Thin films of poly(3,4-ethylenedioxythiophene) (PEDOT) were obtained by physical vapor deposition. To this end, low-molecular-weight PEDOT was synthesized by oxidative polymerization using oxygen as the oxidizing reagent with palladium acetate and copper acetate as the catalysts. The degree of polymerization was controlled by adjusting reaction time. The material can be vapor-deposited by thermal evaporation when the degree of polymerization was about 10. Formation of PEDOT thin films was confirmed by infrared spectroscopy. The optical absorption edge of the deposited film showed a redshift with increasing degree of polymerization. The electrical conductivity of the deposited film was in the range from 10-4 to 10-3 S/cm. The deposited films are expected to be in the nondoped state since the oxidizing reagent (oxygen) is unlikely to remain in the films.

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HCCI operating range can be expanded by using two fuels with different ignition characteristics. In this study, the effect of oxidation characteristics of main fuel on the operating range was investigated. Toluene and methane were used as main fuel, and DME as ignition trigger fuel. Engine experiments using a single cylinder research engine showed that methane/DME HCCI operating range extended to higher equivalence ratio compared with toluene/DME HCCI. This is explained by numerical analysis based on elementary chemical reaction model that steep heat release rate can be controlled when higher ignition temperature fuel is used, because time lag between the first stage of high temperature oxidation induced by decomposition of hydrogen peroxide (H 2 O 2 ) and onset of chain-branching reaction of main fuel increases. It was also found that the higher the reactivity with OH, the more the trigger fuel requirement, because low temperature oxidation of the trigger fuel was suppressed.