Shaokun Song

Hydrophilic Magnetofluorescent Nanobowls: Rapid Magnetic Response and Efficient Photoluminescence

Multifunctional integration based on a single nanostructure is emerging as a promising paradigm to future functional materials. In this paper, novel magnetofluorescence nanobowls built with ferroferric mandrel and quantum dots exoderm is reported. Magnetic mandrels are stacked into nanobowls though hydrophobic primary Fe3O4 nanocrystals dragged into anion polyelectrolyte aqueous solution via forced solvent evaporation. Bright luminescence core/shell/shell CdSe/CdS/ZnS quantum dots (QDs) are modified with cationic hyperbranched polyethylenimine (PEI). Through electrostatic interactions, positively charged PEI-coated QDs are anchored on the surface of magnetic mandrel. Under this method, the luminescence of QDs is not quenched by magnetic partners in the resultant magnetoflurescence nanobowls. Such magnetoflurescence nanobowls exhibit high saturation magnetization, superparamagnetic characteristics at room temperature, superior water dispersibility, and excellent photoluminescence properties. The newly developed magnetoflurescence nanobowls open a new dimension in efforts toward multimodal imaging probes combining strong magnetization and efficient fluorescence in tandem for biosensors and clinical diagnostic imaging.

A high-efficiency ultrafiltration nanofibrous membrane with remarkable antifouling and antibacterial ability

Fouling in ultrafiltration (UF) membranes for water treatment results in a decrease in filtration efficiency and a deterioration in water quality. In this work, a self-supporting hydrophilic nanofibrous membrane was obtained by mixing multi-arm amphiphilic fluxible poly(p-phenylene terephthalamide) (f-PPTA) with poly(vinylidene fluoride) (PVDF) in solution followed by an electrospinning process. Notably, f-PPTA migrated to the nanofiber surface owing to its self-mobility and induction by the electric field force. Therefore, hydrophilic chains provided by f-PPTA greatly increased the wettability of the whole membrane, since f-PPTA was introduced during the membrane preparation. The multi-arm f-PPTA acted as the water channel in the nanofibrous membrane, accelerating the flow of water molecules through the membrane. The increasing electric field force caused by f-PPTA had a great effect on regulating the nanofiber diameter and pore size of the nanofibrous membrane, which further influenced the filtration performance. Consequently, the pure water flux reached 8.3 × 104 L (m2 h)−1 at 0.2 MPa when the f-PPTA addition amount was 20 wt% of PVDF, which was 2.3 times higher than that of the neat PVDF nanofibrous membrane. Undoubtedly, amphiphilic f-PPTA proved to show excellent compatibility with PVDF, which avoided the problems of hydrophilic polymers being washed away easily and inorganic nanoparticle aggregation, and hence the modified nanofibrous membranes exhibited a relatively stable filtration flux. After operation for 6 h the membrane retained approximately 89% of the initial flux and protein rejection also remained at 98.7%. The membrane with more hydrophilic chains improved the antifouling ability preventing the membrane surface and inside pore structure from being fouled. Additionally, as a polymer-based antibacterial agent, f-PPTA also played a key role in improving the antibacterial activity. Overall, the membrane achieved a comprehensive performance of a sustainable high permeation flux, and remarkable antifouling and antibacterial activities, thus becoming a promising candidate for UF applications in water treatment.

Effects of poly-( p -phenylene terephthamide) powder coated with polydopamine on ethylene-propylene-diene-terpolymer grafted maleic anhydride

In this paper, we reported a technique for the surface modification of poly-(p-phenylene terephthamide) (PPTA) powder coated with polydopamine (PDOPA). We used air oxidation to self-polymerize dopamine (DOPA) to ensure that the PPTA powder was coated. Our results indicate that the modified surface of PPTA powder enhances compatibility with the polymer matrix without damaging its structure. Additionally, it is possible to control the coating thickness of PDOPA by regulating the reaction time. The modified PPTA powder improved the comprehensive property of ethylene-propylene-diene-terpolymer grafted maleic anhydride (EPDM-g-MAH), and it proved that this method can enhance the strength and electric insulativity of EPDM-g-MAH.