Mussel-Inspired Hybrid Coatings that Transform Membrane Hydrophobicity into High Hydrophilicity and Underwater Superoleophobicity for Oil-in-Water Emulsion Separation

We first report here mussel-inspired, hybrid coatings formed in a facile manner via simultaneous polymerization of mussel-inspired dopamine and hydrolysis of commercial tetraethoxysilane in a single-step process. The hybrid coatings can firmly adhered on hydrophobic polyvinylidene fluoride (PVDF) substrate, and the hydrophilicity of the coating can be tuned by adjusting silane concentration. The reason for the changed hydrophilicity of the coating is disclosed by a series of characterization, and was applied to rationally design optimized hybrid coatings that transform commercial PVDF microfiltration (MF) membrane hydrophobicity into high hydrophilicity with excellent water permeability and underwater superoleophobicity for oil-in-water emulsion separation. The PVDF MF membrane decorated with optimized coatings has ultrahigh water flux (8606 L m^–2 h^–1 only under 0.9 bar, which is 34 times higher than that of pristine membrane), highly efficient oil-in-water emulsion separation ability at atmospheric pressure (filtrate flux of 140 L m^–2 h^–1) and excellent antifouling performance. More importantly, these membranes are extremely stable as underwater superoleophobicity are maintained, even after rigorous washings or cryogenic bending, disclosing outstanding stability. The simplicity and versatility of this novel mussel-inspired one-step strategy may bridge the material-induced technology gap between academia and industry, which makes it promising for eco-friendly applications

Tailoring Physical Aging in Super Glassy Polymers with Functionalized Porous Aromatic Frameworks for CO₂ Capture

A series of chemically functionalized porous aromatic frameworks (PAFs) have been synthesized and deployed within mixed-matrix membranes for gas separation. This series of PAFs delivered for the first time simultaneous control of selective gas transport and physical aging within the membranes. New composites including native and metalated fullerenes were also prepared, and the composites exhibited exceptional increases in their porosity, which in turn resulted in ultrafast gas transport. CO₂ permeability following PAF-1-Li₆C₆₀ infusion within poly­(trimethylsilylpropyne) was as high as 50 600 Barrer, a 70% improvement. Remarkably, just 9% of this permeation rate diminished after 1 year of physical aging, compared to 74% in the native polymer. A series of characterization techniques revealed this phenomenon to be due to intercalation of polymer chains within the PAF pores, the strength of which is controlled by the levels of chemical functionalization and porosity. The membranes were exploited for gas separations, in particular the stripping of CO₂ from natural gas

Post-Synthetic Annealing: Linker Self-Exchange in UiO-66 and Its Effect on Polymer–Metal Organic Framework Interaction

Post-synthetic exchange (PSE) and defect engineering have emerged as powerful techniques for tuning the properties and introducing novel functionality to metal organic frameworks (MOFs). Growing evidence suggests that each technique plays a key role in the mechanism of the other: linker coordination chemistry is pivotal to defective frameworks, while defect sites can help initiate PSE. Here, the intersection of these approaches is explored by exchanging an MOF with linkers already present within the framework. Post-synthetic annealing (PSA) modifies an MOF’s properties by redistributing the framework’s mixture of bound linker/modulator species. Using changes to the polymer-additive interactions in poly-1-trimethylsilyl-1-propyne nanocomposites observed through aging, we demonstrate that PSA causes one linker species to preferentially accumulate on the MOF’s crystal surface. Reaction conditions are shown to affect molecular composition of the resulting annealed UiO-66 MOFs, a finding explained through established reaction constants. This work simultaneously reveals intricacies of post-synthetic modification chemistry and presents a facile means of tuning MOFs and MOF nanocomposites