to mechanical valves. Here, we studied the effect of a bileaflet valve made of poly(ether ether ketone) (PEEK) with a poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC)-grafted surface (PEEK-g-PMPC). PMPC is a well-known thromboresistant polymeric material. A short-term (<26 h) porcine aortic valve replacement model using neither an anticoagulant nor an antiplatelet agent showed that the PEEK-g-PMPC valve opened and closed normally with an allowable transvalvular gradient. Unlike an untreated PEEK valve, no thrombus formed on the PEEK-g-PMPC valves on gross anatomy examination in addition to the absence of traveled thrombi in the kidney and lung tissues. Material (PEEK-g-PMPC)-related thromboresistance appeared to decrease the risk of thromboembolism and thrombosis for patients with mechanical valves. However, thromboresistance of the PEEK-g-PMPC valve requires improvement because fibrous fouling was still observed on the leaflet. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1052-1063, 2019., (© 2019 Wiley Periodicals, Inc.)

Preparation of stir bar extraction (SBSE) device with high physical and chemical stability is important and challenging by date. A novel poly (ether ether ketone) (PEEK) tube with excellent mechanical property and chemical stability was firstly used as jacket of metal bar for preparation of stir bar. By employing covalent modification method, the inherent chemical resistant problem of PEEK which restricts the modification of sorbents was well solved. After functionalization, plenty of benzoic acid groups were formed onto the PEEK jacket. Metal organic frameworks of aluminium-based Materials of Institute Lavoisier-68 (MIL-68) was in situ immobilized onto the PEEK surface (MIL-68@PEEK) by the bonding with benzoic acid groups. Afterwards, a facile dumbbell-shaped structure was designed for reducing the friction between sorbents and bottom of container. Due to superior property of the PEEK jacket and the covalent modification method, the MIL-68 modified PEEK jacket SBSE device showed good robustness. After coupling with HPLC-MS/MS, the MIL-68@PEEK-based SBSE device was used to analyse of three parabens including methyl paraben, ethyl paraben and propyl paraben. The method had low limit detection up to 1 pg mL -1 with good linearity (R 2  ≥ 0.9978) and good reproducibility (relative standard deviation ≤ 9.74%). The method has been applied to the detection of parabens in cosmetics and rabbit plasma after painted with cosmetics with recoveries between 73.25% and 104.23%., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Unlabelled: A highly efficient methodology for preparing a poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer on the surface of poly(ether ether ketone) (PEEK) was examined by photoinduced and self-initiated graft polymerization. To enhance the polymerization rate, we demonstrated the effects of inorganic salt additives in the feed monomer solution on thickness of grafted PMPC layer. Photoinduced polymerization occurred and the PMPC graft layer was successfully formed on the PEEK surface, regardless of inorganic salt additives. Moreover, it was clearly observed that the addition of inorganic salt enhanced the grafting thickness of PMPC layer on the surface even when the photoirradiation time was shortened. The addition of inorganic salt additives in the feed monomer solution enhanced the polymerization rate of MPC and resulted in thicker PMPC layers. In particular, we evaluated the effect of NaCl concentration and how this affected the polymerization rate and layer thickness. We considered that this phenomenon was due to the hydration of ions in the feed monomer solution and subsequent apparent increase in the MPC concentration. A PMPC layer with over 100-nm-thick, which was prepared by 5-min photoirradiation in 2.5mol/L inorganic salt aqueous solution, showed good wettability and protein adsorption resistance compared to that of untreated PEEK. Hence, we concluded that the addition of NaCl into the MPC feed solution would be a convenient and efficient method for preparing a graft layer on PEEK., Statement of Significance: Photoinduced and self-initiated graft polymerization on the PEEK surface is one of the several methodologies available for functionalization. However, in comparison with free-radical polymerization, the efficiency of polymerization at the solid-liquid interface is limited. Enhancement of the polymerization rate for grafting could solve the problem. In this study, we observed the acceleration of the polymerization rate of MPC in an aqueous solution by the addition of inorganic salt. The salt itself did not show any adverse effects on the radical polymerization; however, the apparent concentration of the monomer in feed may be increased due to the hydration of ions attributed to salt additives. We could obtain PMPC-grafted PEEK with sufficient PMPC thickness to obtain good functionality with only 5-min photoirradiation by using 2.5mol/L NaCl in the feed solution., (Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Aromatic poly(ether ether ketone) (PEEK) is a super engineering plastic, which has good mechanical properties and is resistant to physical and chemical stimuli. We have, therefore, attempted to use PEEK in cardiovascular devices. Synthetic cardiovascular devices require both high hemocompatibility and anti-inflammatory activity in addition to the mechanical properties. We modified the PEEK surface by photoinduced and self-initiated graft polymerization with 2-methacryloyloxyethyl phosphorylcholine (MPC; PMPC-grafted PEEK) for obtaining good antithrombogenicity. Polymerization was carried out on the surface of PEEK under radiation of ultraviolet (UV) light during which we controlled monomer concentrations, temperatures, and UV intensities. The biological performance of the PMPC-grafted PEEK was examined and compared with that of unmodified PEEK. With increase in the thickness of the PMPC layer, the amount of fibrinogen adsorption decreased significantly in comparison to that in the case of unmodified PEEK. When placed in contact with human platelet-rich plasma, surface of the PMPC-grafted PEEK clearly showed inhibition of platelet adhesion and activation. Also, bacterial adhesion was reduced dramatically on the PMPC-grafted PEEK. Thus, the PMPC grafting on PEEK improved the antithrombogenicity., (Copyright © 2013 Wiley Periodicals, Inc.)

Black absorber with wide‐angle high absorption properties is of great significance to the in‐orbit operation of space optical system. However, up to now, black absorber used in space optical system with wide‐angle high absorption properties has rarely been reported. Herein, this work reports a multiscale structure coordinated black poly(ether ether ketone) (PEEK)‐based black absorber with lightweight, low volatilization, and wide‐angle high absorption properties through 3D printing method. The as‐prepared absorber with honeycomb structure shows a high surface absorptivity (about 96.89%), and excellent wide‐angle high absorption properties which absorptivity attenuation rate is only 1.43% at 70°, benefiting from 3D‐printed honeycomb structure and multi‐scale light trap structure on the absorber inner surface. Besides, high and low temperature cycling test shows that its wide‐angle high absorption properties have a good stability at the space extreme environment, and its collected volatile condensable material (CVCM) is as low as 0.00%. This work provides a new strategy for simple fabrication method of novel lightweight multifunctional‐structure integrated absorber for space optical system. [ABSTRACT FROM AUTHOR]

