James M. Pearson

Electrical properties of a series of carbazole polymers

The electrical transport properties of three vinyl carbazole polymers have been examined to determine if the observed variations in NMR chemical shifts resulting from inter−ring shielding effects could be correlated with carrier mobilities in the polymers. Drift mobilities were measured in films of the polymers overcoated with thin layers of amorphous Se using a xerographic discharge technique. Under the conditions for observing trap free space charge limited currents the hole mobilities were calculated from Child’s law. The three polymers exhibited mobilities varying as the square of the electric field over the range of fields examined. P2VK which showed the overall largest upfield shift of the aromatic protons exhibited a mobility of 1.4×10−6 cm2/V⋅sec at a field of 4×105 V/cm. PVK which exhibit an intermediate degree of shielding had a mobility of 1.4×10−7 cm2/V⋅sec and P3VK which exhibits the smallest shielding effect had a mobility of 2.4×10−8 cm2/V⋅sec both at equivalent fields. Although P2VK showed...

Ionic Polymerization of Vinyl Aromatic Monomers

Abstract The ionic polymerization of vinyl monomers possessing aromatic and heterocyclic functional groups has not been studied in any systematic fashion. Only in a few isolated cases have detailed mechanistic and structural studies been reported. The anionic polymerization of a number of vinylanthracene monomers has recently been investigated and some rationalization of this system is presented. The cationic and anionic polymerization of the N-, 3-, and 2-vinylcarbazole series of monomers is discussed in some detail. The important role of vinyl aromatic/vinyl heterocyclic monomers, i.e., diphenylethylene and the vinylcarbazoles, in elucidating the mechanistic aspects of cationic polymerization, “change transfer” polymerization, and photoionic polymerization is considered.