Wetting-Induced Water Promoted Flow on Tunable Liquid-Liquid Interface-Based Nanopore Membrane System

Robust Superhydrophobic Composite Fabric with Self-Healing and Chemical Durability

Superhydrophobic fabrics with multiple functions have become a research hotspot. However, it is challenging to make self-healing mechanically robust and eco-friendly superhydrophobic fabrics, which are limited by complex fabrication processes and excessive use of environmentally unfriendly solvents during fabrication. Herein, inspired by the secretion of a waxy substance from the surface of lotus leaves to restore water repellency, self-healing superhydrophobic composite fabrics (as-synthesized PA66/6-PET@Tico) are obtained by constructing a papillary TiO2 and tentacle-like fluorinated acrylate polymer (FCB015) coating on polyester-nylon composite fabrics using two-step hydrothermal method. The result indicates that PA66/6-PET@Tico with hierarchical micro/nanostructure exhibits excellent superhydrophobic and self-healing properties. Compared with FCB015 coated fabric, the contact angles (CA) of water and soybean oil rise to 172.2° and 166.8° from 137.4° and 98.8°, respectively. After mechanical abrasion, PA66/6-PET@Tico recovers a water contact angle (WCA) of 165.6° at room temperature. The WCA remains higher than 155° after 18 h of chemical corrosion. Furthermore, the bacterial inhibition rates of PA66/6-PET@Tico for Staphylococcus Aureus and Escherichia Coli are 99.90 and 98.38%, respectively. In this work, a new idea is proposed for designing a simple and effective self-healing superhydrophobic coating, expecting to promote the large-scale industrial production and application of functional surfaces.

Reorientation of Hydrogen Bonds Renders Unusual Enhancement in Thermal Transport of Water in Nanoconfined Environments

Liquid confined in a nanochannel or nanotube has exhibited a superfast transport phenomenon, providing an ideal heat and mass transfer platform to meet the increasingly stringent challenge of thermal management in developing high-power-density nanoelectronics and nanochips. However, understanding the thermal transport of confined liquid is currently lacking and is speculated to be fundamentally different from that of bulk counterparts due to the unprecedented thermodynamics of liquid in nanoconfined environments. Here, we report that the thermal conductivity of water confined in a silica nanotube is nearly 2-fold as that of bulk status. Further molecular dynamics simulations reveal that this unusual enhancement originates from the densification and reorientation of local hydrogen bonds close to the nanotubes. Thermal-confinement scaling law is established and quantitatively supported by comprehensive simulations with remarkable agreement. Our findings lay a theoretical foundation for designing nanofluidics-enabled cooling strategies and devices.

Shape and Stiffness Switchable Hydroplastic Wood with Programmability and Reproducibility

Stiffness switchable materials (e.g., supramolecular polymers, metals) that alter their shape and mechanical properties in response to specific stimuli are potentially utilized in the structural engineering field but still limited due to the use of petroleum-based synthetic monomers and large energy consumption. Herein, a sustainable and facile solvent casting strategy is proposed to fabricate the "hydroplastic wood" with shape and stiffness switchable properties via cell wall wetting, cell wall softening and subsequent moisture evaporation. Therein, a wetting agent with low surface tension and low viscosity is utilized for covering the rough surface of solid wood to form a liquid lubricating layer, thereby increasing the interfacial wettability and achieving uniform softening of the cell walls. This interface wetting treatment can easily break through the hydro-plasticization process for thick wood (Balsa wood, Ochroma lagopus Swartz, density: 0.25 g/cm3; Pinewood, Pinus armandii, density: 0.38 g/cm3). Additionally, the capillary force arising from moisture evaporation induces the self-densification of oriented cellulose nanofibrils and achieves moisture-mediated shape design capabilities through periodic saturation-dehydration. This work makes hydroplastic wood a promising candidate for engineering materials because of its combined advantages of strong durability, formability, and load-carrying capacity.

A Nanoconfined Water-Ion Coordination Network for Flexible Energy-Dissipation Devices

Water-ion interaction in a nanoconfined environment that deeply constrains spatial freedoms of local atomistic motion with unconventional coupling mechanisms beyond that in a free, bulk state is essential to spark designs of a broad spectrum of nanofluidic devices with unique properties and functionalities. Here, it is reported that the interaction between ions and water molecules in a hydrophobic nanopore forms a coordination network with an interaction density that is nearly fourfold that of the bulk counterpart. Such strong interaction facilitates the connectivity of the water-ion network and is uncovered by corroborating the formation of ion clusters and the reduction of particle dynamics. A liquid-nanopore energy-dissipation system is designed and demonstrated in both molecular simulations and experiments that the formed coordination network controls the outflow of confined electrolytes along with a pressure reduction, capable of providing flexible protection for personnel and devices and instrumentations against external mechanical impact and attack.

Non-Stop Switching Separation of Superfine Solid/Liquid Dispersed Phases in Oil and Water Systems Using Polymer-Assisted Framework Fiber Membranes

Fabricating filtration membranes with wide applicability and high efficiency is always a challenge in the precise separation of small colloidal particles under mild conditions. For this purpose, a strategy mixing supramolecular framework fiber with polymer is adopted. The fibrous assembly in the gel state provides uniform nanopores for both channel and interception and controlled wettability for lyophilic/lyophobic switching. The used polymer fills the gaps between fiber assemblies and improves the mechanical property. The composite membrane shows both under-oil superhydrophobic and underwater superoleophobic nature, which allows the conversions via in situ modulation of joystick solvents. Based on surface wetting and size-sieving, ultrafine hard nanoparticles dispersing in both hydrophobic organic solvents and water are selectively sieved. In addition, on-demand separation of water-in-oil and oil-in-water microemulsions without and with surfactants as systems containing soft droplets are realized. The smallest cut-off size of ≈3 nm is achieved for both hard and soft emulsions, while separation efficiency maintains during sustained in situ reversible switches.