Most of the current poly(ether ether ketone) (PEEK) parts manufactured via fused deposition modeling (FDM) printing are suffering for weak interlayer adhesion and low mechanical strength. Herein, a simplified tactic is adopted, which combined FDM printing with annealing post-treatment, to realize a better mechanical strength, interlayer adhesion and wear resistance of 3D printed PEEK. The freeze-fracture surface of PEEK annealed at 190 ℃ was dense. At the normal load of 30 N, the wear rate of annealed PEEK reached the minimum value of 2.83 × 10−5 mm3/(N·m), with a 34 % reduction. At a higher load of 70 N, the annealed PEEK at 170 ℃ still maintained a low wear rate. Moreover, the annealed PEEK exhibited excellent manufacturing precision and fidelity. The PEEK annealed at 170 ℃ was used to simulate wear within knee-joint cavity and planetary gears were printed for demonstration, which run stably at different working conditions. These findings highlight the significant potential of 3D printed PEEK combined with annealing post-treatment in the applications of heavy-load gear and bionic joint. [Display omitted] • A strong and dense 3D printed PEEK is realized by combining FDM with annealing treatment. • The wear resistance of PEEK is improved with increasing annealing temperature. • Annealed PEEK exhibits excellent precision and fidelity in manufacturing the gear and bionic joint. [ABSTRACT FROM AUTHOR]

With the global effort to reduce fossil fuels and to use eco-friendly energy, interest in Li-ion batteries (LIBs) is rapidly increasing. In the LIB system, the separator is an important component for determining the rate performance and safety of cells. Although polyolefin separators are commercially used in LIBs, they still suffer from inferior electrolyte wettability and low thermal stability issues. Here, we introduce a chemical surface modification for polyethylene (PE) separators using a poly(ether ether ketone) (PEEK) coating. The separators were pretreated in a tannic acid solution to enforce the adhesion of the coated layers. Then, PEEK was coated onto the PE surface by a doctor blading method. The separators were examined by infrared spectroscopy, and the surface properties were characterized by electrolyte uptake and contact angle measurements. The treated surface was hydrophilic, and the ionic conductivity of the cell with the modified separator was significantly improved. As a result, the corresponding rate performance was significantly improved. The surface modification strategy proposed here can be applied to polyolefin-based separators as well. [ABSTRACT FROM AUTHOR]

The thermoelectric properties, at temperatures from 30 °C to 100 °C, of melt-processed poly(ether ether ketone) (PEEK) composites prepared with 10 wt.% of carbon nanofibers (CNFs) are discussed in this work. At 30 °C, the PEEK/CNF composites show an electrical conductivity (σ) of ~27 S m−1 and a Seebeck coefficient (S) of −3.4 μV K−1, which means that their majority charge carriers are electrons. The origin of this negative Seebeck is deduced because of the impurities present in the as-received CNFs, which may cause sharply varying and localized states at approximately 0.086 eV above the Fermi energy level (EF) of CNFs. Moreover, the lower S, in absolute value, found in PEEK/CNF composites, when compared with the S of as-received CNFs (−5.3 μV K−1), is attributed to a slight electron withdrawing from the external layers of CNFs by the PEEK matrix. At temperatures from 30 °C to 100 °C, the σ (T) of PEEK/CNF composites, in contrast to the σ (T) of as-received CNFs, shows a negative temperature effect, understood through the 3D variable-range hopping (VRH) model, as a thermally activated hopping mechanism across a random network of potential wells. Moreover, their nonlinear S (T) follows the same behavior reported before for polypropylene composites melt-processed with similar CNFs at the same interval of temperatures. [ABSTRACT FROM AUTHOR]

Sulfonation of poly(ether ether ketone) (PEEK) is an electrophilic substitution reaction that takes place on the aromatic ring flanked by the two ether groups. The degree of sulfonation (DS) reached up to 100% with only one sulfone group is attached to the activated aromatic rings. In the present work, a spectroscopic evidence for the attachment of a second sulfone group on the para position rather the meta position with respect to the first sulfone group in the activated ring is provided. With the help of 1H-, 13C- nuclear magnetic resonance (NMR) and two-dimensional correlation (2D-COS) spectroscopies, it was possible to show that the intensity of the proton in the para position with respect to the newly introduced sulfone group changed before the proton in the meta position with increasing DS. Further evidence was obtained from the analysis of 2D-NMR spectra namely; 1H-1H correlation spectroscopy (1H-1H-COSY), 1H-13C heteronuclear single quantum coherence spectroscopy (1H-13C-HSQC) and 1H-13C heteronuclear multiple bond correlation spectroscopy (1H-13C-HMBC) of highly sulfonated PEEK by the disappearance of proton 12' and the confirmation of the presence of other protons, i.e. 10' and 13'. 2D-COS is a powerful tool to analyze NMR spectra and extract information related to the structure of final products of complicated reactions such as sulfonation of polymers. [ABSTRACT FROM AUTHOR]

This paper introduced the properties of six high-performance resins, including poly(ether ether ketone) (PEEK), poly(phenylene sulfide) (PPS), liquid crystal polymer(LCP), poly(etherimide) (PEI), polysulfone(PSF), and polyimide (PI). The preparation processes and modification methods of the films based on these six respective resins were discussed in detail, and their applications were prospected. [ABSTRACT FROM AUTHOR]

The poly(ether ether ketone) (PEEK) was prepared as organic matrix. ZIF-8 and GO/ZIF-8 were used as fillers. A series of novel new anion exchange membranes (AEMs) were fabricated with imidazole functionalized PEEK and GO/ZIF-8. The structure of ZIF-8, GO/ZIF-8 and polymers are verified by 1H NMR, FT-IR and SEM. This series of hybrid membranes showed good thermal stability, mechanical properties and alkaline stability. The ionic conductivities of hybrid membranes are in the range of 39.38 mS cm−1–43.64 mS cm−1 at 30 °C, 100% RH and 59.21 mS cm−1–86.87 mS cm−1 at 80 °C, 100% RH, respectively. Im-PEEK/GO/ZIF-8-1% which means the mass percent of GO/ZIF-8 compound in Im-PEEK polymers is 1%, showed the higher ionic conductivity of 86.87 mS cm−1 at 80 °C and tensile strength (38.21 MPa) than that of pure membrane (59.21 mS cm−1 at 80 °C and 19.47 MPa). After alkaline treatment (in 2 M NaOH solution at 60 °C for 400 h), the ionic conductivity of Im-PEEK/GO/ZIF-8-1% could also maintain 92.01% of the original ionic conductivity. The results show that hybrid membranes possess the ability to coordinate trade-off effect between ionic conductivity and alkaline stability of anion exchange membranes. The excellent performances make this series of hybrid membranes become good candidate for application as AEMs in fuel cells. [Display omitted] • The hybrid AEMs showed good dimensional stability and excellent alkaline stability. • GO were conducive to ion transport and the construction of ion transport channels. • The imidazole groups in ZIF-8 could effectively increase content of "bulk water". [ABSTRACT FROM AUTHOR]

