A solution‐processible poly(<i>p</i>‐phenylene vinylene) without alkyl substitution: Introducing the <i>cis</i>‐vinylene segments in polymer chain for improved solubility, blue emission, and high efficiency

Abstract

Abstract A soluble all‐aromatic poly(2,5‐diphenyl‐1,4‐phenylenevinylene) (2,5‐DP‐PPV) is synthesized by utilizing aromatic phosphonium and aldehyde monomers through Wittig reaction. The H 1 NMR and FTIR measurements indicate that over 50% content of cis ‐vinylene units exist in polymer backbone. The diphenyl‐substituted benzaldehyde monomer plays an important role to enhance cis ‐products (Z‐selectivity) in Wittig reactions. The twisted cis ‐segments in polymer backbone reduce the interchain interactions and enhance the solubility of such all‐aromatic PPV derivative in common organic solvents. 2,5‐DP‐PPV exhibits good solubility in common organic solvents, such as tetrahydrofuran and chloroform. The polymer film exhibits a blue light emission (λ max = 485 nm) and a very high photoluminescence efficiency of 78%. The cis ‐trans photo isomerization of this polymer in solution and the impact on the optical properties are also investigated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5242–5250, 2008