Polym. Bull. https://doi.org/10.1007/s00289-018-2374-2 1 3 ORIGINAL PAPER Polyurethane network using 1‑naphthylamine embedded epoxy‑based polymer: ferric ion selective fluorescent probe Samaresh Ghosh 1  · Rajkumar Manna 1  · Swapan Dey 2 Received: 8 August 2017 / Revised: 30 April 2018 / Accepted: 15 May 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Polyurethane network 1 was prepared through curing of epoxy-based polymer bearing 1-naphthylamine units with tolylene-2,4-diisocyanate as curing agent. With ferric ions, the network was found to exhibit selective ON–OFF-type fluorescence signaling behavior even in the presence of other representative metal ions such as Na + , K + , Ag + , Cu 2+ , Zn 2+ , Co 2+ , Ni 2+ , Cd 2+ , Hg 2+ , Mg 2+ , Sr 2+ , Pb 2+ and Ca 2+ ions. Keywords Polyurethane network · Epoxy-based polymer · Chemosensor · Fe 3+ ion sensing Introduction Selective sensing of heavy or transition metal ions has attracted increasing interest because of their great importance in many in the structural, catalytic and regulatory aspects of different biosystems [1–8]. In particular, the sensing of Fe 3+ ions presents a critical issue because iron is one of the most important trace elements in the human body. Deficiency of iron is usually associated with anemia, and iron overload can also be a cause of many health problems [9–11]. Excess iron in the body is associated with hemochromatosis including neuroinflammation and progression of Alzheimer’s disease [12, 13]. To date, a variety of sensing systems have been reported for the detection of Fe 3+ ions [14–24]. However, most of them are performed in solution. * Samaresh Ghosh gsamaresh@yahoo.com 1 Department of Chemistry, Bankura Sammilani College, Kenduadihi, Bankura, West Bengal 722102, India 2 Department of Applied Chemistry, Indian Institute of Technology (Indian School of Mines), Dhanbad, Jharkhand 826004, India