In situ growth of CoNi bimetallic alloys inside polyetheretherketone-derived hierarchical porous carbon as a broadband and efficient electromagnetic wave absorber.

Both morphological structure and chemical composition are the important factors that determine the electromagnetic wave (EMW) absorption properties of EMW absorbers. Herein, hierarchical porous carbon (HPPC) was synthesized by using polyetheretherketone (PEEK) as the starting material via the salt template method combined with KOH activation. Then, taking advantage of the hierarchical porous characteristics of the carbon, a novel EMW absorber (HPPC/CoNi) was synthesized by in situ growth of CoNi bimetallic alloys inside the above porous carbon. The as-synthesized HPPC/CoNi exhibits excellent EMW absorption performance with a minimum reflection loss (RLmin) value of -65.56 dB at 2.00 mm and a maximum effective absorption bandwidth (EAB) of 5.92 GHz at 1.80 mm. The superior EMW absorption property is ascribable to the multiple reflection/scattering induced by the hierarchical porous structure of HPPC, dielectric loss, magnetic loss, and good impedance matching. The results show that HPPC/CoNi is a potential EMW absorber with characteristics of ultra-light weight, ultrathin thickness, broad bandwidth, and strong absorption.

Application of Porous Polyetheretherketone Scaffold/Vancomycin-Loaded Thermosensitive Hydrogel Composites for Antibacterial Therapy in Bone Repair.

Polyetheretherketone (PEEK) has been widely used in bone repair, but it often fails due to bacterial infection. Herein, a high-strength porous polyetheretherketone scaffold (ps-PK) loaded with antibacterial drug-loaded hydrogel strategy is proposed. The prepared ps-PK possesses high porosity (30.8-64.7%) and the compression modulus is between 0.4 and 0.98 GPa. The interconnected pore-type structure endows it with a drug loading capacity. Poly(D,L -lactic acid-co-glycolic acid)-b-Poly(ethylene glycol)-b-Poly(D,L -lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) thermoresponsive hydrogels loaded with vancomycin are used as the drug sustained-release system. The vancomycin-loaded hydrogels in the solution state at a low temperature are filled into a porous polyetheretherketone scaffold (ps-PK-VGel) and formed a gel state after implantation in vivo. The antibacterial rate of ps-PK-VGel against methicillin-resistant staphylococcus aureus in vitro is 99.7% and histological observation in vivo demonstrates that the ps-PK-VGel shows obvious antibacterial activity. Given its excellent antibacterial ability and mechanical properties, the porous PEEK scaffold composite drug-loaded thermosensitive hydrogel has great potential in bone repair surgery applications.

Porous carbon/graphite nanosheet/ferromagnetic nanoparticle composite absorbents with adjustable electromagnetic properties.

With the rapid development of electronic devices and wireless communication tools, it is urgent to design and fabricate low-cost, lightweight and effective electromagnetic absorption materials to solve interference of electromagnetic waves. Herein, a new strategy toward porous carbon/graphite nanosheet/ferromagnetic nanoparticle (PC/GNS/Fe) composites was designed to investigate the influence of crystalline carbon on electromagnetic wave absorption. To begin with, graphite nanosheets (GNSs) were incorporated into the porous polyimide by in situ polymerization, and Fe were added as a magnetic particle source and an agent to regulate the pore size. A series of PC/GNS/Fe composite absorbents were obtained. The direct carbonization of porous polymer precursors was beneficial to the design of the pore structure of materials. A hierarchically porous structure derived from the phase separation process was well maintained in the polyimide pyrolysis process. The results demonstrated that the presence of crystalline carbon could influence the reflection loss value and the frequency range. Hence, the absorbing performance can be optimized by adjusting the pore structure and the content of crystalline carbon in materials, which is conducive to obtaining electromagnetic wave absorption materials with excellent comprehensive performance.

Materials with low dielectric constant and loss and good thermal properties prepared by introducing perfluorononenyl pendant groups onto poly(ether ether ketone).

A new monomer, 2,6-difluorophenyl-(4'-perfluorononenyloxy)phenyl-methanone (2F-PFN), was synthesized using a simple two-step reaction. A series of novel poly(ether ether ketone)s (PEEK-PFN-x) containing perfluorononenyl groups were then prepared from 2F-PFN, resorcin, and 4,4'-difluorobenzophenone by nucleophilic polycondensation. The resulting copolymers were found to have different electric and thermal properties depending on the molar ratio of perfluorononenyl groups. PEEK containing a 5% molar ratio of perfluorononenyl (PEEK-PFN-5) possessed an intrinsic low dielectric constant of 2.73 and low dielectric loss of 3.00 × 10-3 at 10 kHz. Another blended polymer prepared from PEEK and PTFE (PEEK/PTFE-5) possessed a dielectric constant of 3.21 and dielectric loss of 6.00 × 10-3 at 10 kHz. Therefore, PEEK/PTFE-5 had much higher dielectric loss than that of PEEK-PFN-5 with the same fluorine content. PEEK-PFN-5 also showed excellent thermal stability, with a 5 wt%-loss temperature of 436 °C. PEEK-PFN-5 showed a slight increase in hydrophobicity, with a water droplet contact angle of 89.7° compared with that of PEEK/PTFE-5 (86.4°) containing the same fluorine content as PEEK-PFN-5. Morphologies and fluoride distribution on the membrane surfaces were characterized by field emission SEM equipped with EDX. These results indicated that PEEK-PFN-5 possessed a more uniform distribution of fluorine on the membrane top surface than PEEK-PTFE-5.

