Highly stable plastic optical fibre amplifiers containing [Eu(btfa)3(MeOH)(bpeta)]: A luminophore able to drive the synthesis of polyisocyanates

The rare-earth metal organic chelate [Eu(btfa)3(MeOH)(bpeta)] (btfa, 4,4,4-trifluoro-1-phenyl-1,3-butanedionate; bpeta, 1,2-bis(4-pyridyl)ethane) has been used to dope a plastic optical fibre (POF) prepared by the bulk homopolymerization of hexamethylene diisocyanate (HMDI) catalysed by Tin(II)-2 ethylhexanoate (SnOct), to obtain a plastic optical fibre amplifier (POFA). The Eu3+ chelate, primarily added as luminophore for the amplification of the optical signal, showed an interesting co-catalytic activity in the polymerization of HMDI, that preferentially proceeded towards the formation of the highly stable polyisocyanurate trimer form thanks to its selective driving action, as demonstrated by 13C solid-state NMR. Pumping of the POFA with xenon lamps demonstrated the occurrence of stimulated emission inside the doped fibre.