Photochemical generation of conducting patterns in polybutadiene films

Certain polydiene rubbers can be doped by iodine to become electrically conducting. In particular, the conductivity of trans-1,4-polybutadiene can be increased by 8 orders of magnitude upon conjugation and self-doping by iodine at room temperature, whereas cis-1,4-polybutadiene cannot be made conducting by reaction with iodine under the same conditions. cis-1,4-Polybutadiene, however, can be converted into the trans-isomer by UV irradiation. On the basis of these previous findings, we have developed a simple and selective method for the photochemical generation of conducting patterns in a nonconducting (iodinated) cis-1,4-polybutadiene matrix, This was done by microlithographically patterned photoisomerization of cis-1,4-polybutadiene films followed by It-induced conjugation and self-doping of the UV exposed regions. The conducting patterns thus produced have remained stable for 10 months to date. They are colored and show strong fluorescence emission, which enables visualization of the conducting polymer regions. This facile method of conducting pattern generation could make polybutadiene attractive for microelectronic applications.