Steric effect and mobility of the alkyl chain in regio-irregular poly-3-alkylthiophenes

The physicochemical properties of polyalkylthiophenes with various sidechai n length were widely investigated in order to reveal the functions of alkyl sidechains in these polymers. The effects of the side-chains on the proper ties of polyalkylthiophenes can be explained by their steric hindrance and mobility. The steric hindrance of alkyl chain affected not only the polymer ization mechanism of the monomers but also the redox potential, interchain distance, charge transport properties, and film morphology. The mobility of the side-chain influences the rate of dedoping, heat of transitions of pol ymers. The structure regio-regularity, stability of polarons/bipolarons, fi lm morphologies, and interchain interactions determine the optical and elec tric properties of polyalkylthiophenes. (C) 1999 John Wiley & Sons, Inc.