Synthesis of Carboxyl Modified Polyether Polysiloxane Surfactant for the Biodegradable Foam Fire Extinguishing Agents.

It is necessary to develop novel and efficient alternatives to fluorocarbon surfactant and prepare fluorine-free environmentally-friendly fire extinguishing agent. The carboxyl modified polyether polysiloxane surfactant (CMPS) with high surface activity was synthesized via the esterification reaction using hydroxyl-containing polyether modified polysiloxane (HPMS) and maleic anhydride (MA) as raw materials. The process conditions of the esterification reaction were optimized by orthogonal tests, and the optimum process parameters were determined as follows: reaction temperature of 85 °C, reaction time of 4.5 h, isopropyl alcohol content of 20% and the molar ratio of HPMS/MA of 1/1. The chemical structure, surface activity, aggregation behavior, foam properties, wetting properties and electron distribution were systematically investigated. It was found that the carboxyl group was successfully grafted into silicone molecule, and the conjugated system was formed, which changed the interaction force between the molecules and would affect the surface activity of the aqueous solution. The CMPS exhibited excellent surface activity and could effectively reduce the water's surface tension to 18.46 mN/m. The CMPS formed spherical aggregates in aqueous solution, and the contact angle value of CMPS is 15.56°, illustrating that CMPS had excellent hydrophilicity and wetting performance. The CMPS can enhance the foam property and has good stability. The electron distribution results indicate that the introduced carboxyl groups are more inclined towards the negative charge band, which would be conducive to weak the interaction between molecules and improve the surface activity of the solution. Consequently, new foam fire extinguishing agents were prepared by using CMPS as a key component and they exhibited excellent fire-fighting performance. The prepared CMPS would be the optimal alternative to fluorocarbon surfactant and could be applied in foam extinguishing agents.

UiO-66-Coated Mesh Membrane with Underwater Superoleophobicity for High-Efficiency Oil-Water Separation.

A UiO-66-coated mesh membrane with micro- and nanostructures was designed and successfully fabricated on steel mesh through a simple solution immersion process, exhibiting hydrophilic and underwater superoleophobic properties. It displays an outstanding oil-water separation efficiency over 99.99% with a high water permeation flux of 12.7 × 104 L m-2 h-1, so high purity water (with the residual oil content less than 4 ppm) can be readily obtained from such a simple mesh membrane from various oil-water mixtures. Its large-scale membrane production will facilitate its practical usage for the industrial and environmental water purification.

Self-assembly of Au@Ag core-shell nanocuboids into staircase superstructures by droplet evaporation.

Plasmonic nanomaterials, along with their assemblies, provide numerous applications due to their profound optical properties. In this work, we report the self-assembly of Au@Ag core-shell nanocuboids (NCs) into staircase superstructures in both vertical and horizontal orientations through two-stage droplet evaporation. Each stair is composed of a uniform well-aligned monolayer of NCs. The gap distance between NCs can be greatly shrunk to boost the corresponding surface-enhanced Raman scattering (SERS) performance using an ethanol wash method. The SERS performance of the assembled NCs is calculated by finite-difference time-domain (FDTD) simulation, and studied against the step number using 4-mercaptobenzoic acid as a Raman reporter molecule. The increasing EF with the increase of layer number proves that the plasmon mode propagates well in our uniformly aligned assemblies.

A general method for ultrathin 1D oxide nanomaterials.

By utilizing the interaction between inorganic species and organic surfactants, the ordered layered mesostructures were generated for the synthesis of the one-dimensional oxide nanomaterials. The oxide nanomaterial products which evolved from the above layered structures were demonstrated as ultrathin (less than 2 nm) one-dimensional structures with superior catalytic performance. The synthetic method based on layered structures can be extended to prepare other one-dimensional oxide nanomaterials with the same ultrathin structures.

Growth of copper oxide nanocrystals in metallic nanotubes for high performance battery anodes.

A rational integration of 1D metallic nanotubes and oxide nanoparticles has been demonstrated as a viable strategy for the production of both highly stable and efficient anodes for lithium ion batteries. We encapsulated copper oxide (CuO) nanoparticles in ultra-long metallic copper nanotubes with engineered interspaces, and explored their electrochemical properties. Such a hierarchical architecture provides three important features: (i) a continuous nanoscale metallic Cu shell to minimize electronic/ionic transmitting impedance; (ii) a unique quasi-one-dimensional structure with a large aspect ratio to reduce self-aggregation; (iii) free space for volume expansion of CuO nanoparticles and stable solid-electrolyte interphase (SEI) formation. The anode materials with such hierarchical structures have high specific capacity (around 600 mA h g-1 at a current density of 0.1 A g-1), excellent cycling stability (over 94% capacity retention after 200 cycles) and superb reversible capacity of 175 mA h g-1 at a high charging rate of 15 A g-1.