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Combination of atomic force microscopy, scanning near-field microscopy and confocal Raman imaging enables nondestructive, physical and chemical characterization of heterogeneous materials at high resolution.
Теги: atomic force microscopy raman imaging scanning near-field microscopy атомно-силовая микроскопия конфокальная рамановская спектроскопия сканирующая ближнепольная оптическая микроскопия
Polymers play an essential role in modern materials science. Due to their widely varying mechanical and chemical properties they are used in almost every field of application and remain a dynamic component of the development of new materials with demanding requirements. For many of these endeavors, knowledge of the morphology and chemical composition of heterogeneous polymeric materials on a sub-micrometer scale is crucial. We used a combination of Atomic Force Microscopy (AFM), Scanning Near-field Microscopy (SNOM) and confocal Raman imaging to study the composition of a three-component polymer blend.
While AFM operated in tapping mode recorded topographic information and local mechanical characteristics, SNOM detected optical properties with resolution far below the diffraction limit and Raman imaging revealed the molecular composition of the sample. Coupling these methods, correlated AFM – SNOM – confocal Raman microscopy, opens new avenues for the development and analysis of advanced polymeric materials that require a detailed understanding of physical and chemical properties on a sub-micrometer scale.
The phase separation of a thin film blend of 1:1:1 polysterene (PS), styrene-butadiene-rubber (SBR) and ethyl-hexyl acrylate (EHA) was analyzed with a WITec alpha 300 RAS microscope featuring all three analysis methods integrated within one instrument. The sample, spin coated onto glass, remained in place throughout, allowing for images to be correlated. The WITec Control software enables a comprehensive evaluation of the acquired data and the generation of depth profiles.
The topography of the sample measured with AFM reveals a three-level structure (a) while the simultaneously recorded phase image (b) shows a fine netlike texture at the lowest topographic level, material containing small spheres in the intermediate layer and an amorphous pattern in the uppermost substance. The SNOM image acquired from the same sample section indicates that the thinnest areas of the samples are opaque (c). These areas contain EHA only, as can be inferred from the Raman image (d) that was generated from the Raman spectra (e). The uppermost features of the sample appear to be PS, which is known to form spheres. The perfect correlation of topography, phase separation, SNOM and molecular composition is illustrated by the overlay of the AFM phase and Raman images (f).
We correlated all structural, physical and chemical data and in our interpretation the EHA forms the lowermost layer on the microscope slide. It is covered by a layer of SBR as indicated by the blended (EHA-SBR) Raman spectrum. PS spheres are submerged in and protrude out of this double layer polymer film.
The combination of AFM, SNOM and confocal Raman imaging in a single instrument enables easy-to-use, nondestructive, physical and chemical characterization of heterogeneous materials at very high resolution. ■
While AFM operated in tapping mode recorded topographic information and local mechanical characteristics, SNOM detected optical properties with resolution far below the diffraction limit and Raman imaging revealed the molecular composition of the sample. Coupling these methods, correlated AFM – SNOM – confocal Raman microscopy, opens new avenues for the development and analysis of advanced polymeric materials that require a detailed understanding of physical and chemical properties on a sub-micrometer scale.
The phase separation of a thin film blend of 1:1:1 polysterene (PS), styrene-butadiene-rubber (SBR) and ethyl-hexyl acrylate (EHA) was analyzed with a WITec alpha 300 RAS microscope featuring all three analysis methods integrated within one instrument. The sample, spin coated onto glass, remained in place throughout, allowing for images to be correlated. The WITec Control software enables a comprehensive evaluation of the acquired data and the generation of depth profiles.
The topography of the sample measured with AFM reveals a three-level structure (a) while the simultaneously recorded phase image (b) shows a fine netlike texture at the lowest topographic level, material containing small spheres in the intermediate layer and an amorphous pattern in the uppermost substance. The SNOM image acquired from the same sample section indicates that the thinnest areas of the samples are opaque (c). These areas contain EHA only, as can be inferred from the Raman image (d) that was generated from the Raman spectra (e). The uppermost features of the sample appear to be PS, which is known to form spheres. The perfect correlation of topography, phase separation, SNOM and molecular composition is illustrated by the overlay of the AFM phase and Raman images (f).
We correlated all structural, physical and chemical data and in our interpretation the EHA forms the lowermost layer on the microscope slide. It is covered by a layer of SBR as indicated by the blended (EHA-SBR) Raman spectrum. PS spheres are submerged in and protrude out of this double layer polymer film.
The combination of AFM, SNOM and confocal Raman imaging in a single instrument enables easy-to-use, nondestructive, physical and chemical characterization of heterogeneous materials at very high resolution. ■
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