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A series of novel cross-linkable PSF-6AF/DBA copolymers with different structure were successfully synthesized via nucleophilic aromatic substitution stepwise polymerization of 4,4′-dichlorodiphenyl sulfone (DCS) with hexafluorobisphenol A (6AF) and 4,4′-(propane-2,2-diyl)bis(2-allylphenol) (DBA) monomer. The 6AF and DBA moieties with a large number of pendant groups had been successfully introduced into the PSF polymer chain. Then, the PSF-6AF/DBA films were fabricated by casting the PSF-6AF/DBA/DMF solutions with the concentration of 10% on the clean glass plates, followed by heat-treating all the films at 300 °C for 4 h. The effects of both the component and cross-linking on the thermal, mechanical and dielectric properties of the obtained films were investigated in detail. Compared to PSF-6AF/DBA films, the cross-linked PSF-6AF/DBA (CS-PSF-6AF/DBA) films show high glass transition temperature (Tg= 184–197 °C) and outstanding mechanical strength (64–77 MPa). More importantly, all CS-PSF-6AF/DBA films display stable dielectric properties in the temperature range of 20–200 °C. The permittivity of CS-PSE-6AF/DBA film at 1 kHz is as low as 2.1, while the dielectric loss is only 0.007.

In this work, the encapsulated barium titanate (BT) (C-PEN@BT) nanoparticles were successfully prepared via rotary coating technology combined with a post-treatment chemical bonding process, by using carboxyl-functionalized poly(arylene ether nitrile) (C-PEN) as modification agent. The TEM, FTIR and TGA results confirmed that the polymer layer (about 8 nm) has been uniformly surrounded on the surface of BT nanoparticles. Then, a facilitated physical dispersion technology was employed to prepare C-PEN@BT filled composite films using crystalline PEN as matrix and 4,4′-bis(3,4-dicyanophenoxy)biphenyl (BPH) as a novel cross-linking agent. The effects of both the surface modification of BT nanoparticles and matrix cross-linking on the mechanical, thermal and dielectric properties of PEN-based composites were investigated in detail. Compared with PEN-I film, the latter results showed that the strong interface interactions exerted between polymer matrix and CPEN layer on BT surface, especially the formation of cross-linking network across the PEN matrix, resulted in increased tensile strength and Young’ modulus by 29% and 32%, respectively. More importantly, the PEN/C-PEN@BT composite film shows stable dielectric properties in the temperature range of 20–204 °C, which is very close to the glass transition temperature.

Composite materials applied to capacitors with high dielectric constant, low dielectric loss and outstanding thermal stability are concerned widely in the field of dielectrics. So committed to the development of dielectric materials with excellent performance is the key factor. In this work, the barium titanate/polyether sulfone (BaTiO3/PES) composite films were prepared by a physical dispersion technology, which utilized a ball milling machine by high-speed circulation, scattered the PES solution contained BaTiO3 in deionized water with the aid of a surfactant. Then, the BaTiO3/PES composite films were obtained through a series of operations, containing reclaimed organic solvent, washed with deionized water, filtered, dried and hot pressed. The morphology of the BaTiO3/PES emulsion was investigated by TEM and SEM. The results showed that the BaTiO3 particles were covered in the PES resin matrix homogeneously. For 50 wt% BaTiO3 reinforced PES composite film. The dielectric constant increased by ~ 227% compared with pure PES resin (4.1 at 1 kHz) and the dielectric loss maintained around 10−2 magnitude, which performed better dielectric properties. The tensile strength of 10 wt% BaTiO3/PES composite films (72 MPa) reached the highest value in comparison with those of pure PES (58 MPa) due to the strengthened interaction between particles and matrix. Further increase of BaTiO3 content, the tensile strength and elongation at break decreased slightly but remained an excellent flexibility from the PES matrix. The temperature at weight loss 5% (T5%) of composite film with 40 wt% of BaTiO3 content reached up to 503 °C in N2 atmosphere. All the BaTiO3/PES composite films performed the concentrated glass transition temperature (Tg) around 229 °C. In sum, excellent thermal stability and dielectric properties would make the BaTiO3/PES composite films become the fine potential candidates for dielectric composites in the capacitors.

Plasmonic heterojunction photocatalysts consisting of silver covered AgBr/BiVO4 structures (Ag@AgBr/BiVO4) were prepared by hydrothermal-photoreduction method. Their phase composition and microstructure were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron and transmission electron microscopies. The photo-generated electron–hole pair recombination rate was characterized by I–t curves and photoluminescence measurements. Visible light absorption range of Ag@AgBr/BiVO4 plasmonic heterojunction was significantly enhanced. Ag@AgBr/BiVO4 showed high efficiency for degradation of rhodamine B (RhB) under wLED light. RhB degraded by ~ 82% during 150 min reaction time. Ag@AgBr/BiVO4 photocatalyst remained constant after 8 cycles indicating its extreme stability. Enhancement mechanism of Ag@AgBr/BiVO4 plasmonic heterojunction photocatalyst is discussed.

To develop high performance of polymer-based composites, the dispersion state and interfacial interaction of nano-fillers are two key issues to be considered. Herein, we report the surface decoration of basalt fibers (BF) with nano-sized barium titanate (BT) particles and their dielectric application in poly(ether sulfone)-based composite laminates (PBCLs) was investigated in detail. Firstly, the nano-sized BT particles uniformly deposited along the BF surface through a simple and effective solvothermal method, as confirmed by SEM and XRD measurement. Then, novel ternary dielectric polymer-based composite laminates, consisting of BT particles decorated BF and poly(ether sulfone) (BT–BF/PES), were fabricated by hot-pressing method. Compared to raw BF filled PBCLs, the SEM images of BT–BF fibers reinforced PBCLs showed that all the BT–BF fibers strongly adhere to the PES matrix, and obscure fiber/PES interfaces are present without visible boundaries, indicating a improved interfacial interactions in this case. Thus, the mechanical, thermal and dielectric properties of the resultant PBCLs were characterized and results indicated that the BF and BT particles show enhanced synergistic effects. Following this strategy, the flexural strength and dielectric constant of BT–BF/PES blend with 40 wt% of BT were increased by 28 and 350%, respectively, in comparison with those of BF/PES composite laminates.