High‐performance engineering polymers continually challenge existing boundaries of rapidly emerging research areas including electronics, transportation, energy, defense and aerospace. Significant research attention over the past decade highlights the exceptional performance of these polymers due to their superior thermomechanical properties and stability under extreme conditions. Unfortunately, inherent structure–property relationships of high‐performance engineering polymers, which predict this unique complement of physical properties, also describe high‐viscosity melts and high melting temperatures. These processing challenges have steered researchers towards advanced processing methods, such as additive manufacturing, that allow for unprecedented control over part geometry. In addition, additive manufacturing serves to advance application–cost relationships, as part optimization and 3D printing of previous monolithic components allow for less material consumption. Currently, the additive manufacturing materials toolbox only contains a fraction of commercially available high‐performance polymers due to unique processing constraints. This review discusses recent efforts towards the successful additive manufacturing of three high‐performance polymer families, i.e. polysulfones, poly(ether ether ketone)s and polyimides. © 2021 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Glass fiber/poly(ether ether ketone) (GF/PEEK) composite foams with improved compressive strength and heat resistance can be successfully prepared using a simple and environmentally friendly supercritical carbon dioxide (sc‐CO2) foaming technology. The cell morphologies of the foams can be controlled by adjusting the GF content and foaming parameters, including the saturation temperature, saturation time, saturation pressure, and depressurization rate. With a foam density of 0.55 g cm−3, the PEEK‐based composite foam having 30% GF content has a 10% compressive strength of 11.07 MPa, and its density varies negligibly up to 330.0 °C. The GF/PEEK composite foams having high GF contents show significantly better properties than those having low GF contents as a result of the supporting and strengthening effect of the GF in the PEEK cell walls. The GF/PEEK composite foams also show good corrosion resistance. As a result of these properties, the GF/PEEK composite foams are promising high‐performance materials for use in extreme environments. [ABSTRACT FROM AUTHOR]

To improve the antifouling properties of poly(ether ether ketone) (PEEK) membrane, negatively charged acrylic acid (AA), neutral ethyl hydroxyacrylate (HEA) and positively charged acryloxyethyl trimethylammonium chloride (DAC) as hydrophilic monomers were respectively grafted onto the PEEK hollow fiber membrane surface via ultraviolet irradiation polymerization. The effects of the grafted monomers on surface chemical structure, surface morphology, zeta potential, hydrophilic performance, permeability and the antifouling properties of the membrane were investigated in detail. The results show that the charge state of the membrane surface is closer to the monomer charge characteristic, which obviously affects the permeability and antifouling performance of the membrane. The pure water flux of the membrane grafted with neutral hydrophilic HEA monomer is increased and the antifouling properties to bovine serum albumin (BSA) and sodium alginate (SA) are also enhanced, while the pure water flux of the membranes grafted with negatively charged AA monomer or positively charged DAC monomer is decreased, with different antifouling properties to BSA and SA. Furthermore, the antifouling experiment with BSA under different pH conditions revealed that membrane fouling depends on the pH value, and membrane fouling was the most serious at the isoelectric point of BSA. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Poly(ether ether ketone) (PEEK) is a high-performance thermoplastic used for several industrial applications due to its excellent mechanical properties. However, the use of PEEK is limited to dental materials because of its poor implant-bone integration. In the present study, methylated polyrotaxanes (MePRXs) with 4-vinylbenzyl groups, which are supermolecules composed of methylated α-cyclodextrins and poly(ethylene glycol) chains end-capped with 4-vinylbenzyl groups, were covalently tethered onto PEEK surfaces using photo-induced polymerization to improve their osteoblast compatibility. The surface-tethering of MePRXs onto PEEK surfaces was confirmed by analyzing their attenuated total reflectance Fourier transform infrared spectra and contact angles. When mouse preosteoblasts were cultured on the MePRX-PEEK and bare PEEK surfaces, the MePRX-PEEK surfaces showed significantly better proliferation and osteoblast differentiation than the bare PEEK surfaces. These results suggest that surface modification of PEEKs using MePRXs improves their osteoblast compatibility. [ABSTRACT FROM AUTHOR]

This study investigates the effect of pre-coating with methyl methacrylate (MMA) containing ultraviolet (UV) photoinitiators on the bond strength of poly(ether ether ketone) (PEEK). Cylindrical PEEK blocks were irradiated with 365 nm UV light for 5–20 s after they were coated with MMA containing 0.4–3.0 wt% UV photoinitiators: [1-phenyl-1,2-propanedione (PPD)], [diphenyl(2,4,6- trimethylbenzoyl) (TMDPO)], and [phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (BTMPO)]. Pre-coated PEEKs were bonded to PEEK blocks with a MMA-based adhesive resin. The shear bond strength was measured using a universal testing machine. Secondary electron images were captured to observe failure surfaces. The data were analyzed with one- and two-way ANOVA and Tukey’s post hoc tests (p<0.05). The highest bond strength (20.7±5.1 MPa) was observed for pre-coating with MMA containing 0.4 wt% BTMPO, for 20 s of UV irradiation. Cohesive failure of the adhesive resin was observed. The use of this pre-coating led to improved bonding performance of PEEK. [ABSTRACT FROM AUTHOR]

A series of quaternary ammonium salt poly(ether ether ketone) AEMs containing long ether substituents are successfully prepared, and their chemical structure is confirmed by 1H NMR and FT-IR. The distinct microphase separation morphology of AEMs is observed by TEM. As the content of methylhydroquinone increases, the ion conductivity of AEMs gradually increases. When the content of methylhydroquinone increases to 80%, the hydroxide conductivity of PEEK-DABDA-80 membrane reaches 0.052 S/cm at 80 °C. Meanwhile, it exhibits excellent mechanical properties and anti-swelling ability, with tensile strength of 25 MPa, elongation at break of 8.12% and swelling ratio is only 17.4% at 80 °C. And AEMs also display the better thermal stability. After soaked in 1 M NaOH at 60 °C for 30 days, PEEK-DABDA-80 membrane shows acceptable ion conductivity of 0.021 S/cm at 60 °C. In view of these properties, PEEK-DABDA-x AEMs may display potential application as alkaline AEMs. Image 1 • A series of poly(ether ether ketone) anion exchange membranes were prepared. • Effect of the content of methylhydroquinone on AEMs' properties was studied. • The AEMs showed low swelling ratio, excellent mechanical properties. [ABSTRACT FROM AUTHOR]

