Nanoscale chemical characterization of a post-consumer recycled polyolefin blend using tapping mode AFM-IR

Abstract

The routine analysis of polymer blends at the nanoscale is usually carried out using electron microscopy techniques such as Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), which often...

Studying the concentration of polymers in blended microplastics using 2D and 3D Raman mapping

“…S3 ). The phase separation of the polymers was also observed to be similar to the PP/PE mixed recyclate 28 . The type of all the samples was confirmed using Raman spectroscopy followed by library matching before any analysis.…”

“…FTIR, however, provides less resolution in comparison to the RS (10–20 µm against 1 µm), thus making this technique less attractive for this purpose 26 , 27 . It was recently shown that the resolution of FTIR can improve the analysis of MPs in the nanoscale regime when it is coupled with Atomic Force Microscopy (AFM) 28 . Nevertheless, this approach significantly increases the complexity and the cost of the analytical instrument, and it only provides 2-D information.…”

Image processing as basis for chemometrics in photothermal atomic force microscopy infrared imaging

“…mixtures of polyethylen, polypropylen and similar materials) with AFM-IR, image ratios of the AFM-IR signal of the CH 2 deformation vibration (around 1460 cm −1 ) and the CH 3 deformation vibration (around 1375 cm −1 ) allow to visualize phase distributions. 6,17 Polyethylene phases should have virtually no presence of CH 3 , whereas polypropylene and similar polyolefins do contain a significant amount of CH 3 . Even such simple ratio images benefit from image registration, as can be seen in fig.…”

AFM-IR for Nanoscale Chemical Characterization in Life Sciences: Recent Developments and Future Directions

“…When measuring spectra this is usually achieved by quickly scanning a set range of frequencies around the original resonance position and adjusting the repetition rate accordingly (chirp) once before each spectrum; however, when recording images a phase-locked loop (PLL) is used instead, which relies on phase angle rather than amplitude to more quickly monitor and react to changes in the peak position. Resonance tracking during AFM-IR imaging is not always able to properly compensate for the shifts observed when measuring samples with large disparities in mechanical properties such as polymer blends, or soft liposomes deposited on a hard substrate. An alternative approach to this problem using a closed-loop piezo controller allowing for off-resonance measurements has also been described .…”

“…However, tapping mode AFM-IR yields lower intensity signals, which may lead to the use of higher laser power that requires care not to damage the sample. An important advantage of tapping mode AFM-IR is the lower sensitivity of the resonance frequency to changes in a sample’s mechanical properties, which can be of relevance, for instance, in polymer samples . This does, however, have its limits, and in extreme cases the use of a PLL to track and adjust the laser frequency (similarly to the resonance-enhanced contact mode) is advisible .…”