[en] Structure of nano amorphous matter has not been studied sufficiently yet due to the difficulty in both operation of nano matter and characterization of their structure. In this work, a detailed study of the structural orientation within amorphous polymeric nanofiber and its mechanical strength was conducted for a highly thermal resistant amorphous polymer: poly(phthalazinone ether ketone) (PPEK). Poly(butylene terephthalate) (PBT), a semi-crystalline polymer with partial difference in chain flexibility and geometry to PPEK, was chosen for a comparative discussion. For the method, highly aligned PPEK and PBT nanofiber bundles were prepared by electrospinning with a home-made book-like collecting device. X-ray experiments were conducted to research their structural orientation, and tension experiments were conducted to research their mechanical properties. It was found that the amorphous PPEK nanofibers showed relatively low orientation degree of polymer chain limited by its rigid and twisted segments within the polymer chain, while PBT nanofibers showed not only highly ordered crystal structure but also very large shish length, beneficial from the co-existence of rigid and flexible segments. The above structural information was well supported by their uniaxial tensile behaviors, where PBT nanofiber manifested much larger ultimate stress σ, failure strain ε, Young’s modulus E and toughness than those of PPEK nanofibers and commercial PBT plastic. However, the electrospun PBT nanofibers’ orientation degree, within the range of 0.45–0.7, is much lower than that of some reported melt-spun PBT fibers with the orientation degree above 0.9. Therefore, it can be concluded that the instinct characterization of polymer chain and processing technique have a much more significant influence than size effect on the structural orientation and mechanical strength of nanofibers rather than size effect.

[en] Charge transfer multiplayer films have been prepared by layer-by-layer self-assembly technique. The films incorporate the rare-earth-containing polyoxometalate K₁₁[Eu{PW₁₁O₃₉}₂].nH₂O and the rich electron polyelectrolyte poly(3-viny-1-methyl-pyridine) quaternary ammonium and display a linear increase in the absorption and film thickness with the number of deposition cycles. Ultraviolet and visible absorption spectra, atomic force micrographs, small-angle X-ray reflectivity measurements, and photoluminescence spectra were used to determine the structure of films. Linear and regular multilayer growth was observed. We can observe the formation of charge transfer complex compound in multiplayer by layer-by-layer assembly method. Most importantly, the luminescence spectra show the charge transfer band in assembly films, which suggest that energy could be effectively transferred to rare earth ions in assembly multiplayer films

[en] Highlights: • Polymer-based oxidation-resistance coatings were prepared on C/C composites. • Effect of inorganic fillers on oxidation behaviour of polymer coatings is studied. • Coatings were fabricated by simple preparation technique and low temperature curing. • The polymer-based coatings can be applied to large-scale structures. • The good oxidation resistance is due to the formation of borosilicate glasses. -- Abstract: A novel oxidation resistant thermoset polymer (MSCB) with excellent thermo-oxidative stability and good solubility was designed and synthesized. To prevent C/C composites from oxidation, a series of MSCB polymer-based coatings were prepared by precursor infiltration and thermal-curing at 300 ℃. The oxidation behaviour of the MSCB-, MSCB/TiO₂-, MSCB/ZrO₂- and MSCB/SiC-coated C/C composites was studied. The improved oxidation resistance of the C/C composites was attributed to the good adhesion of the coatings and the formation of a borosilicate protective layer on the surface of the coatings, which was confirmed by the results of TGA, SEM, XPS, and XRD analyses.

