Functional polymers: scanning force microscopy insights

Abstract

Scanning force microscopy (SFM) and related techniques make it possible to visualize polymer systems with a molecular resolution. Beyond imaging, they also enable the unveiling of a variety of (dynamic) physico-chemical properties of both isolated polymer chains and their supramolecular architectures, including structural, mechanical and electronic properties. This article reviews recent progress in the use of SFM on polymers, with a particular emphasis on the mechanical properties of copolymers and single polymer chains, as well as on the bottom-up fabrication of supramolecular polymeric (helical) nanostructures in particular based upon pi-conjugated macromolecules as building blocks for nanoelectronics. Through a detailed understanding of the polymer behavior, we propose solutions for the generation of organic functional (nano)systems.

Probing Local Surface Potential of Quasi‐One‐Dimensional Systems: A KPFM Study of P3HT Nanofibers

“…Tapping Mode Scanning Force Microscopy (SFM) [31][32][33][34] was employed recording both the height signal (output of the feedback signal) and the phase signal (phase lag of the tip oscillation respect to the piezo-oscillation). While the first type of images provides a topographical map of the surface, the latter is extremely sensitive to structural heterogeneities on the sample surface, being therefore ideal to identify different components in a hybrid film.…”

Probing the Local Conformation within π‐Conjugated One‐dimensional Supramolecular Stacks using Frequency Modulation Atomic Force Microscopy

“…[13] While scanning tunneling microscopy is extremely powerful for investigating 'face on' molecular layers, [14][15][16][17][18] it is rarely applicable to 'edge on' functional supramolecular assemblies, and is restricted to conducting surfaces. Atomic force microscopy (AFM) constitutes a more universal approach and has been widely applied in ambient conditions in intermittent contact (also called amplitude modulation mode, AM-AFM) to characterize the microscopic morphology of solution-processed p-conjugated oligomers and polymers deposited in thin films on conducting and insulating surfaces, [19][20][21][22] such as the substrates used for the gate dielectric in OFETs. The resolution achieved by AFM is typically a few nanometers.…”

“…However, the exact nature of the molecular packing within functional p-conjugated assemblies often remains unknown, because of the limits in spatial resolution of AFM in the amplitude modulation mode. For instance, images reveal the fibrillar organization of the stacks [19][20][21][22] but provide no information on their internal structure.…”

Photochemically Initiated Single Polymer Immobilization

“…[7][8][9] Among these techniques are single molecule fluorescence microscopy, scanning force microscopy, laser scanning confocal microscopy (LSCM), scanning nearfield optical microscopy (NSOM), and optical tweezers. Atomic force microscopy (AFM) in particular is highly versatile for imaging, manipulating, and stretching single polymer molecules in a non-invasive manner and under mild conditions.…”