In this paper, poly(ether ether ketone) (PEEK) scaffold was manufactured using the fused deposition modeling (FDM) technology with a modified platform. The effect of processing parameters of FDM on the porosity and compressive strength of PEEK scaffold with uniform pores (0.8 mm of diameter) was optimized through Taguchi methodology. With the determined parameters, four kinds of PEEK scaffolds with gradient pores (0.4–0.8 mm, 0.6–1.0 mm, 0.8–1.2 mm, and 1.2–2.0 mm) were manufactured. The scaffolds were investigated using scanning electron microscopy. The results showed that the pores of scaffolds were interconnected with rough surface, which can allow the attachment, migration, and differentiation of cells for bone forming. The tensile strength, compressive max strength, and compressive yield strength of scaffolds were between 18 and 35 MPa, 197.83 and 370.42 MPa, and 26 and 36 MPa, respectively. The mechanical properties of the scaffolds can satisfy the loading requirements of human bones. Therefore, the PEEK scaffolds have a potential to be used in tissue engineering as implants. [ABSTRACT FROM AUTHOR]

Poly(ether ether ketone) (PEEK) is a high-performance thermoplastics with outstanding mechanical properties and thermal resistance (serving temperature up to 250 °C). Although many studies have been performed on the stress–strain behavior and related modeling, less attention has been paid on the structural and orientational evolution of PEEK during tensile deformation. In this work, the orientational and structural evolution during tensile deformation at a wide range of temperatures from 30 to 170 °C was probed ex situ by wide-angle X-ray diffraction and differential scanning calorimetry. The enthalpy of cold crystallization of PEEK as a function of strain, which reflects the content of amorphous fraction and the disorder degree of crystals, presents an interesting dependence on tensile temperature. The evolution of orientation with strain is strongly dependent on the tensile temperature. Oriented PEEK presents much improved modulus and tensile strength compared to that of undrawn PEEK. This finding demonstrated that pre-stretching especially at temperatures above Tg is an effective way to improve the mechanical property of PEEK. [ABSTRACT FROM AUTHOR]

Poly(ether ether ketone) (PEEK) was irradiated with 4 MeV O+ and 5 and 10 MeV Au+ ions to the fluences from 1012 to 1014 cm−2 and then treated in 5 M/l water solution of LiCl for one month at room temperature. After drying and removal of LiCl surface contamination, the depth distribution of LiCl embeded in PEEK was measured by the neutron depth profilig method (NDP) sensitive to 6Li isotope. Embeded LiCl is believed to map distribution of water diffusing into PEEK interior. The results show that the PEEK irradiated to the fluences above 1.1013cm−2 is prone to water penetration to the depths of few microns. On the pristine PEEK and that irradiated to lower ion fluences only a surface Li contamination is observed. [ABSTRACT FROM AUTHOR]

Sulfonated poly(ether ether ketone) (sPEEK) membrane is a promising proton-conducting membrane for fuel cell. However, the performance and lifetime of sPEEK membrane depend on the degree of sulfonation (DS). High DS of sPEEK increases the performance, but the mechanical properties could deteriorate progressively which affect its lifetime. Thus, this study investigated the effect of adding polyvinylidene fluoride (PVDF) into high DS (80%) of sPEEK through solution blending method toward its physicochemical properties and morphology structures. The PVDF concentration was varied to 5, 10, 15, and 20 wt% relative to the sPEEK content. The existence of hydrophobic PVDF in 80% sPEEK improved the mechanical properties where the water uptake and swelling degree of membrane decreased, whereas the tensile strength increased. The sPEEK/PVDF 15 exhibited the highest proton conductivity (46.23 mS cm−1) at 80°C. Incorporating PVDF into high DS of sPEEK enhanced the mechanical properties which can be used as a proton-conducting membrane for fuel cell that may improve the performance and prolong the lifetime of the cell. [ABSTRACT FROM AUTHOR]

High-performance anion exchange membranes (AEMs) are in need for practical application of AEM fuel cells. Novel branched poly(ether ether ketone) (BPEEK) based AEMs were prepared by the copolymerization of phloroglucinol, methylhydroquinone and 4,4′-difluorobenzophenone and following functionalization. The effects of the branched polymer structures and functional groups on the membrane's properties were investigated. The swelling ratios of all the membranes were kept below 15% at room temperature and had good dimensional stability at elevated temperatures. The branching degree has almost no effect on the dimensional change, but plays a great role in tuning the nanophase separation structure. The cyclic ammonium functionalized membrane showed a lower conductivity but a much better stability than imidazolium one. The BPEEK-3-Pip-53 membrane with the branching degree of 3% and piperidine functionalization degree of 53% showed the best performances. The ionic conductivity was 43 mS cm−1 at 60 °C. The ionic conductivity in 1 M KOH at 60 °C after 336 h was 75% of its initial value (25% loss of conductivity), and the IEC was 83% of its initial value (17% loss of IEC), suggesting good alkaline stability. The peak energy density (60 °C) of the single H 2 /O 2 fuel cell with BPEEK-3-Pip-53 membrane reached 133 mW cm−2 at 260 mA cm−2. • A novel branched poly(ether ether ketone) based AEM was prepared. • The branched AEMs showed high conductivity and low swelling ratio. • A high peak power density was achieved for single cell with the branched AEM. [ABSTRACT FROM AUTHOR]

• Both GNP and C 60 enhanced the modulus of PEEK significantly. • The reinforcing effect of C 60 on PEEK was more pronounced compared to GNP. • The thermal stability of PEEK was improved by the addition of GNP or C 60. • The tan δ peak height of PEEK decreased with increasing the content of GNP. • The tan δ peak height of PEEK kept constant irrespective of the addition of C 60. Poly(ether ether ketone) (PEEK) is a high-performance engineering plastics, being widely used in aerospace, automobile and biomedical applications. In this work, the effect of fullerenes (C 60) and graphene nanoplatelets (GNP) on the properties of PEEK was compared. It was found that both C 60 and GNP enhanced the modulus of PEEK significantly and the reinforcing effect was more pronounced for C 60. Most interestingly, the tan δ peak height of PEEK kept constant irrespective of the addition of C 60 , while it decreased gradually with increasing the content of GNP. This study suggests that C 60 appears to be the best filler of PEEK if the damping property of the materials is a critical concern. [ABSTRACT FROM AUTHOR]

