Ring-opening metathesis polymerization of new norbornene-based monomers containing various chromophores

Pure exo-functional norbornene monomers containing various chromophores such as fluorene, pyrene, and carbazole were successfully prepared via the Diels-Alder reaction and condensation reaction. The living ring-opening metathesis polymerization (ROMP) of a. fluorene-containing monomer, exo-2-(fluorene-9-ylcarboxymethyl)norborn-5-ene (exo-1), was observed and confirmed by the formation of a diblock copolymer and a linear relationship between the number-average molecular weight and [M]/[I] ratios ([M] = monomer concentration; [I] = initiator concentration). The synthesis and characteristics of novel fluorene-containing polymers based on pure exo-1 are reported with Grubbs catalyst I [RuCl2(CHPh)[P(C6H11)(3)](2)] with a high molecular weight of 3.18 X 10(4) in 90 s ([M]/[I] = 100). However, the ROMP of pyrene- and carbazole-containing monomers [exo-5-(pyrene methoxy carbonyl)bicyclo[2.2.1]hept-2-ene and exo-5-(carbazole ethoxy carbonyl)bicyclo[2.2.1]hept-2-ene, respectively] were carried out in a nonliving fashion. All the chromophore-containing polymers showed excellent solubility in various organic solvents, particularly in chloroform, N-methyl-2-pyrrolidinone, and 1,2-dichlorobenzene. The glass transition temperatures of polynorbornenes containing various chromophores were determined to be 80-109 degrees C (by differential scanning calorimetry) higher than that of ring-opened polynorbornene (glass transition temperature = 35 degrees C), indicating that the incorporation of the pendant aromatic moieties (e.g., fluorene, pyrene, and carbazole) could enhance the transition temperature for segmental motions of polymer chains. The photoluminescence spectra of all polymer solutions showed a strong emission in the blue region of the visible spectra. (c) 2006 Wiley Periodicals, Inc.