Ultra-high resolution imaging of thin films and single strands of polythiophene using atomic force microscopy

Abstract

Real-space images of polymers with sub-molecular resolution could provide valuable insights into the relationship between morphology and functionality of polymer optoelectronic devices, but their acquisition is problematic due to perceived limitations in atomic force microscopy (AFM). We show that individual thiophene units and the lattice of semicrystalline spin-coated films of polythiophenes (PTs) may be resolved using AFM under ambient conditions through the low-amplitude (≤ 1 nm) excitation of higher eigenmodes of a cantilever. PT strands are adsorbed on hexagonal boron nitride near-parallel to the surface in islands with lateral dimensions ~10 nm. On the surface of a spin-coated PT thin film, in which the thiophene groups are perpendicular to the interface, we resolve terminal CH 3 -groups in a square arrangement with a lattice constant 0.55 nm from which we can identify abrupt boundaries and also regions with more slowly varying disorder, which allow comparison with proposed models of PT domains.

Study of xylan and cellulose interactions monitored with solid-state NMR and QCM-D

“…The structures of cellulose in wood and pulp have been extensively studied employing CPMAS 13 C NMR spectroscopy (Van der Hart and Newman and Hemmingson 1990;Newman 1992;Newman et al 1993;Lindgren et al 1995;Larsson et al 1997;Newman 1998;Wickholm et al 1998;Larsson et al 1999;Hult et al 2000;Maunu et al 2000). Other advanced techniques such as atomic force microscopy (AFM) and QCM-D monitoring have been used as support for a better knowledge of xylan and cellulose interactions (Binnig et al 1986;Ducker et al 1991;Fatisson et al 2009;Thio et al 2011;Chen et al 2016;Mocchiuttia et al 2016;Korolkov et al 2019).…”

In Situ AFM Observation of Folded‐Chain Crystallization of a Low‐Molecular‐Weight Isotactic Poly(methyl methacrylate) in a Langmuir Monolayer at the Molecular Level

“…The high magnification imaging of polyethylene crystals by tortinal [38,39] and bimodal [40] tapping mode, and more recently the extremely high-resolution imaging of a polythiopehne thin film by the tapping mode through the low-amplitude oscillation at high eigenmodes of a cantilever [21] were reported. In addition to these static observations, recently, the crystallization process of polythiophene in a solution that was deposited on a substrate was also observed by tapping mode with a high-frequency oscillation.…”

Identification of the local electrical properties of crystalline and amorphous domains in electrochemically doped conjugated polymer thin films

“…31 Phase images provide a contrast between material properties, that cause phase shis in the oscillations of the cantilever. 46 Brighter spots in the phase images correspond to hard, more crystalline polymer, while darker areas represent so, viscoelastic, amorphous polymer. [47][48][49] The pristine lm had regions of both crystalline and amorphous domains (Fig.…”