Blue fluorescent conductive poly(9,10-di(1-naphthalenyl)-2-vinylanthracene) homopolymer and its highly soluble copolymers with styrene or 9-vinylcarbazole

A new blue fluorescent monomer, 9,10-di(1-naphthalenyl)-2-vinylanthracene, was designed and synthesized in good yield. Its homopolymer poly(9,10-di(1-naphthalenyl)-2-vinylanthracene) (P(ADN)) and soluble conductive vinyl copolymers poly[(9,10-di(1-naphthalenyl)-2-vinylanthracene)-co-styrene] (P(ADN-co-S)) and poly[(9,10-di(1-naphthalenyl)-2-vinylanthracene)-co-(9-vinylcarbazole)] (P(ADN-co-VK)) were synthesized using free radical solution polymerization. All the polymers showed high glass transition mid-point temperatures (203 to 237°C) and good thermal stabilities. The photoluminescence emission of the copolymers was similar to that of P(ADN) (with two maxima at 423 and 442nm). The lifetimes of P(ADN-co-S) (6.82 to 7.91ns) were all slightly less than that of P(ADN) (8.40ns). The lifetime of P(ADN-co-VK) increased from 7.8 to 8.8ns with an increase in VK content. The fluorescence quantum yields of P(ADN-co-S) showed an overall increasing tendency from 0.42 to 0.58. The quantum efficiencies of P(ADN-co-VK) decreased from 0.36 to 0.19 with an increase of VK fraction. With increasing S/VK content, the highest occupied molecular orbital of P(ADN-co-S)/P(ADN-co-VK) ranged from -5.58 to -5.73 eV, which was similar to that of P(ADN) (-5.71 eV). The band gaps of P(ADN-co-S) and P(ADN-co-VK) were about 2.97 eV, which were equal to that of P(ADN), and smaller than that of 2-methyl-9,10-di(1-naphthalenyl)anthracene (MADN) (3.04 eV) and poly(9-vinylcarbazole) (3.54 eV). Preliminary electroluminescence results were obtained for a homojunction device with the configuration ITO/MoO₃ (20nm)/P(ADN)/LiF (1nm)/Al (100nm), which achieved only 30-50cdm^-2, due to P(ADN) having a low mobility of 4.7×10^-8cm²V^-1s^-1 compared to that of its model compound MADN of 6.5×10^-4cm²V^-1s^-1.