Supramolecular P4VP-pentadecylphenol naphthalenebisimide comb-polymer: mesoscopic organization and charge transport properties

Abstract

A supramolecular comb polymer of pentadecyl phenol (PDP) substituted naphthalenebisimide (PDP-UNBI) with poly(4-vinylpyridine) (P4VP) is reported. The mesoscopic organization within the P4VP(PDP-UNBI)_n complexes was studied using wide-angle X-ray diffraction (WXRD) techniques. The packing diagram obtained from the single-crystal XRD analysis of the PDP-UNBI crystals gave a clear picture of the initial arrangement present in self-associated PDP-UNBI alone. Correlating this with the XRD data of the hydrogen-bonded polymer complex provided insight into the probable packing of the P4VP chains within the crystalline lattice of PDP-UNBI leading to a highly ordered lamellar packing. Transmission electron microscopy (TEM) revealed the uniform mesomorphic lamellar structures in the domain range of ∼5–10 nm. Furthermore, the charge carrier mobility measurements observed from space-charge-limited current (SCLC) measurements demonstrated that transport behaviour of the hydrogen-bonded P4VP(PDP-UNBI) complex (2 × 10⁻² cm² V⁻¹ s⁻¹) was comparable to that of the crystalline naphthalenebisimide molecule itself (9 × 10⁻³ cm² V⁻¹ s⁻¹), which is a great achievement, since the complex now offers a package of solution-processable n-type semiconductor polymer with mobility equivalent to that of a small crystalline molecule.