[en] Chloromethylated poly (phthalazione ether sulfone) (CMPPES) material was prepared with chloromethyl ether as chloromethylating regent and sulfuric acid as solvent. The effect of chloromethyl ether quantity on the chlorinity degree of chloromethylation (DCM) of CMPPES was investigated. DCM of CMPPES was in the range of 1.94-2.89 mmol/g. CMPPES were identified with ¹H NMR and TGA. Compared with PPES, the thermal stability of CMPPES decreases obviously. The CMPPES was dissolved in NMP (10 wt%) and cast on glass to form a membrane. The final anion exchange membranes were prepared by soaking CMPPES in trimethylatine (33%) to aminate. Ion-exchange capacity (IEC), water content, dimensional stability and membrane area resistance of the anion exchange membranes were investigated. It was found that IEC of final anion exchange membrane was between 1.38 and 2.12 mmol/g, and water content of anion exchange membrane increased with an increase of IEC, however, dimensional stability and area resistance of membranes for 2 M VOSO₄ in 3 M H₂SO₄ solution decreased. The area resistance was lower than Nafion112

[en] In this study, we describe a novel strategy to design and construct POSS-modified silane layer on carbon fiber (CF) to strengthen the interfacial adhesion and anti-hydrothermal aging behaviors of CF-reinforced copoly(phthalazinone ether sulfone)s (PPBES). POSS was first modified by 3-aminopropyltriethoxysilane (APS) to improve chemical reactivity. Without separation and purification, APS-c-POSS was used to functionalize CF to improve reactivity and ensure the covalent linkages between CF and POSS-modified silane layer. CF coated with POSS-modified silane layer was obtained by in situ hydrolysis of APS-c-POSS. FTIR and XPS confirmed the chemical bonds between CF and POSS-modified silane layer. Dynamic contact angle, dynamic wetting test and AFM tests demonstrated that POSS-modified silane coating can increase the wettability and roughness, which could improve interlaminar shear strength and flexural strength of CF/PPBES composites by 17.5 and 30.0% with slight enhancement on tensile strength of CF. The failure mechanisms of CF/PPBES composites with and without POSS-modified silane layer were both investigated by SEM in detail. Moreover, this layer was helpful to dynamic mechanical property and hydrothermal resistance of CF/PPBES composites. This study provides alternate strategy to modify CF with POSS, which will significantly broaden the application field of POSS in advanced composites.

[en] Highlights: • The 1D heteroatoms-doped Fe₃C@C absorber is prepared using a facile method. • Chemical states of nitrogen atoms are influenced by thermal treatment process. • The maximum EAB reaches 4.9 GHz with the thickness of 1.6 mm. • Excellent MA ability is achieved due to synergistic effect of multiple mechanisms. -- Abstract: Emergency situation of electromagnetic microwave pollution generated by daily electronic devices urgently requires light-weight and efficient microwave absorption materials with thin thickness and low filling ratio. Herein, the heteroatoms-doped Fe₃C@C nanofibers are fabricated from a mixture solution of Iron (III) 2, 4-pentanedionate (Fe(acac)₃) and nitrogen-containing polymer poly (phthalazinone ether nitrile ketone) (PPENK) by electrospinning and the following thermal treatment. The morphologies and compositions of nanofibers can be controlled by annealing temperature. The 1-Dimensional (1D) heteroatoms-doped Fe₃C@C nanofibers display outstanding microwave absorption performance. When the filling ratio is 30 wt% in paraffin for nanofibers heat-treated in 700 ℃, the optimal reflection loss value is − 35.5 dB at 8.3 GHz with a thickness of 2.8 mm. Additionally, the maximal efficient absorption bandwidth reaches as wide as 4.9 GHz ranging from 13.1 to 18.0 GHz with a rather thin thickness of 1.6 mm. The Fe₃C@C nanofibers have adjustable electromagnetic parameters and thus, balance impedance matching and microwave attenuation performance at the same time. This work investigates the relationship between microwave absorption performance and the chemical states of nitrogen atoms, revealing a facile strategy to prepare a multi-interface microwave absorber and presenting a candidate application for microwave absorption materials with low matching thickness.

