Characterization of Thin Polymer Films on the Nanometer Scale with Confocal Raman AFM

Abstract

The combination of an atomic force microscope (AFM) with a Confocal Raman Microscope (CRM) has been used to study the composition of various thin films of polymer blends. The high spatial resolution of the AFM enables the morphological characterization of the polymer blends on the nanometer scale. Furthermore, when operating the AFM in Digital Pulsed Force Mode (DPFM), topographic information and local stiffness can be simultaneously recorded. This allows the material‐sensitive characterization of heterogeneous materials. Thin films where PMMA (at room temperature a glassy polymer) is blended with two different styrene‐butadiene rubbers are investigated. The presence of PMMA in both phase‐separated thin films allows the comparison of the mechanical properties of the two different rubber phases using DPFM‐AFM. When PMMA is blended with PET due to their similar mechanical properties (both are in the glassy state at room temperature) the assignment of the two phases to the corresponding polymers by AFM is rather difficult. Here, Raman spectroscopy provides additional information on the chemical composition of materials. In combination with a confocal microscope, the spatial distribution of the various phases can be determined with a resolution down to 200 nm. Therefore, the topographically different structures observed in AFM images can be associated to the chemical composition by using the Confocal Raman Microscope (CRM).

Elastic-properties measurement at high temperatures through contact resonance atomic force microscopy

“…For high temperature experiments, a poly-methyl-methacrylate and styrene-butadiene-styrene (50% PMMA -50% SBS) blend was used [17]. The blend was produced in a toluene solution, kept at 110°C for a few minutes.…”

Amorphous and crystalline calcium carbonate distribution in the tergite cuticle of moulting Porcellio scaber (Isopoda, Crustacea)

“…To get high resolution Raman images, the samples were scanned point-by-point and line-by-line, and Raman spectra between 0 and 3750 cm À1 were recorded with an integration time of 250 ms at every pixel (Pixel density: 10 spectra at 1 lm). Images were obtained analyzing the integral of specific bands above background employing the WITecProject software (Version 1_86, WITec, Ulm, Germany) (Schmidt et al, 2005). To determine the distribution of calcite, carbonate in total, and organic material we used the peak areas for the lattice vibration at 280 cm…”

Effect of alkaline treatment on cellulose supramolecular structure studied with combined confocal Raman spectroscopy and atomic force microscopy

“…Therefore, combining the chemical and morphological information from the same sample area could help the interpretation. One possibility to do this is combining confocal Raman spectroscopy and AFM-imaging, applied already for example in studies of thin polymer films (Schmidt et al 2005). First studies on extractives on cellulose surface have also been published, showing that chemical and morphological features on cellulose fibres can be identified with this technique (Ö sterberg et al 2006).…”