Poly(ether ether ketone) (PEEK) is an alternative material to metals for orthopedic applications. However, the compatibility of PEEK with hard tissues needs to be improved. To address this issue, this study proposes a novel technique for PEEK surface modifications. A polyphosphodiester macromonomer (PEPMA·Na) was synthesized via the demethylation of polyphosphotriester macromonomer obtained via the ring-opening polymerization of cyclic phosphoesters using 2-hydroxypropyl methacrylamide as the initiator. The surface modification of PEEK was performed via photoinduced and self-initiated graft polymerization of PEPMA·Na without using any photoinitiators. The amount of phosphorus due to poly(PEPMA·Na) immobilized on PEEK increased with an increase in the photoirradiation time. The PEEK surface turned hydrophilic due to poly(PEPMA·Na) grafting, with almost similar advancing and receding contact angles, implying that the modified PEEK surface (PEEK-g-poly(PEPMA·Na)) was homogeneous. Specimens were mineral coated by simple static soaking in ×1.5 simulated body fluid (1.5SBF) and by an alternative process that included additional soaking steps in 200 mM CaCl2 aq. and 200 mM K2HPO4 aq. before static soaking in 1.5SBF. Specimens were immersed in 1.5SBF for 28 days in simple static soaking, after which the PEEK-g-poly(PEPMA·Na) surface was completely covered with spherical cauliflower-like mineral deposits that resembled octacalcium phosphate (OCP). Their structural similarities were confirmed via X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), and X-ray fluorescence (XRF) analyses. However, these mineral deposits were not observed on the bare PEEK surface. Due to the additional soaking steps (alternative soaking) undertaken before the static soaking of the specimens in 1.5SBF, the mineral coating on the PEEK-g-poly(PEPMA·Na) was dramatically accelerated and the surface was fully covered with mineral deposits in only one day of soaking. The mineral deposits resulting from both the soaking processes had similar structures. Compared with bare PEEK, osteoblastic MC3T3-E1 cells proliferated more actively on mineral-coated PEEK-g-poly(PEPMA·Na). Thus, the surface immobilization of poly(PEPMA·Na) on a PEEK surface is effective for mineral coating and may be useful to provide hard-tissue compatibility on PEEK. [ABSTRACT FROM AUTHOR]

Abstract Poly(ether ether ketone) (PEEK), with its superb mechanical properties, excellent chemical resistance and high thermo-oxidative stability is one of the most important engineering thermoplastics for high-end applications. In this work, we investigate the elastic and viscoelastic properties along with the creep mitigation of two sets of samples: PEEK reinforced with graphene nanoplatelets (GNPs) and PEEK reinforced with a hybrid graphene/short carbon fibre (CF) filler. The melt viscosity of the PEEK nanocomposites was found to increase with increasing GNPs content; however, the viscosity of the hybrid CF-GNP samples with the highest filler content was equal to the one of the samples filled only with GNPs at low shear rates. This processability shows the advantage of GNPs over other nano and conventional fillers in the ability to use meaningful loadings. The introduction of GNPs improved significantly the stiffness and the storage modulus of the materials in both PEEK-GNP and PEEK-CF-GNP composites. Moreover, the presence of GNPs within the composites led to a restriction of the mobility of the macromolecular chains of PEEK, which resulted in enhanced creep properties at both room temperature and elevated temperatures. Overall, the nanocomposites produced displayed properties that make them attractive in applications where high stiffness and structural integrity at elevated temperatures are required. [ABSTRACT FROM AUTHOR]

Abstract Side-chain-type quaternized aromatic polyelectrolytes named QBz-PEEK-x have been synthesized via one-step benzylation modification of commercial poly(ether ether ketone) (PEEK). By controlling the molar ratio between the benzylation reagent and PEEK, the substitution degree x could be tuned in a wide range (51.1%~ 91.6%). A series of five anion exchange membranes (AEMs) with high mechanical strength were facilely prepared via solution-casting of QBz-PEEK-x. Water uptake, swelling ratio and ion conductivity of these AEMs were investigated in detail. Of particular interest is that, at 60 °C, the AEM of QBz-PEEK-76.0% exhibited a moderate water uptake of 56%, a low swelling ratio of 15%, and an exceptionally high OH– conductivity of 155 mS cm−1 which was comparable to the top values ever reported. Moreover, a promising peak power density of 391 mW cm−2 was achieved when assembling QBz-PEEK-76.0% AEM in a H 2 /O 2 single cell operated at 70 °C. This unprecedented "benzylation" method opens a new door to novel high performance side-chain-type AEMs. Graphical abstract Unprecedented one-step benzylation modification of commercial poly(ether ether ketone) (PEEK) yielded high performance AEMs. fx1 Highlights • One-step benzylation modification of PEEK yielded soluble polyelectrolytes. • An AEM exhibited an exceptionally high OH– conductivity of 155 mS cm−1 at 60 °C. • A promising peak power density of 391 mW cm−2 was achieved in a H 2 /O 2 single cell. [ABSTRACT FROM AUTHOR]

• Response tolerance to the high dose (500 kGy) irradiation in air and water of highly sulfonated SPEEK is demonstrated. • Thermal and mechanical properties for SPEEK with degree of sulfonation up to 70 % remain stable after high dose irradiation compared to nonirradiated SPEEK membranes. • Irradiation in water enhances reduction of molecular arrangement at the DS > 70 % causing membrane dissolution in water. • Improved molecular arrangement due to the physical interaction of sulfonated groups affects mechanical stiffness of SPEEK60-70 membranes after irradiation in water. Sulfonated poly(ether ether ketones) (SPEEK) have raised interest as a replacement of Nafion® proton exchange membranes (PEM) for the application in harsh environments involving material exposure to ionizing radiation, for example, radioactive hydrogen isotope separation from water. This study is dedicated to evaluate the effects of high dose (500 kGy) electron beam irradiation on the physico-chemical and thermomechanical properties of highly sulfonated (degree of sulfonation 60–90 %) SPEEK membranes irradiated in air and water. Spectrometric and thermogravimetric analysis indicated slight changes in the material properties after irradiation with increase of the degree of sulfonation (DS). Tensile tests and thermomechanical analysis of irradiated samples indicated notable deterioration of properties at higher DS values. Results demonstrate that SPEEK membranes with DS around 70 % could be a replacement of the traditional PEM for the applications where exposure to ionizing radiation occurs. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration membranes have been prepared from poly(ether-ether-ketone) (PEEK) by phase inversion. Remarkably, these membranes undergo negligible ageing, even under extreme conditions of high temperature air annealing, and high temperature solute filtration with aggressive solvents. This negligible ageing of PEEK membranes is contrasted with substantial ageing of crosslinked polybenzimidazole (PBI) and polyimide (PI) membranes. After air annealing at 120 °C, PBI and PI membranes become brittle and lose all permeance, whereas PEEK membranes remain flexible and retain a constant permeance of ~0.2 L h −1 m −2 bar −1 for tetrahydrofuran (THF). The structural change in PBI and PI membranes is attributed to polymer transition from a non-equilibrium glassy state towards an equilibrium state at which chain packing precludes permeation of solvent. High temperature filtrations in DMF up to 140 °C for the three polymeric membranes showed PEEK performance to be stable and consistent with negligible ageing, whereas PBI and PI rapidly loose stability. [ABSTRACT FROM AUTHOR]

