New Cyclic Olefin Copolymer for the Preparation of Thermally Responsive Luminescent Films

Polymer films with optical properties as indicators to thermal stress were obtained through the controlled dispersion of moderate amounts (0.1 wt.-%) of the 4,40-bis(2-benzoxazolyl)- stilbene (BBS) dye into a new semicrystalline ethylene-norbornene (E-co-N, N content of 15.3 mol.-%) copolymer characterized by a glass transition temperature (Tg) of about 64 8C. All the pristine films showed optical characteristics com- ing from noninteracting BBS chromophores. In contrast permanent optical changes were detected after film annealing at a T Tg due to the variation of the BBS supramolecular structure. The easy modulation of the optical features of polymer films by thermal perturbations suggests applications as threshold temperature visual indicators in thermoplastic materials.