Fabrication of hydrophobic NiFe2O4@poly(DVB-LMA) sponge via a Pickering emulsion template method for oil/water separation

Magnetic Hyperporous Elastic Material with Excellent Fatigue Resistance and Oil Retention for Oil-Water Separation

Oily wastewater has caused serious threats to the environment; thus, high-performance absorbing materials for effective oil-water separation technology have attracted increasing attention. Herein, we develop a magnetic, hydrophobic, and lipophilic hyperporous elastic material (HEM) templated by high internal phase emulsions (HIPE), in which free-radical polymerization of butyl acrylate (BA) and divinylbenzene (DVB) is employed in the presence of poly(dimethylsiloxane) (PDMS), lecithin surfactant, and modified Fe3O4 nanoparticles. The adoption of the emulsion template with nanoparticles as both stabilizers and cross-linkers endows the HEM with biomimetic hierarchical open-cell micropores and elastic cross-linked networks, generating an oil absorbent with outstanding mechanical stability. Compressive fatigue resistance of the HEM is demonstrated to endure 2000 mechanical cycles without plastic deformation or strength degradation. By exploiting the synergistic effect of hierarchical structures and low-surface-energy components, the resulting HEM also possesses excellent and robust hydrophobicity (water contact angle of 164°) and good oil absorption capacity, in which Fe3O4 nanoparticles lead to convenient magnetically controlled oil recyclability as well. Notably, the unique biomimetic microporous structure demonstrates superior oil retention capacity (>95% at 1000 rpm and >60% at 10,000 rpm) over the state-of-the-art porous materials for a diverse variety of oils to reduce the risk of secondary oil leakage, along with good recoverability by squeezing owing to the excellent compression resilience. These excellent performances of our HEM provide broad prospects for practical applications in oil-water separation, energy conversion, and smart soft robotics.

Preparation of robust silicone superhydrophobic and antibacterial textiles using the Pickering emulsion method

This study aimed to prepare textiles with superhydrophobic and antibacterial properties using the Pickering emulsion impregnation method. Cellulose nanocrystals were synergistically employed with dimethyloctadecyl[3-(trimethoxysilyl)-propyl] ammonium chloride as the solid surfactant, and hydrogenated (PHMS) and hydroxyl (MSDS) polysiloxane were used as the oil phase for emulsification. The emulsions were mixed and diluted in specific proportions, and the superhydrophobic and antibacterial textiles were prepared through fabric impregnation-drying strategies. The study optimised factors such as emulsion ratio and surfactant dosage. Results demonstrated that the nanoscale rough structure prepared using Pickering emulsion exhibited remarkable superhydrophobicity with contact and rolling angles of 163.1° ± 0.5° and 7.2° ± 0.2°, respectively. This effect was achieved when the ratio of PHMS emulsion to MSDS emulsion was maintained at 1:2 and the surfactant dosage was set at 2 %. The superhydrophobicity of textiles was maintained even after three washing cycles and 50 abrasion cycles, demonstrating excellent mechanical durability. The developed textiles also exhibited excellent oil/water separation ability, reliable recyclability and stability. Moreover, they demonstrated excellent self-cleaning and antibacterial capabilities. Thus, these valuable functionalities hold the potential to considerably improve the practical feasibility of superhydrophobic textiles in various application scenarios.

A 3D smart wood membrane with high flux and efficiency for separation of stabilized oil/water emulsions

Oily sewage discharged from indiscriminate industrial and frequent oil spills have become a serious global problem. There is an urgent need to separate stable oil/water emulsions by efficient and environmentally friendly methods. Membrane separation technology has the advantages of low energy consumption and low cost, thus is an effective solution to the problems of oily wastewater. However, the manufacture of multifunctional membranes with high efficiency, high flux and self-cleaning using renewable materials remains a challenge. Herein, three-dimensional (3D) smart membranes with switchable superhydrophobic-hydrophilic surfaces were prepared by grafting photo-responsive poly-spiropyran (PSP) on wood-based substrates via surface atom transfer radical polymerization. This novel membrane can efficiently separate stabilized water-in-oil and oil-in-water emulsions due to reversible hydrophilic-hydrophobic transition by switching UV and visible light irradiation. Remarkably, after immobilization, the PSP grafted on the wood substrate exhibited a faster photo response effect than the free spiropyran (SP). More importantly, the prepared 3D smart membranes showed exceptional high flux (4392 L•m^-2•h^-1) and efficiency (above 99.99 %), good cycle stability (99.99 % after 12 times) and durability (available for at least 60 days) for the separation of surfactant-stabilized water-in-oil emulsions. This work opens a new avenue for the design of functional biomass-derived membranes for efficient and sustainable oily wastewater treatment with high flux, easy scale-up, and green regeneration.