Poly(ether ketone ketone) (PEKK) and poly(ether ether ketone) (PEEK) are high-performing thermoplastics applicable for solvent-resistant nanofiltration due to their outstanding resistance to harsh conditions. However, the polymers require strong acids for solubilization and use as dope solution for membrane preparation. This is the major limitation when targeting hollow fibers (HF) since the metallic spinning line and spinnerets could be prone to corrosion in long term. In this work, we propose the fabrication of an acid-resistant spinneret by 3D printing technology through stereolithography using acrylate and methacrylate-based resins. The hollow fibers are produced by interplaying spinneret designs and spinning conditions with an acid-resistant spinning line. The fabricated hollow fibers exhibited N,N -dimethylformamide (DMF) permeance of 1.4–2.7 L m−2 h−2 bar−1, with a molecular weight cut-off around 246 g mol−1 confirmed with more than 90% rejection of 1,3,5-tri- tert -butyl benzene (TTBB). Furthermore, the hollow fiber modules were tested at high-temperature filtration in DMF with confirmed membrane flux or structural dimension stability. [Display omitted] • Fabrication of acid-resistant spinnerets using 3D printing. • Hollow fiber spinning of poly(aryl ether ketone) for nanofiltration. • Solvent-resistant hollow fibers with DMF permeance of 2.7 L m−2 h−2 bar−1. • Hollow fibers with molecular weight cut-off 246 g mol−1 [ABSTRACT FROM AUTHOR]

Nano-porous poly(ether ether ketone) (PEEK) hollow fiber membranes were successfully fabricated from PEEK/polyetherimide (PEI) blends via thermally-induced phase separation (TIPS) followed by chemical extraction of PEI method. The gas permeation rates, morphologies and mechanical properties of membranes were systematically investigated under different spinning conditions. The content of PEEK in blends substantially determined the gas permeation rates following the order: PEEK30/PEI70 (~9000 GPU) > PEEK40/PEI60 (~5100 GPU) > PEEK50/PEI50 (~1700 GPU) > PEEK60/PEI40 (~300 GPU) > PEEK70/PEI30 (below 1.0 GPU). Faster winding rates and bigger N 2 bore fluid flow rates would result in bigger pores, higher porosity and larger gas permeation rates, while would cause lower mechanical strength. Furthermore, the silane-grafted hydrophobic PEEK hollow fiber membranes were successfully prepared via one-step reduction followed by silane modification. The performance of virgin and modified membranes was evaluated by treating saline feed containing 3.5 wt% sodium chloride in vacuum membrane distillation (VMD) process. Compared with virgin PEEK membrane, the modified membranes exhibited a more stable flux and higher salt rejection over 99.9 % for 33 h, indicating the significant improvement in the anti-wetting property caused by silane modification. The application attempt expands the research direction of PEEK membranes and promotes its further application potential in VMD process. [Display omitted] • Nano-porous PEEK hollow fiber membrane was made via TIPS followed by RPR process. • Effects of spinning parameters on PEEK membrane properties were studied. • Hydrophobic PEEK membrane was prepared by one-step reduction and FAS grafting. • The application of FAS-grafted PEEK membrane in VMD was first studied and reported. • FAS-grafted PEEK membrane showed good anti-wetting property and high salt rejection. [ABSTRACT FROM AUTHOR]

• The interior structure of PEEK composites was studied by XCT. • The preparation methods for FSC specimens on filler homogeneity was investigated. • The method of getting reliable data on fiber-filled composites was identified. The feasibility of using FSC for fiber-filled polymer composites is questionable since the typical FSC sample thickness is comparable to the fiber diameter. In this study, X-ray computed tomography (XCT) with an ultra-high-resolution was performed to reconstruct the interior structure of poly(ether ether) ketone (PEEK) composite pellets. Using reconstructed 3D XCT matrices of PEEK resin, glass fibers, and voids, PEEK pellets sliced with different directions and sampling frequencies were analyzed to mimic FSC sample preparation. For the sample thicknesses less than 50 μm, PEEK samples sliced perpendicular to the fiber flow direction had good filler homogeneity and always had a lower coefficient of variation than pellets sliced along the fiber flow direction. This conclusion is later supported by the isothermal crystallization kinetics of PEEK and its composites investigated by differential scanning calorimetry and fast scanning calorimetry over a wide temperature range relevant to processing. [Display omitted] [ABSTRACT FROM AUTHOR]

The effect of nanosilica addition on the ionic conductivity, water uptake, and mechanical properties of poly(styrenesulfonic acid)-grafted poly(ether ether ketone) polymer electrolyte membranes (PEEK-PEMs) were investigated using silica-containing PEEK-PEMs ( PEM-Si1 , -Si3 , and -Si5 ) prepared by radiation-induced graft polymerization to nanosilica (1, 3, and 5 wt%)-dispersed PEEK films ( PEEK-Si1 , -Si3 , and -Si5 ). PEEK-Si3 and -Si5 exhibited 10%–50% higher grafting degrees (GDs) compared with those of a silica-free PEEK film. PEM-Si3 and -Si5 showed similar and slightly higher water uptakes in the lower- and higher-relative-humidity (RH) ranges compared with that of the silica-free PEMs. Under the fully humidified condition at 80 °C, PEM-Si3 exhibited the highest tensile strength (TS) (16.4 MPa), which is 1.27 and 1.64 times greater than those of the silica-free PEM and Nafion 212. The membrane electrode assembly (MEA) prepared from PEM-Si3 with an IEC of 3.30 mmol/g showed a maximum power density of 612 mW/cm 2 under 30% RH, which was 7% higher than that of the silica-free PEM-based MEA. On the basis of the aforementioned results, we concluded that (1) nanosilica was introduced into both hydrophilic (ion channel) and hydrophobic (matrix PEEK) phases in the PEMs; (2) nanosilica in the hydrophilic phase exhibits greater water absorption tendency but not greater water retention character, under high- and low-RH conditions, respectively; and (3) nanosilica in the hydrophobic phase increases the mechanical properties of silica-containing PEMs. [ABSTRACT FROM AUTHOR]

