Polyester Nanofilms with Enhanced Polyhydroxyl Architectures for the Separation of Metal Ions from Aqueous Solutions

Designing advanced adsorption materials from molecular structure is significant to separation science and technology. We develop an intriguing strategy to prepare free-standing polyester nanofilms with enhanced polyhydroxyl architectures. The key to this strategy is to manipulate polyphenols on the surface of a thermoreversible hydrogel substrate by a synergetic application of metal–organic coordination, interfacial polymerization, and disassembly. The nanofilms with thicknesses ranging from several nanometers to hundreds of nanometers were successfully prepared and systematically analyzed. Attenuated total reflection infrared spectroscopy and ζ-potential analysis show that the polyester nanofilms have asymmetrically enhanced polyhydroxyl architectures owing to the preprotection of hydroxyl groups by the metal–organic coordination. The adsorption properties of the polyester nanofilms to a variety of metal ions were further investigated with an emphasis on clarifying its potential in water purification. Strikingly, the polyester nanofilms show exceptional properties as sorbents with high adsorption capacity and ultrafast adsorption rates to those tested metal ions. The initial adsorption rates of the polyester nanofilms to boron and lead(II) even reach 6.65 and 149.4 mg·g–1·s–1, respectively, which are 10 to 120 times higher than those of reported membranes and commercial resins. The preparation strategy reported here is universal, which could be used to develop a series of promising adsorption materials through the adoption of different polyphenols and polyamines.