Biocompatible polyetheretherketone (PEEK) is a favorable material for hard tissue repair due to its similar elastic modulus to that of the human bone. In this work, graphene oxide (GO) reinforced PEEK nanocomposites with different GO loading have been prepared by injection molding. Mechanical testing reveals that the toughness of the reinforced composite varies with the GO loading, with 0.5% GO giving the greatest elongation at break (86.32% greater than pristine PEEK). The underlying toughening mechanism has been attributed to the well-dispersed GO forming π-π* conjugations at the GO / PEEK interface. These conjugations also acted as the nucleation sites for oriented crystallized region in PEEK. As the GO content increases further (e.g > 0.5%), the fillers tend to agglomerate and would disturb the crystallites of PEEK and serve as stress concentration sites, resulting in decreased toughness. The biocompatibility of the composites has been evaluated in vitro, and the results showed that the addition of GO into PEEK favors the adhesion and spreading of bone marrow stromal stem cells, demonstrating the strong potential of our GO reinforced PEEK composites in applications such as hard tissue repair and replacement.

Silicon (Si) anodes display high specific capacity but mostly suffer from poor cycling ability owing to their dramatic volume expansion during the discharge/charge process. An effort was devoted to developing new polymeric binders that could effectively mitigate the capacity fading of Si anodes. Herein, aqueous binders of chitosan-g-poly(acrylic acid) copolymer (CS−PAA) and its sodium salt (CS−PAANa) have been synthesized and applied as the functional binders for the stabilization of Si anodes in lithiumion batteries. The structure and properties of Si anodes based on CS−PAA and CS−PAANa were comparatively characterized by using poly(vinylidene fluoride), chitosan, and poly(acrylic acid) as reference binders. Unlike conventional 1D structural binders, the CS−PAA and CS−PAANa form a cross-linked (3D) network during curing, which maintains mechanical integrity to mitigate Si nanoparticle pulverization effectively. Moreover, the abundant polar groups including carboxylic acid (−COOH) and carboxylate (−COO − ) in the two binders could react with both Si nanoparticles and copper (Cu) current collector to offer robust adhesion, significantly improving electrode integrity after the repeated delithiation/lithiation cycles. Benefitting from the structural advantages, the Si/CS−PAA and Si/CS−PAANa electrodes deliver stable cycling performances of 1243 and 1608 mA h/g at 420 mA/g after 100 cycles.

Developing high-capacity anode materials is urgent for next-generation lithium-ion batteries (LIBs) with the increasing need of larger scale applications. In order to obtain suitable anode materials, nitrogen-doped porous carbon microspheres (NPCMs) were prepared via spray drying followed by carbonization using chitosan as both carbon and nitrogen sources. The structure and properties of NPCMs were characterized by thermogravimetric, Raman spectroscopic, x-ray diffraction, scanning electron microscopic, transmission electron microscopic as well as x-ray photoelectron spectroscopic analysis, and the electrochemical performance of NPCM electrodes were also evaluated. The results show that the diameter of the obtained microspheres is 1–7 μm. When used as the anode material, the NPCMs display a reversible capacity of 443 mAh g−1 at 100 mA g−1 after 120 cycles and maintain a high capacity of 377 mAh g−1 at 1 A g−1 after 500 cycles. Even at a high current density of 4 A g−1, a discharge capacity of 256 mAh g−1 can also be obtained. The excellent rate performance and long cycle life of the electrode might be ascribed to the nitrogen-doping, porous and amorphous structure of NPCMs. The results suggest that the prepared NPCMs have the potential to be used as a promising anode material for high-capacity LIBs.

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High-performance anti-wear polyetheretherketone/polytetrafluoroethylene (PEEK/PTFE) blends have drawn much attention over the past few years, owing to their wide range of potential applications. However, a convenient and effective method to prepare such blends with superior mechanical and tribological properties is still lacking. In this work, we propose a promising approach that uses melt-processable PTFE (MP PTFE), instead of conventional PTFE, to prepare anti-wear blends. MP PTFE, with melt flow abilities under appropriate conditions, can disperse homogeneously in PEEK, enhancing both the mechanical and tribological properties of the PEEK/PTFE blend. To prove this postulation, in this work, both MP PTFE and commercial PTFE were blended with PEEK, separately, and the effects of PTFE type and content on the tensile and tribological properties of the blends were studied. The results showed that, although the addition of commercial PTFE to PEEK could increase the wear resistance, it decreased the tensile strength of PEEK significantly. Compared to the blends with commercial PTFE, the blends with MP PTFE exhibited better tribological performance and higher tensile strength for PTFE content below 10 wt%. It was confirmed that the better dispersion of MP PTFE in PEEK endowed the blends with higher tensile strength. The surface analysis indicated that the MP PTFE could readily migrate to and enrich the surfaces of the blends. The relatively high PTFE content on the surface favored the formation of tribo-films, enhancing the tribological properties of the blends.