Resolving Nanocomposite Interfaces via Simultaneous Submicrometer Optical‐Photothermal Infrared‐Raman Microspectroscopy
Alexander J. Wang, Eoghan Dillon, Surendra Maharjan, Kang‐Shyang Liao, Brian McElhenny, Tian Tong, Shuo Chen, Jiming Bao, Seamus A. Curran
Abstract
Abstract Nanocomposite materials are assuming increasingly important roles across contemporary materials science. Analytical characterizations and visualizations of nanoscale interphases/interfaces are critical to development of novel multiphase nanostructures and nanoscale systems. While conventional vibrational spectroscopies are indispensable physicochemical characterization tools, standard techniques such as Fourier‐transform and quantum cascade laser infrared (IR) microspectroscopies are intrinsically limited in spatial resolution by the wavelength‐dependent diffraction limit of IR light ( ≈ 5–12 µ m). Optical‐photothermal infrared (O‐PTIR) with simultaneous hyperspectral Raman microspectroscopy (O‐PTIR + R) is a novel all‐optical technique that circumvents such diffraction limits, yielding position‐specific IR spectra with sub‐micrometer wavelength‐independent resolution across the mid‐IR. This work implements single‐frequency O‐PTIR with concomitant hyperspectral Raman microspectroscopy to resolve interfacial regions in a poly(octadecyl acrylate)‐ grafted ‐multiwall carbon nanotube (PODA‐ g ‐MWCNT) nanocomposite for wearable temperature sensors and highlights how the O‐PTIR + R technique can be used for analytical characterization and visualization of other nanocomposite systems below resolution limitations of conventional IR spectroscopies.