Highly Transparent and Water-Enabled Healable Antifogging and Frost-Resisting Films Based on Poly(vinyl alcohol)–Nafion Complexes

Highly transparent polymeric antifogging and frost-resisting films capable of conveniently healing scratches and cuts are fabricated by the dip-coating technique from a solution of hydrogen-bonded poly­(vinyl alcohol) (PVA) and Nafion complexes (denoted as PVA–Nafion), and then the as-prepared PVA–Nafion films are soaked in an aqueous NaOH solution to induce the formation of PVA crystallites. The dip-coated PVA–Nafion films can be deposited on plastic substrates such as poly­(ethylene terephthalate) and polycarbonate eyeglasses and are sufficiently flexible to endure repeated bending–unbending treatments. The PVA crystallites act as physical cross-linkers and significantly improve the stability of the PVA–Nafion antifogging films in water. Nafion has a hydrogen-bonding interaction with PVA that further improves the stability of the PVA–Nafion films. The excellent antifogging and frost-resisting capabilities of the PVA–Nafion films even under aggressive fogging and frosting conditions originate from the remarkable water-absorbing capacity of PVA in the films. The reversible hydrogen-bonding interactions between PVA and Nafion and the high mobility of the polymer chains triggered by water endow the PVA–Nafion films with the ability to rapidly and repeatedly heal scratches and cuts several hundreds of micrometers wide to restore their high transparency as well as antifogging and frost-resisting functions

Healable Antifouling Films Composed of Partially Hydrolyzed Poly(2-ethyl-2-oxazoline) and Poly(acrylic acid)

Antifouling polymeric films can prevent undesirable adhesion of bacteria but are prone to accidental scratches, leading to a loss of their antifouling functions. To solve this problem, we report the fabrication of healable antifouling polymeric films by layer-by-layer assembly of partially hydrolyzed poly­(2-ethyl-2-oxazoline) (PEtOx-EI-7%) and poly­(acrylic acid) (PAA) based on hydrogen-bonding interaction as the driving force. The thermally cross-linked (PAA/PEtOx-EI-7%)*100 films show strong resistance to adhesion of both Gram-negative Escherichia coli and Gram-positive Bacillus subtilis bacteria due to the high surface and bulk concentration of the antifouling polymer PEtOx-EI-7%. Meanwhile, the dynamic nature of the hydrogen-bonding interactions and the high mobility of the polymers in the presence of water enable repeated healing of cuts of several tens of micrometers wide in cross-linked (PAA/PEtOx-EI-7%)*100 films to fully restore their antifouling function

Multifunctional Luminescent Porous Organic Polymer for Selectively Detecting Iron Ions and 1,4-Dioxane via Luminescent Turn-off and Turn-on Sensing

The first case of selective Fe³⁺ ions and 1,4-dioxane luminescent sensor based on a porous organic polymer, POP-HT, was synthesized by reaction of tetra­(<i>p</i>-aminophenyl)­methane and chromophoric 2,5,8-trichloro-<i>s</i>-heptazine. POP-HT displayed prominent fluorescence quenching or enhancement in the presence of Fe³⁺ ion or 1,4-dioxane. Moreover, an excellent linear relationship was established between luminescent intensity and the corresponding Fe³⁺ ion or 1,4-dioxane concentration. The mechanisms of luminescence quenching and enhancement were also studied by both experiment and theoretical calculation. The results of this study suggest that POP-HT can work as an effective luminescent indicator for qualitative and quantitative detection of Fe³⁺ ions and 1,4-dioxane in aqueous solution over other metal ions and organic solvents