Alkylated hyperbranched polymers as molecular nanosponges for the purification of water from polycyclic aromatic hydrocarbons

A series of hyperbranched polymers functionalized with long aliphatic chains has been prepared and characterized. The property of films prepared from these polymers to encapsulate lipophilic polyaromatic pollutants dissolved in water has been established. The level of pyrene and fluoranthene remaining in water after treatment ranged from 1 to 30 ppb for most of the hyperbranched polymers, while for the relatively more water-soluble phenanthrene a final concentration of about 50 to 70 ppb could be attained. The inclusion formation constants determined for the polycyclic aromatics were 2.0 * 10^8-6.3 * 10^6 M^-1 for pyrene, 1.2 * 10^7-1.6 * 10^6 M^-1 for fluoranthene, and 3.8 * 10^6-4 * 10^5 M^-1 for phenanthrene. The loading capacities depend on the nature of the polycyclic aromatic compounds and the chemical structure of the parent hyperbranched polymers, ranging from 6 to 31 mg/g of polymer for fluoranthene, 15-54 mg/g for phenanthrene, and 6-35 mg/g for pyrene. Regeneration of the absorbing films was achieved by their treatment with acetonitrile.