The development of alkaline anion exchange membrane (AEM) with both high ion conductivity and stabilities is of great significance for fuel cell applications. In this study, a facile acid-base blending method is designed to improve AEM performances. Basic imidazolium-functionalized poly (ether ether ketone) with a high functionalization degree is employed as polymer matrix to pursue high ion-exchange capacity (IEC) as well as high hydroxide conductivity, meanwhile acidic sulfonated poly (ether ether ketone) (SPEEK) is employed as the cross-linking agent to enhance the stabilities of the blend membranes. Particularly, an in-situ Menshutkin/crosslinking method is exploited to prevent the flocculation in the preparation process of blend membranes. As a result, dense and defect-free blend membranes are obtained. The blend membranes exhibit high level of IEC up to 3.15 mmol g −1 , and consequently possess elevated hydroxide conductivity up to 31.59 mS cm −1 at 30 °C. In addition, benefiting from the strong electrostatic interaction introduced by the acid-base blending, the stabilities and methanol resistance of blend membranes are enhanced. [ABSTRACT FROM AUTHOR]

Polyaryletherketones (PAEKs) are a class of ultrahigh performance polymers with outstanding temperature and chemical resistance. Poly(ether ketone ketone) copolymer (Kepstan®) and poly(ether ether ketone) (PEEK) display intrinsic insolubility in nearly all organic solvents. The primary issue for the application of these polymers is their processability which requires a high temperature/pressure-based technique, or the use of harsh and corrosive solvents, like methanesulfonic and sulfuric acid, resulting in sulfonation of the polymer backbone that adversely might affect their chemical stability. In this work, we propose a method to prepare porous Kepstan® and PEEK membranes using N -methyl-2-pyrrolidone (NMP) as solvent at room temperature. It consisted of a modification-regeneration strategy to turn commercial semi-crystalline Kepstan® and PEEK into dithiolane soluble derivatives that allow the fabrication of hollow fiber, flat-sheet, and electrospun nanofibers. The resulting membranes are then regenerated to the solvent-resistant materials. The novel Kepstan® and PEEK hollow fibers exhibited a N,N -dimethylformamide (DMF) permeance of 2.21 and 2.05 L m−2 h−2 bar−1, with more than 90% rejection of Crystal Violet (408 g mol−1) and Methyl Orange (327 g mol−1), respectively. [Display omitted] • Porous PEKK and PEEK hollow fiber membranes spun without strong acids at room temperature. • Solvent and temperature-resistant hollow fibers from commercial PEKK and PEEK. • Effective separation of molecules in the range of 327–408 g mol−1 in dimethylformamide. • Chemical modification-regeneration strategy to promote the polyketone processability. [ABSTRACT FROM AUTHOR]

A series of asymmetric membranes based on a trifluoromethylphenylated poly(ether ether ketone) (CF3-PEEK) were prepared using a dry–wet phase inversion method. To obtain the asymmetric membranes with defect-free skin, the type and concentration of internal nonsolvent and the evaporation time were carefully investigated. The cross-section of membranes was characterized by scanning electron microscopy. The gas separation performance of asymmetric membranes was tested in terms of gas permeabilities and selectivities for helium, carbon dioxide (CO2), oxygen (O2), and nitrogen by the constant volume method. It was found that the permeabilities of asymmetric membranes were obviously higher than that of CF3-PEEK dense membrane. The membranes in series 2 showed higher permeability for each gas while the separability for gas pair CO2/O2 increased from 3.78 to about 6 comparing with that of the dense membrane. [ABSTRACT FROM PUBLISHER]

Poly(ether ether ketone) (PEEK)/polytetrafluoroethylene (PTFE) composite coatings with different PTFE contents were successfully fabricated using electrostatic spraying. The crystalline structure of the PEEK/PTFE coatings was characterized by X-ray diffraction analysis. The effects of PTFE addition in the composite coatings on the hardness, adhesion, and tribological performance were discussed. The hardness and adhesion level of PEEK/PTFE coatings were not significantly affected by the addition of PTFE, which indicated that the coating possesses excellent mechanical properties. The PEEK/PTFE coatings showed better tribological performance than traditional PEEK coating. The PTFE/PTFE-3 (3 wt% mass fraction of PTFE in composite coating) coating has a friction coefficient of 0.133 (PEEK is 0.149) and wear rates of 3.8 × 10−5 mm3 N−1 m−1 (PEEK is 4.4 × 10−5 mm3 N−1 m−1). [ABSTRACT FROM PUBLISHER]

Abstract: A series of quaternary phosphonium-functionalized poly(ether ether ketone)s (PEEK-QPOHs) have been synthesized by phosphorization reaction, and their membranes have been prepared by a solution casting method. Ion exchange capacity (IEC) of PEEK-QPOH membranes ranges from 0.89 to 1.19mmolg−1 with the degree of chloromethylation from 70% to 126%. Not only are PEEK-QPOH polymers soluble in typical high-boiling-point membrane-forming solvents, but also they are soluble in some low-boiling-point water-miscible solvents (low alcohols), implying their ability to serve as both membranes and ionomers. PEEK-QPOH membranes showed high hydroxide conductivity, e.g., a PEEK-QPOH 126% membrane (with IEC of 1.19mmolg−1) exhibited 61 and 89mScm−1 at 20°C and 60°C, respectively. Based on the same polymer backbone of PEEK, quaternary phosphonium-functionalized PEEK membranes are more hydroxide-conductive and more alkali-stable than quaternary ammonium- and imidazolium-functionalized counterparts. All these properties indicate PEEK-QPOH is one of the most promising HEM materials for potential applications in alkaline membrane fuel cells. [Copyright &y& Elsevier]

In the present study, the effect of P-EPQ, an organophosphonite antioxidant, on the glass transition and the viscoelastic behavior of optimized poly(ether ether ketone) (PEEK)/poly(ether imide) (PEI; PEEK/PEI: 50/50) blend has been reported. For this, P-EPQ was added in various proportions to the PEEK/PEI blend and was studied by quasi-isothermal modulated differential scanning calorimetry (Qi-MDSC) and dynamic mechanical thermal analysis (DMTA) methods. The Qi-MDSC results clearly indicate a significant decrease in the glass transition temperature of the blend up to 1 wt% P-EPQ addition. The DMTA measurements revealed a decrease in tan δ peak temperature upon antioxidant addition in agreement with calorimetric results. The shift factors obtained using the time–temperature superposition of DMTA data exhibit Williams–Landel–Ferry behavior, and the fractional free volume of the blend increases with increase in antioxidant addition (up to 1 wt%). The “master curve” of storage modulus predicts high modulus for the blend with 1 wt% antioxidant, revealing its suitability for high-impact applications. [ABSTRACT FROM PUBLISHER]

