Near-Field Infrared Imaging and Spectroscopy of a Thin Film Polystyrene/Poly(Ethyl Acrylate) Blend

Abstract

The application of broadband, near-field infrared microscopy to the characterization of the mesoscale structure of a thin film polymer blend is described. Key features of this instrument, which couples the nanoscale spatial resolution of scanning probe microscopy with the chemical specificity of vibrational spectroscopy, include broad tunability and bandwidth, parallel spectral detection for high image acquisition rates, and infrared-transparent aperture probes. Nearfield spectral transmission images of a thin film of polystyrene/poly(ethyl acrylate) acquired in the C-H stretching region are reported. An assessment of the relative importance of transmission image contrast mechanisms is a significant aim of this work. Analysis of the near-field infrared spectra indicates that the image contrast in the C-H stretching region is largely due to near-field coupling and/or scattering effects. Identification and differentiation of the operative contrast mechanisms on the basis of their relative dependence on wavelength is discussed. Analysis of the contrast attributed to absorption is consistent with the chemical morphology of this sample derived from previous chemical modification/atomic force microscopy studies.

Vibrational Spectroscopy Imaging in Polymers

“…Michaels et al [25] applied near-field IR imaging and spectroscopy to study a thin film polystyrene/poly(ethyl acrylate) blend. The instrument couples the nanoscale special resolution of scanning probe microscopy with the chemical specificity of vibrational spectroscopy.…”

FOURIER TRANSFORM INFRARED VIBRATIONAL SPECTROSCOPIC IMAGING: Integrating Microscopy and Molecular Recognition

“…Higher spatial resolution, however, may be attained by combining the microscope system with a synchrotron source or with specialized near-field apertures (7). Near-field approaches (8,9), although promising, are not currently common in laboratory settings and remain slow for mapping large sample areas. Despite the chemical specificity of IR spectroscopy, mapping techniques are not popular tools for extended sample area characterizations, particularly when many samples are to be assessed on a routine basis.…”

“…Because the SNR of single-beam and absorbance spectra are proportional to the SNRs of their interferograms, the above expression is a measure of the improvement for all spectral data when comparing the two data sets. Equation 9 can also be written in the original notation of Hirschfeld's proposal of gain ranging (40) as,…”

Polymer nanocomposites: Current understanding and issues

“…In PVDF/PMMA-co-PEA (70/30) blends, the interface region was characterised by amorphous PMMA-co-PEA component, while the surface is dominated by PVDF crystals. [114][115][116] Mechanical properties of polymer nanocomposites Tensile behaviour of polymer nanocomposites A comprehensive model to predict the experimentally observed tensile behaviour of polymer nanocomposites is not available because of the complex microscopic interactions that control the macroscopic material response and the evolution of the microstructure during deformation.…”

“…a bright field transmission electron micrograph, b selected area diffraction pattern obtained from centre region of image presented in a showing orientation relationship of (7253) CaCO3//(001)PE between crystalline part of polymer and calcium carbonate and c dark field transmission electron micrograph obtained using marked circle spot in b showing interface contrast at particle-matrix interface 112 a morphology of interface, PVDF crystals mostly dominating surface; b morphology of interface, amorphous PMMA-co-PEA component dominating interface; c morphology of subinterface, PVDF crystals and amorphous PMMA-co-PEA coexisting in subinterface[114][115][116] 11 Morphologies of PVDF/PMMA-co-PEA film at different depth from confocal microscopy…”