Correction: Materials with low dielectric constant and loss and good thermal properties prepared by introducing perfluorononenyl pendant groups onto poly(ether ether ketone).

[This corrects the article DOI: 10.1039/C7RA13600E.].

A wormhole-like porous carbon/magnetic particles composite as an efficient broadband electromagnetic wave absorber.

A method combining liquid-liquid phase separation and the pyrolysis process has been developed to fabricate the wormhole-like porous carbon/magnetic nanoparticles composite with a pore size of about 80 nm (WPC/MNPs-80). In this work, the porous structure was designed to enhance interaction between the electromagnetic (EM) wave and the absorber, while the magnetic nanoparticles were used to bring about magnetic loss ability. The structure, morphology, porosity and magnetic properties of WPC/MNPs-80 were investigated in detail. To evaluate its EM wave attenuation performance, the EM parameters of the absorber and wax composite were measured at 2-18 GHz. WPC/MNPs-80 has an excellent EM wave absorbency with a wide absorption band at a relatively low loading and thin absorber thickness. At the absorber thickness of 1.5 and 2.0 mm, minimum RL values of -29.2 and -47.9 dB were achieved with the RL below -10 dB in 12.8-18 and 9.2-13.3 GHz, respectively. The Co and Fe nanoparticles derived from the chemical reduction of Co0.2Fe2.8O4 can enhance the graphitization process of carbon and thus improve dielectric loss ability. Polarizations in the nanocomposite absorber also play an important role in EM wave absorption. Thus, EM waves can be effectively attenuated by dielectric loss and magnetic loss through multiple reflections and absorption in the porous structure. WPC/MNPs-80 could be an excellent absorber for EM wave attenuation; and the design strategy could be extended as a general method to synthesize other high-performance absorbers.

New promising hybrid materials for electromagnetic interference shielding with improved stability and mechanical properties.

A novel transparent Co0.2Fe2.8O4@SiO2-polyetheretherketone hybrid material is prepared for electromagnetic interference shielding via in situ sol-gel process. 20% amino-functionalized polyetheretherketone (AFPEEK), containing trifluoromethyl units with excellent solubility is designed and synthesized to improve the stability and mechanical properties of Co0.2Fe2.8O4@SiO2 nanoparticles. The hydrophilic nanoparticles and hydrophobic polymer matrix are covalently connected after the effective interface modification with 3-isocyanatopropyltriethoxysilane. SEM and TEM images demonstrate that the strong interaction between inorganic-organic phases results in great improvement of dispersion and compatibility at even 40 wt% nanoparticles contents. The functional integration of organic polymer and inorganic nanoparticles leads to excellent comprehensive performances such as high transparency, thermal stability and mechanical properties of the hybrid material, as well as the high adhesion with substrate, which benefits its application as coating materials. This high performance material exhibits good superparamagnetic behaviour and microwave electromagnetic properties (RLmax ∼ -13 dB), which can be utilized as a promising electromagnetic interference shielding material.

Poly[bis-(µ(4)-acetato-κO:O:O':O')bis-(µ(3)-acetato-κO:O:O)(µ(2)-acetato-κO:O')(µ(2)-acetic acid-κO:O')di-µ-aqua-copper(II)tris-odium].

In the title compound, [CuNa(3)(CH(3)CO(2))(5)(CH(3)COOH)(H(2)O)(2)](n), the Cu(II) atom lies on an inversion center and is coordinated by four O atoms from four acetate ligands, leading to a square-planar geometry. One Na(I) atom, lying on an inversion center, is coordinated by four O atoms from four acetate ligands and two bridging water mol-ecules in a distorted octa-hedral geometry. The other Na(I) atom is coordinated by five O atoms from five acetate ligands and a bridging water mol-ecule. A hy-droxy H atom lies on a twofold rotation axis and is shared by two acetate ligands. The crystal packing exhibits a polymeric layer parallel to (100), which is further stablized by intra-layer O-H⋯O hydrogen bonds. The layers are linked by inter-layer O-H⋯O hydrogen bonds.

1-Dec-yloxy-4-nitro-benzene.

The title compound, C(16)H(25)NO(3), has a zigzag dec-yloxy chain para to the nitro group of the aromatic ring. There are two independent mol-ecules; the two rings are aligned at 48.15 (7)°. In the crystal, weak C-H⋯O hydrogen bonds lead to the formation of infinite chains.

1-Dodec-yloxy-4-nitro-benzene.

The asymmetric unit of the title compound, C(18)H(29)NO(3), contains two independent mol-ecules. The benzene ring and the mean plane of the alkyl unit form dihedral angles of 83.69 (12) and 77.14 (11)° in the two mol-ecules. In the crystal structure, weak C-H⋯O hydrogen bonds link mol-ecules into double-layer ribbons extending in [110].