[en] Highlights: •Polymer-based oxidation-resistance coatings were prepared. •The mechanism of oxidation resistance was investigated. •Polymer-derived ceramic coating was prepared. -- Abstract: To improve the oxidation resistance of carbon fibers, a series of carborane-containing polymer-based coatings were prepared. The oxidation resistance and microstructure of the coatings were investigated. According to XPS, FT-IR and XRD analysis, the high oxidation resistance of the polymer-based coatings was attributed to the boron oxide protective layer formed from the oxidation of carborane groups in the coating. Ceramic coatings were prepared from heat treatment of polymer-based coatings under argon at 1300 °C for 2 h. The great oxidation resistance of the ceramic coating was attributed to the existence of boron carbide in coating.

[en] Single-layer and double-layer polyurethane (PU) matrix coatings containing spherical carbonyl iron (SCI) and flaky carbonyl iron (FCI) were designed and prepared by using a simple and effective manufacturing method, and the thickness of the coatings was kept at 1.5 mm. The complex permittivity, complex permeability and absorption properties of the coatings were investigated in the frequency range of 2–18 GHz. The results indicate that all the single-layer and double-layer coatings exhibit excellent absorption properties and wide absorption bands. By optimizing the filler radio and coating structure, the optimal reflection loss (RL) value can reach − 35 dB at 8.6 GHz and make the widest absorption band reach 15.5 GHz (2.5–18.0 GHz) and 4.9 GHz (10.7–15.6 GHz) for RL < − 5 dB and RL < − 10 dB, respectively. The coatings of SCI/FCI/PU exhibit a broad effective absorption bandwidth, which can be effectively applied to radar signature reduction and electromagnetic interference suppression in military and civil fields.

[en] Highlights: • poly(phenylene-carborane) grafted graphene oxide was designed and synthesized for the first time. • Tunable effective absorption bandwidth was achieved over 2.8–18 GHz. • The absorption bandwidth (RL • GO-PPB shows improved microwave absorption properties compared to GO. • The GO-PPB composite can be used as lightweight and high-efficient microwave absorbers. -- Abstract: The poly(phenylene-carborane) (PPB) is covalently attached to the surface of graphene oxide (GO) for the first time via Ni(0)-catalyzed polymerization, and the functionalization of the GO has been confirmed by XPS, XRD, FT-IR, SEM, TEM and Raman. After grafting of PPB onto GO, the GO-PPB composites exhibit excellent electromagnetic wave absorption properties, which are mainly originated from suitable impedance characteristics, the efficient complementarities of polarization and conductivity between PPB polymers and GO sheets, and the dipole polarization in the defects, functional groups and carborane structures. The effective absorption bandwidth (reflection loss below −10 dB) of GO-PPB composites with a low filler loading (20 wt%) can reach up to 3.6 GHz with a thickness of only 1.1 mm, and the minimum reflection loss of - − 28.3 dB is obtained in 4.2 GHz at the thickness of 3.7 mm.

[en] A new series of six-member sulfonated copolyimides (SPIs) were prepared by one-step solution copolycondensation from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 1,2-dihydro-2-(4-amino-2-sulfophenyl)-4- [4-(4-amino-2-sulfonphenoxy)-phenyl] (2H)phthalazin-1-one (S-DHPZDA), 4,4'-bis(4-aminophenoxy) biphenyl (BAPB) and 1,2-dihydro-2-(4-aminophenyl)-4-[4-(4-(aminophenoxyl)phenyl)] (2H)phthalazin-1-one (DHPZDA). The sulfonation degree (DS) of the SPIs was controlled by the mol ratio of the sulfonated diamine and non-sulfonated diamine. The obtained SPI membranes had excellent thermal stability, high mechanical property and proton conductivity as well as low methanol permeability. The tensile strength of the SPI membranes was ranging from 54.7 to 98.1 MPa, which was much higher than that of Nafion. The SPI membranes exhibited high proton conductivity (σ) and low methanol permeability ranged from 10^-3 to 10^-2 S/cm and 10^-8 to 10^-7 cm²/s depending on the DS of the polymers, respectively.