Epoxy-thiol thermosets modified by carbazole decorated hyperbranched poly(ethyleneimine) for optical applications

New epoxy-thiol thermosets containing carbazolyl moieties were prepared by adding different proportions of a hyperbranched poly(ethyleneimine) with carbazolyl terminated units to diglycidylether of bisphenol A/trimethylolpropane tris(3-mercaptopropionate) stoichiometric formulations. This carbazolyl decorated hyperbranched polymer was synthesized from commercially available hyperbranched poly(ethyleneimine) and N-glycidyl carbazole and was characterized by standard procedures.The influence of adding different proportions of the modifier to the formulation on the curing process was determined by calorimetry after the selection of the most adequate latent initiator, which was a urethane compound, named PDU-250. Its decomposition at a well-defined temperature liberates the amine that initiates the thiol-epoxy curing process.The materials obtained with different proportions of modifier were characterized by means of thermomechanical analysis. On increasing the proportion of modifier, the glass transition temperature and the damping characteristics increased, but the thermal stability and the homogeneity were reduced.The films obtained by curing the different formulations exhibited fluorescence maxima at 370-374 nm. The fluorescence quantum yields were in the range of 17-32% and they decreased with the increase of the amount of the modifier in the materials.

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