Oriented Thin Films of Insoluble Polythiophene Prepared by the Friction Transfer Technique

Abstract

A thin film of unsubstituted polythiophene (PT), an insoluble conjugated polymer, with molecular chains uniaxially oriented in plane was prepared by the friction transfer method. The structure of highly oriented thin films of PT was investigated using grazing-incidence X-ray diffraction (GIXD), ultraviolet–visible (UV–vis) spectroscopy, and infrared (IR) spectroscopy. The polarized UV–vis and IR spectra and GIXD measurements showed the PT molecular chains were well aligned in parallel to the friction direction. The GIXD studies clarified that the polymer backbones were aligned with very narrow distribution, such that the half-width was about 4 degrees. The degree of orientation of the PT friction-transferred film was higher compared with those of regioregular poly(3-alkylthiophene)s. Moreover, the GIXD results show a preferred orientation where the a-axis is perpendicular to the substrate plane.

Molecular arrangement in diphenylanthracene derivative films deposited under vacuum on in-plane oriented polythiophene films

“…S3 in SI, introduced alkyl substituents extend straight and parallel to the anthracene plane, and the two-plane angle between the anthracene plane and the next phenyl planes for each molecule is about 70°. Previous research has reported that DPA formed a herring-bone like packing structure; 21,22) however, diMe-DPA and diOct-DPA formed co-facial structures (Fig. 2).…”

“…Also, the obtained patterns matched those predicted by the single-crystal X-ray diffraction result previously reported. 22) On the other hand, several strong arc patterns along the meridian axis (∼Q z ) were obtained from the diMe-DPA film on the glass substrate, indicating out-of-plane orientation of the crystallites of the diMe-DPA inside the film [Fig. 3(b)].…”

“…4(a)-4(c), respectively. No patterns derived from the PT films were observed in these 2D-GIXD images 22). The 2D-GIXD patterns of the DPA film on the PT film [Fig.4(a)] were much different from those of the DPA film on the glass substrate; that is, there were arc patterns along meridian and equatorial (Q xy ) axes.…”