Abstract: In order to mitigate problems associated with highly sulfonated aromatic hydrocarbon membranes, such as dimensional stability, mechanical strength, and methanol crossover, sulfonated poly(ether ether ketone) (SPEEK) membranes containing 1,6-bis(4-vinylphenyl)hexane (BVPH) were crosslinked by EB irradiation. Compared to the pristine SPEEK membrane, the crosslinked membranes exhibited significantly improved dimensional stability, chemical stability, and mechanical strength. The crosslinking procedure slightly reduced the proton conductivity of the membranes. The crosslinking of SPEEK with BVPH was also found to slightly reduce the proton conductivity of the membranes, but significantly reduced the methanol permeability. [Copyright &y& Elsevier]

A series of imidazolium-functionalized poly(ether ether ketone)s (PEEK-ImOHs) were successfully synthesized by a two-step chloromethylation–Menshutkin reaction followed by hydroxide exchange. PEEK-ImOH membranes with ion exchange capacity (IEC) ranging from 1.56 to 2.24 mmol g−1 were prepared by solution casting. PEEK-ImOHs show selective solubility in aqueous solutions of acetone and tetrahydrofuran, but are insoluble in lower alcohols. PEEK-ImOH membranes with IEC of 2.03 mmol g−1 have high hydroxide conductivity (52 mS cm−1 at 20 °C), acceptable water swelling ratio (51% at 60 °C), and great tensile strength (78 MPa), and surprising flexibility (elongation-to-break of 168%), and high thermal stability (Decomposition temperature: 193 °C). In addition, PEEK-ImOH membranes show low methanol permeability (1.3–6.9 × 10−7 cm2 s−1). PEEK-ImOH membrane was tested in methanol/O2 fuel cell as both the HEM and the ionomer impregnated into the catalyst layer; the open circuit voltage is 0.84 V and the peak power density is 31 mW cm−2. [ABSTRACT FROM AUTHOR]

With the rapid advancement of 5G communication technologies, there is an urgent need to develop materials with low dielectric loss for compact and high-efficiency flexible copper clad laminates (FCCL). To address the issue of relatively high dielectric loss of the combination of a polyimide (PI) film and a bonding sheet for 5G FCCL substrate, this study investigated poly(glycidyl methacrylate)-grafted poly(ether ether ketone) (PEEK- g -PGMA), which was prepared via UV-induced self-initiated surface polymerization. The visual appearance and mechanical properties of the PEEK were maintained after the grafting process, and the thin PGMA layer was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. To optimize the processes of PGMA grafting and hot pressing, 90° peel tests were conducted. As a result, the optimized grafting and hot-press conditions were found to be UV irradiation of 4 min, 1.0 M monomer solution, and hot pressing at 180 °C for 60 min. At 28 GHz, the PEEK- g -PGMA exhibited lower dielectric constant and loss than those of the PI films with commercial bonding sheet. The study presents a straightforward approach to prepare the PEEK- g -PGMA films as a potential bonding sheet-free substrate for 5G FCCL. [Display omitted] [ABSTRACT FROM AUTHOR]

In this report, the bromination of poly(ether ether ketone) (PEEK) using the mild reagent N -bromosuccinimide (NBS) is explored to generate controlled random and blocky microstructures. Bromination proceeded quantitatively in both the solution state and semicrystalline gel-state, and degrees of bromination between 25 and 175 mol% were obtained for both random and blocky BrPEEK. Spectroscopic evidence revealed a higher prevalence of unfunctionalized repeat units for blocky BrPEEK than random BrPEEK at similar degrees of functionality. Furthermore, at similar degrees of bromination, blocky BrPEEK exhibited enhanced glass transition temperatures, greater crystallizability, higher melting temperatures, and faster crystallization kinetics than random BrPEEK, suggesting longer segments of unfunctionalized PEEK in blocky BrPEEK. Overall, this work demonstrates that PEEK can be brominated to very high degrees of substitution in the semicrystalline gel-state while preserving crystallizability and effectively blocking up the functionality. [Display omitted] • Quantitative bromination of PEEK was achieved. • Gel-state chemistry provided blocky microstructural control. • Microstructural control provided tunability of thermal properties. • Blocky microstructures enhanced material properties more than random. • Comparisons to Flory's theory of melting point depression in copolymers performed. [ABSTRACT FROM AUTHOR]

In this study, poly(ether ether ketone) (PEEK)/gadolinium oxide (Gd2O3) composites were prepared by melt extrusion in combination with a Haake rheometer. Differential scanning calorimetry was used to investigate the crystallization behavior of PEEK and its corresponding composites. The microstructural features of the composites and the interfacial interactions between the filler and PEEK phases were viewed with a scanning electron microscope. Gd2O3 powder was blended with PEEK, and sulfonated poly(ether ether ketone) (SPEEK) was used as the compatibilizer in the PEEK/Gd2O3 composites. Isothermal crystallization exotherms showed that the addition of SPEEK increased the crystallization of PEEK in PEEK/Gd2O3 composites. However, the PEEK crystallization rates decreased with increasing Gd2O3 fractions, which probably resulted from the Gd2O3 that had no heterogeneous nucleation effects on the matrix. The modified Avrami equation and Mo’s equation were used to study the nonisothermal crystallization kinetics. The addition of Gd2O3 did not change the nucleation process of PEEK, but it markedly decreased the crystal growth rate. [ABSTRACT FROM PUBLISHER]

Abstract: The effect of crystal morphology, such as the crystallinity and lamellar structure, on the radiation-induced graft polymerization of styrenesulfonate ethyl ester (E4S) onto poly(ether ether ketone) PEEK films was evaluated. The PEEK films possessing crystallinities ranging from 11 to 32% were irradiated with 30–150 kGy, and the graft polymerization was performed in an E4S/1,4-dioxane solution at 80 °C. For the PEEK films with crystallinities between 11 and 26%, the graft polymerization proceeded and reached grafting degrees of up to 70%, whereas for those having crystallinities higher than 26%, the reaction barely proceeded. The concentration of phenoxy radicals that initiated the graft polymerization in the irradiated PEEK films was constant over the entire range of crystallinity (11–32%). On the other hand, in the small-angle X-ray scattering (SAXS) profiles, a discontinuous change in the peak intensity at Q = 0.44 nm−1, which corresponds to a lamellar spacing of 14 nm, was observed at a crystallinity of approximately 26%; namely, the PEEK films with a crystallinities greater than 26% exhibited prominent anisotropic scattering in the drawing direction. Judging from the above results, it can be concluded that the graft polymerization of styrene derivatives onto the PEEK films was affected by the formation of oriented lamellar structures that inhibited monomer diffusion into the films. [Copyright &y& Elsevier]