▪ Abstract Applications of state-of-the-art atomic force microscopy methods to the elucidation of the surface and near-surface structure of polymeric solids are described. Contact, tapping, force modulation, frictional force, and other modes of atomic force microscopy are described, and recent results are summarized. Conformational and chain order, crystalline order, polymer crystals, lamellar structures, lamellar surfaces, fold surfaces, and fibers and films with highly oriented molecules all yield important information. Controlled deformation of polymer surfaces, both reversible and irreversible, with the atomic force microscope, provides a wealth of information about mechanical properties on a nanometer scale. The observation of phase-separated regions and of polymer crystals lying below a smooth surface shows that not only topography but also elastic inhomogeneity can be observed in great detail with the atomic force microscope. This is a rapidly developing field, and some indications of future develo...

Characterization of polymer surfaces with atomic force microscopy

Scanning probe microscopy of organic and polymeric films: from self-assembled monolayers to composite multilayers

The precursor fiber quality has a large impact on carbon fiber processing in terms of its performance, production yield, and cost. Polyacrylonitrile precursor fibers have been used commercially to produce strong carbon fibers with average tensile strength of 6.6 GPa. There is a scope to improve the average tensile strength of carbon fibers, since only 10% of their theoretical strength has been achieved thus far. Most attempts to increase the tensile strength of carbon fibers have been made during the conversion of precursor fiber to carbon fiber. This review highlights the potential opportunities to enhance the quality of the polyacrylonitrile-based precursor fiber during polymer synthesis, spinning, and postspinning. These high-quality precursor fibers can lead to new generation carbon fibers with improved tensile strength for high-performance applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43963.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/app.43963

Producing high-quality precursor polymer and fibers to achieve theoretical strength in carbon fibers: A review

Double-stranded poly(dG)–poly(dC) and triple-stranded poly(dG)–poly(dG)–poly(dC) DNA were deposited on the modified surface of highly oriented pyrolitic graphite (HOPG) and visualized using atomic force microscopy with high-resolution (radius of ~1 nm) tips. The high resolution attained by this technique enabled us to detect single-stranded regions in double-stranded poly(dG)–poly(dC) and double-stranded and single-stranded regions in poly(dG)–poly(dG)–poly(dC) triplexes, as well as to resolve the helical pitch of the triplex molecules. We could also follow the reaction of G-strand extension in poly(dG)–poly(dC) by the Klenow exo− fragment of DNA polymerase I. This approach to molecular visualization could serve as a useful tool for the investigation of irregular structures in canonical DNA and other biopolymers, as well as studies of the molecular mechanisms of DNA replication and transcription.

https://iopscience.iop.org/article/10.1088/0957-4484/18/22/225102/pdf

High-resolution atomic force microscopy of duplex and triplex DNA molecules

The creation of a new family of scanning probe techniques is one of the most exciting events in surface analysis in the last decade. The unique results have been achieved with the main representatives of these techniques—scanning tunneling microscopy (STM) and atomic force microscopy (AFM)-in the visualization of topographic and electronic features in the atomic scale. These new methods attracted many research teams. In a relatively short time, surfaces of different materials (metals, semiconductors, inorganic layered compounds, organic layers, single crystals, polymers, and biological objects) were examined by these techniques. This review is based on ambient conditions STM and AFM experiments conducted at the Materials Research Center of Freiburg University. Two main aspects of the results of imaging transition metal chalcogenides and halides, conductive organic salts, and polymers are emphasized. One is related to interpretation of the images, with the separation of the contributions of the el...

Surface Characterization of Materials at Ambient Conditions by Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM)

Results of Atomic Force Microscopy (AFM) on carbon fibers from polyacrylonitrile and pitch are presented in comparison with Scanning Electron Microscopy (SEM) and Scanning Tunneling Microscopy (STM) images Single fiber surfaces and their crosssections have been imaged on scales from microns to nanometers Morphological details beyond the resolution of SEM were revealed by AFM and STM Grain-type structure was verified on surface of numerous nanofibrils orlented along the main fiber direction Grains are bigger on pitch-based fibers generally, and on fibers of both types after treatment at higher temperatures In the atomic scale AFM images traces of graphitic structure were recorded AFM artefacts on rough surfaces are demonstrated ac19920414

A. Ya. Gorenberg

Papers

Atomic force microscopy on polymers and polymer related compounds