•Nanofibrous composite membranes are prepared by SPEEK nanofiber mat and CS polymer.•The bicontinuous phases donate two distinct continuous pathways for proton transfer.•Interfacial interactions enrich and assemble acid–base pairs onto nanofiber surface.•The membranes achieve much higher conductivity at hydrated and anhydrous conditions.•The membranes display enhanced thermal and structural stabilities.Herein, a series of nanofibrous composite membranes (NFCMs) are designed and prepared by incorporating chitosan (CS) matrix into electrospun sulfonated poly(ether ether ketone) (SPEEK) nanofiber mats with controllable structures. Fourier transform infrared results suggest that the −SO3H groups of SPEEK and the −NH2 groups of CS assemble into acid–base pairs along the nanofiber surface. The electrostatic attractions within the pairs inhibit the chain mobility of CS and SPEEK, endowing NFCMs with reinforced thermal and structural stabilities. Besides, the attractions drive the enrichment of acid/base groups near the nanofiber surface, thus providing more proton-hopping sites in the perpendicular direction of NFCMs. Together with the conducting groups in the amorphous CS phase, these sites donate significant enhancement in proton conduction via a low-energy-barrier manner. Particularly, a hydrated conductivity of 0.153 S cm−1 is achieved by the NFCM, much higher than those of CS (0.024 S cm−1) and SPEEK (0.037 S cm−1) casting membranes. Meanwhile, the formed acid–base pairs display unique anhydrous transfer ability, affording the NFCM a high anhydrous conductivity (59.6 mS cm−1) at 120 °C. Moreover, the influence of sulfonation degree and diameter of SPEEK nanofiber on proton conductivity is systematically investigated.

Halloysite nanotubes (HNTs), natural nanotube, have been developed as a support for loading of antibacterial agents. Firstly, HNTs were modified by silane coupling agent (KH-792). And then, modified HNTs were immersed in silver nitrate solution and a complex reaction between the two amino groups of KH-792 and silver ions formed, leading to large clusters on the surface of HNTs. Finally, these silver containing clusters were converted into silver nanoparticles (Ag NPs) with about 5 nm diameter by reduction process. A new antibacterial agent, Ag NPs/HNTs, was characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and scanning transmission electron microscopy-energy dispersive X-ray analysis (STEM-EDX). The antibacterial test indicated that Ag NPs/HNTs showed good antibacterial performance against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus).Silver nanoparticles (Ag NPs) with about 5 nm diameter were homogeneously distributed and bound to the surface of HNTs. Ag NP/HNT nanocomposite powders showed good antibacterial activities against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A novel silver nanoparticle-halloysite nanotubes nanocomposite powders was prepared. ► Ag NPs with about 5 nm diameters uniformly distributed across the surface of HNTs. ► Ag NPs/HNTs nanocomposite powders showed good antibacterial activities.

Polyethyleneimine/2-hydroxypropyl trimethyl ammonium chloride chitosan/TiO2 nanoparticles/trimesoyl chloride (PEI/HACC/TiO2/TMC) positively charged composite nanofiltration (NF) membrane using polysulfone ultrafiltration membrane as support layer and TiO2 nanoparticles as modifying agent was prepared by interfacial polymerization reaction. The separation performance of the NF membrane was tested by pure water, PEG1000 solution, salt solutions, dye solutions and mixed solutions of dye and salt. The membrane structure was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). At the optimal preparation conditions of 3 wt.% PEI, 0.3 wt.% HACC, 0.9 wt.% TiO2, 1.5 wt.% TMC, reaction temperature of 20 °C and reaction time of 60 s, the NF membrane shows the high flux, the high dye rejection and the low salt rejection, which are suitable to the process of purifying raw dye.Highlights► PEI/HACC/TiO2/TMC composite nanofiltration membrane was fabricated successfully. ► HACC was used as dispersant agent of TiO2 nanoparticles. ► TiO2 was added into the nanofiltration membrane by interfacial polymerization reaction.

•N-Halamine was used as a novel antibacterial agent to fabricate membranes.•The membranes blending with SiO2@N-Halamine showed good hydrophilicity.•The membranes showed good antifouling and antibacterial properties.SiO2@N-Halamine/polyethersulfone (PES) ultrafiltration membranes were prepared by phase inversion method. The morphology, hydrophilicity, permeation performance, porosity, antifouling and antibacterial properties of the membrane were investigated. FT-IR spectra, TEM and XPS spectra results showed that SiO2 nanoparticles were prepared and modified successfully. SEM images indicated that the cross-section morphology of membrane was influenced by the introduction of SiO2@N-Halamine. The surface hydrophilicity of membranes was significantly improved after adding SiO2@N-Halamine. The filtration results indicated that the permeation properties of the hybrid membranes were significantly superior to the pure PES membrane. The water flux of the hybrid membranes increased with the additional amount of SiO2@N-Halamine increased, when the SiO2@N-Halamine content was 5%, the water flux of the membranes reached the maximum at 384.4 L·m− 2·h− 1. Moreover, the hybrid membranes showed good antifouling and antibacterial properties, which might expand the usage of PES in water treatment and also could make some potential contributions to membrane antifouling.