Bipolar Conducting Polymers: Blends of p-Type Polypyrrole and n-Type Ladder Polymer.
ROCHESTER UNIV NY DEPT OF CHEMICAL ENGINEERING
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Bipolar conducting polymers, in which both hole and electron transport contribute to electronic conductivity, have been explored by chemical template synthesis of p-type polypyrrole PPy in the matrix of an n-type conjugated ladder polymer, polybenzimidazolebenzophenanthroline BBL. Transmission electron microscopy images of the conducting polymer blends show that 5-20 nm diameter by 100-180 nm long rodlike PPy particles are randomly and homogeneously distributed in the BBL matrix, with connectivity of the PPy phase occurring at a volume fraction of about 0.17. The volume fraction dependence of conductivity of the BBLPPy blends did not exhibit a percolation threshold at volume fractions as low as 0.007 nor can it be described by percolation-type effective medium theory. Room temperature conductivities as high as 60-70 Scm were observed in the blends compared to 2 Scm in pure PPy. The enhanced conductivity and the non-percolation nature of these blends originate from bipolar charge transport involving both conjugated polymer components of the blends. Existence of the oxidized p-type polypyrrole and reduced n-type BBL that facilitate bipolar charge transport in these blends was established by cyclic voltammetry.
- Polymer Chemistry
- Physical Chemistry
- Electricity and Magnetism