Peptide hydrogel based sponge patch for wound infection treatment

Dressing with the function of anti-wound infection and promoting skin repair plays an important role in medicine, beauty industry, etc. In terms of anti-wound infection, traditional dressings, such as gauze, have problems such as excessive bleeding in the process of contact or removal, and slow wound healing due to poor biological compatibility. The development of new functional and biocompatible dressings has essential application value in biomedical fields. In this study, a new type of dressing based on polypeptide functional sponge patch was constructed. The porous sponge patch is made of antimicrobial peptide and medical agarose through gel and freeze-drying technology. In vitro antibacterial experiments and small animal skin wound infection model experiments show that the porous sponge has excellent antibacterial and anti-skin infection activities, as well as the function of promoting wound healing.

Emulsion-templated porous polymers: drying condition-dependent properties

Macroporous materials templated using high internal phase emulsions (HIPEs) are promising for various applications. To date, new strategies to create emulsion-templated porous materials and to tune their properties (especially wetting properties) are still highly required. Here, we report the fabrication of macroporous polymers from oil-in-water HIPEs, bereft of conventional monomers and crosslinking monomers, by simultaneous ring-opening polymerization and interface-catalyzed condensation, without heating or removal of oxygen. The resulting macroporous polymers showed drying condition-dependent wetting properties (e.g., hydrophilicity-oleophilicity from freezing drying, hydrophilicity-oleophobicity from vacuum drying, and amphiphobicity from heat drying), densities (from 0.019 to 0.350 g cc^-1), and compressive properties. Hydrophilic-oleophilic and amphiphobic porous polymers turned hydrophilic-oleophobic simply by heating and protonation, respectively. The hydrophilic-oleophobic porous polymers could remove a small amount of water from oil-water mixtures (including surfactant-stabilized water-in-oil emulsions) by selective absorption and could remove water-soluble dyes from oil-water mixtures. Moreover, the transition in wetting properties enabled the removal of water and dyes in a controlled manner. The feature that combines simply preparation, tunable wetting properties and densities, robust compression, high absorption capacity (rate) and controllable absorption makes the porous polymers to be excellent candidates for the removal of water and water-soluble dyes from oil-water mixtures.

One-pot facile synthesis of PDMS/PDMAEMA hybrid sponges for surfactant stabilized O/W emulsion separation

Hydrophobic/oleophilic sponges are excellent absorbent materials for oil contaminant removal. However, the application is limited in dealing with surfactant stabilized O/W emulsions. The water in the emulsion isolates the contact between the sponge and oil droplets. Consequently, the oil absorption efficiency is not ideal. Herein, to improve the oil absorption efficiency from anionic surfactant stabilized O/W emulsions, water responsive hybrid sponges were reported. To prepare such sponges, water soluble poly(N,N-dimethylaminoethylmethacrylate) (PDMAEMA) was introduced into polydimethylsiloxane (PDMS) sponges using table salt as a template and multi-walled carbon nanotubes (MWCNTs) as mechanical reinforcement in a one-pot method. Upon contact with an O/W emulsion, the water soluble PDMAEMA chain rose to the surface of the sponge, turning the hydrophobic surface into hydrophilic. Next, the tertiary amine groups in PDMAEMA ionized in water and carried positive charges which would cause the coagulation of oil droplets. Finally, the coagulated oil droplets were absorbed immediately by the oleophilic inner part of the sponge through the wicking effect. As a result, a Janus interface was generated in situ and sustained. Such material design synergistically contributed to a satisfactory hexadecane (HD) absorption efficiency of 178 ± 4% in 25 min. In contrast, the PDMS-MWCNT_1.0% sponge could only absorb 9.8 ± 0.2% HD. Moreover, these sponges also presented robust mechanical performance and reusability, offering a new route for oil/water separation and oil pollution remediation in open water.

Degradable and processable polymer monoliths with open-pore porosity for selective CO2 and iodine adsorption

A task-specific design of biodegradable and processable porous polymers is one of the primary requisite for their efficient day-to-day use to minimize polymer waste. Herein, a surfactant (or additive)-free method is reported for the synthesis of a processable and degradable aliphatic open-pore porous polyelectrolyte monolith for the removal of gaseous pollutants such as iodine and CO2. This is achieved via a colloidal templating method. In the 1st stage, cationic colloidal nanoparticles containing reactive amines and acrylamide groups were formed via the phase separation of hyperbranched polyaminoamides in water (sol). These cationic nanoparticles (which acted as both templates and macromers) further reacted to form a gel, which upon freeze-drying leads to the formation of a polymer monolith with an open-pore porous morphology and hierarchical porosity throughout its structure. During gelation, the shape of the monolith can be controlled using suitable templates and a similar strategy was used to prepare porous thin films. The monolith has shown excellent iodine adsorption ability (5000 mg g-1 in the vapor phase and 2663 mg g-1 in the solution phase) with good reusability and CO2 adsorption ability (60 mg g-1), with CO2/CH4 and CO2/N2 selectivities of 18.5 and 6.7, respectively. The degradability of the materials was studied in detail at different pH, confirming their easy degradability in aqueous solutions and a higher degradability at basic pH.